PHILOSOPHICAL STUDIES

By

G. E. MOORE, Litt.D.

Hon. LL.D. (St. Andrews), F.B.A.

Lecturer in Moral Science in the University of Cambridge
Author of "Principia Ethica"

LONDON

ROUTLEDGE & KEGAN PAUL LTD

BROADWAY HOUSE: 68-74 CARTER LANE, E.C.4

1922

CONTENTS

Those of the papers in this volume, which have been previously published, originally appeared as follows:—

I. "The Refutation of Idealism" in Mind, N.S. Vol. xii, 1903.

II. "The Nature and Reality of Objects of Perception" in Proceedings of the Aristotelian Society, 1905-6.

III. "Professor James' 'Pragmatism'" in Proceedings of the Aristotelian Society, 1907-8.

IV. "Hume's Philosophy" in The New Quarterly, November, 1909.

V. "The Status of Sense-Data" in Proceedings of the Aristotelian Society, 1913-14.

VI. "The Conception of Reality" in Proceedings of the Aristotelian Society, 1917-18.

VII. "Some Judgments of Perception" in Proceedings of the Aristotelian Society, 1918-19.

IX. "External and Internal Relations" in Proceedings of the Aristotelian Society, 1919-20.

PREFACE

All the papers contained in this volume, except the two ethical ones (VIII and X), have been previously published; and of those which have been previously published all, except that on "External and Internal Relations" (IX), are here re-printed without change. They were written at various dates between 1903 and 1921, and all are here printed in the order in which they were written, except that VIII on "The Conception of Intrinsic Value," which was written earlier than VI and VII, has been moved out of its proper place in order to bring it nearer to IX and X, to both of which it is closely related in subject.

All, except IV and X, were primarily intended for an audience familiar with the writings of philosophers; but I hope that they may nevertheless prove intelligible even to those who have read little or no philosophy, since I make little use of technical terms, and, where I have done so, have done my best to explain in ordinary language exactly what I mean by them. The tone of X is somewhat different from that of the rest, because it was written as a lecture for the Leicester Philosophical Society, with regard to which I was informed that I must not assume any previous acquaintance with philosophy in most of the audience. It accordingly bears marks throughout of the kind of audience for which it was intended.

An attentive reader will easily discover that some of the views expressed in some of the papers are inconsistent with views expressed in others. The fact is that some of the views expressed in some of the earlier ones are views with which I no longer agree; and I feel that some apology is needed for nevertheless republishing them exactly as they stood. In all cases, except one, my excuse is that the mistaken views in question are so embedded in the form and substance of the papers in which they occur, that it would have been impossible to correct them without practically substituting new papers for the old ones; and that, in spite of these mistakes, the old papers, as they stand, still seem to me, on the whole, to say things which are worth saying in a form which, however defective it may be, I doubt my own ability to improve upon. The only case in which I doubt whether this excuse applies is that of the first paper—"The Refutation of Idealism." This paper now appears to me to be very confused, as well as to embody a good many down-right mistakes; so I am doubtful whether I ought to have included it. But in this case I have another excuse: namely that it is a paper to which a good many allusions have been made by contemporary writers on philosophy; and I was told that, for some readers at all events, it would be a convenience that it should be re-printed along with the rest, if only for the sake of reference.

I said above that the only one of the previously published papers, in which changes have been made, is IX on "External and Internal Relations." In this case the changes are not due to any change in my views, but to the fact that, in that part of the paper in which symbols are used, I tried, when it was first published in the Proceedings of the Aristotelian Society, to use the symbols adopted by Whitehead and Russell in Principia Mathematica, and used them also without giving an explanation of their meaning which would be sufficient for readers not acquainted with that work. The symbols in question are symbols which it is difficult for printers to reproduce; and I have, therefore, thought it better, on this occasion, to use another set of symbols, which seem to me to be adequate for the limited purpose I had in view. I have tried to give an explanation of their meaning, which will enable anyone to understand them; and I have taken the opportunity of rewriting some of the parts of the paper in which they occur in a way which will, I hope, make some points clearer than they originally were.

I have to thank the Committee of the Aristotelian Society for permission to reprint the large number of papers (viz., II, III, V, VI, VII and IX), which originally appeared in the Proceedings of that Society; and the Editor of the New Quarterly for permission to reprint the article on Hume's Philosophy (IV), which appeared in that Journal in November, 1909.

G. E. MOORE.

CAMBRIDGE,
January, 1922.

Philosophical Studies

[THE REFUTATION OF IDEALISM]

Modern Idealism, if it asserts any general conclusion about the universe at all, asserts that it is spiritual. There are two points about this assertion to which I wish to call attention. These points are that, whatever be its exact meaning, it is certainly meant to assert (1) that the universe is very different indeed from what it seems, and (2) that it has quite a large number of properties which it does not seem to have. Chairs and tables and mountains seem to be very different from us; but, when the whole universe is declared to be spiritual, it is certainly meant to assert that they are far more like us than we think. The idealist means to assert that they are in some sense neither lifeless nor unconscious, as they certainly seem to be; and I do not think his language is so grossly deceptive, but that we may assume him to believe that they really are very different indeed from what they seem. And secondly when he declares that they are spiritual, he means to include in that term quite a large number of different properties. When the whole universe is declared to be spiritual, it is meant not only that it is in some sense conscious, but that it has what we recognise in ourselves as the higher forms of consciousness. That it is intelligent; that it is purposeful; that it is not mechanical; all these different things are commonly asserted of it. In general, it may be said, this phrase 'reality is spiritual' excites and expresses the belief that the whole universe possesses all the qualities the possession of which is held to make us so superior to things which seem to be inanimate: at least, if it does not possess exactly those which we possess, it possesses not one only, but several others, which, by the same ethical standard, would be judged equal to or better than our own. When we say it is spiritual we mean to say that it has quite a number of excellent qualities, different from any which we commonly attribute either to stars or planets or to cups and saucers.

Now why I mention these two points is that when engaged in the intricacies of philosophic discussion, we are apt to overlook the vastness of the difference between this idealistic view and the ordinary view of the world, and to overlook the number of different propositions which the idealist must prove. It is, I think, owing to the vastness of this difference and owing to the number of different excellences which Idealists attribute to the universe, that it seems such an interesting and important question whether Idealism be true or not. But, when we begin to argue about it, I think we are apt to forget what a vast number of arguments this interesting question must involve: we are apt to assume, that if one or two points be made on either side, the whole case is won. I say this lest it should be thought that any of the arguments which will be advanced in this paper would be sufficient to disprove, or any refutation of them sufficient to prove, the truly interesting and important proposition that reality is spiritual. For my own part I wish it to be clearly understood that I do not suppose that anything I shall say has the smallest tendency to prove that reality is not spiritual: I do not believe it possible to refute a single one of the many important propositions contained in the assertion that it is so. Reality may be spiritual, for all I know; and I devoutly hope it is. But I take 'Idealism' to be a wide term and to include not only this interesting conclusion but a number of arguments which are supposed to be, if not sufficient, at least necessary, to prove it. Indeed I take it that modern Idealists are chiefly distinguished by certain arguments which they have in common. That reality is spiritual has, I believe, been the tenet of many theologians; and yet, for believing that alone, they should hardly be called Idealists. There are besides, I believe, many persons, not improperly called Idealists, who hold certain characteristic propositions, without venturing to think them quite sufficient to prove so grand a conclusion. It is, therefore, only with Idealistic arguments that I am concerned; and if any Idealist holds that no argument is necessary to prove that reality is spiritual, I shall certainly not have refuted him. I shall, however, attack at least one argument, which, to the best of my belief, is considered necessary to their position by all Idealists. And I wish to point out a certain advantage which this procedure gives me—an advantage which justifies the assertion that, if my arguments are sound, they will have refuted Idealism. If I can refute a single proposition which is a necessary and essential step in all Idealistic arguments, then, no matter how good the rest of these arguments may be, I shall have proved that Idealists have no reason whatever for their conclusion.

Suppose we have a chain of argument which takes the form: Since A is B, and B is C, and C is D, it follows A is D. In such an argument, though 'B is C' and 'C is D' may both be perfectly true, yet if 'A is B' be false, we have no more reason for asserting A is D than if all three were false. It does not, indeed, follow that A is D is false; nor does it follow that no other arguments would prove it to be true. But it does follow that, so far as this argument goes, it is the barest supposition, without the least bit of evidence. I propose to attack a proposition which seems to me to stand in this relation to the conclusion 'Reality is spiritual.' I do not propose to dispute that 'Reality is spiritual;' I do not deny that there may be reasons for thinking that it is: but I do propose to show that one reason upon which, to the best of my judgment, all other arguments ever used by Idealists depend is false. These other arguments may, for all I shall say, be eminently ingenious and true; they are very many and various, and different Idealists use the most different arguments to prove the same most important conclusions. Some of these may be sufficient to prove that B is C and C is D; but if, as I shall try to show, their 'A is B' is false the conclusion A is D remains a pleasant supposition. I do not deny that to suggest pleasant and plausible suppositions may be the proper function of philosophy: but I am assuming that the name Idealism can only be properly applied where there is a certain amount of argument, intended to be cogent.

The subject of this paper is, therefore, quite uninteresting. Even if I prove my point, I shall have proved nothing about the Universe in general. Upon the important question whether Reality is or is not spiritual my argument will not have the remotest bearing. I shall only attempt to arrive at the truth about a matter, which is in itself quite trivial and insignificant, and from which, so far as I can see and certainly so far as I shall say, no conclusions can be drawn about any of the subjects about which we most want to know. The only importance I can claim for the subject I shall investigate is that it seems to me to be a matter upon which not Idealists only, but all philosophers and psychologists also, have been in error, and from their erroneous view of which they have inferred (validly or invalidly) their most striking and interesting conclusions. And that it has even this importance I cannot hope to prove. If it has this importance, it will indeed follow that all the most striking results of philosophy—Sensationalism. Agnosticism and Idealism alike—have, for all that has hitherto been urged in their favour, no more foundation than the supposition that a chimera lives in the moon. It will follow that, unless new reasons never urged hitherto can be found, all the most important philosophic doctrines have as little claim to assent as the most superstitious beliefs of the lowest savages. Upon the question what we have reason to believe in the most interesting matters, I do therefore think that my results will have an important bearing; but I cannot too clearly insist that upon the question whether these beliefs are true they will have none whatever.

The trivial proposition which I propose to dispute is this: that esse is percipi. This is a very ambiguous proposition, but, in some sense or other, it has been very widely held. That it is, in some sense, essential to Idealism, I must for the present merely assume. What I propose to show is that, in all the senses ever given to it, it is false.

But, first of all, it may be useful to point out briefly in what relation I conceive it to stand to Idealistic arguments. That wherever you can truly predicate esse you can truly predicate percipi, in some sense or other, is, I take it, a necessary step In all arguments, properly to be called Idealistic, and, what is more, in all arguments hitherto offered for the Idealistic conclusion. If esse is percipi, this is at once equivalent to saying that whatever is, is experienced; and this, again, is equivalent, in a sense, to saying that whatever is, is something mental. But this is not the sense in which the Idealist conclusion must maintain that Reality is mental. The Idealist conclusion is that esse is percipere; and hence, whether esse be percipi or not, a further and different discussion is needed to show whether or not it is also percipere. And again, even if esse be percipere, we need a vast quantity of further argument to show that what has esse has also those higher mental qualities which are denoted by spiritual. This is why I said that the question I should discuss, namely, whether or not esse is percipi, must be utterly insufficient either to prove or to disprove that reality is spiritual. But, on the other hand, I believe that every argument ever used to show that reality is spiritual has inferred this (validly or invalidly) from 'esse is percipere' as one of its premisses; and that this again has never been pretended to be proved except by use of the premiss that esse is percipi. The type of argument used for the latter purpose is familiar enough. It is said that since whatever is, is experienced, and since some things are which are not experienced by the individual, these must at least form part of some experience. Or again that, since an object necessarily implies a subject, and since the whole world must be an object, we must conceive it to belong to some subject or subjects, in the same sense in which whatever is the object of our experience belongs to us. Or again, that, since thought enters into the essence of all reality, we must conceive behind it, in it, or as its essence, a spirit akin to ours, who think: that 'spirit greets spirit' in its object. Into the validity of these inferences I do not propose to enter: they obviously require a great deal of discussion. I only desire to point out that, however correct they may be, yet if esse is not percipi, they leave us as far from a proof that reality is spiritual, as if they were all false too.

But now: Is esse percipi? There are three very ambiguous terms in this proposition, and I must begin by distinguishing the different things that may be meant by some of them.

And first with regard to percipi. This term need not trouble us long at present. It was, perhaps, originally used to mean 'sensation' only; but I am not going to be so unfair to modern Idealists—the only Idealists to whom the term should now be applied without qualification—as to hold that, if they say esse is percipi, they mean by percipi sensation only. On the contrary I quite agree with them that, if esse be percipi at all, percipi must be understood to include not sensation only, but that other type of mental fact, which is called 'thought '; and, whether esse be percipi or not, I consider it to be the main service of the philosophic school, to which modern Idealists belong, that they have insisted on distinguishing 'sensation' and 'thought' and on emphasising the importance of the latter. Against Sensationalism and Empiricism they have maintained the true view. But the distinction between sensation and thought need not detain us here. For, in whatever respects they differ, they have at least this in common, that they are both forms of consciousness or, to use a term that seems to be more in fashion just now, they are both ways of experiencing. Accordingly, whatever esse is percipi may mean, it does at least assert that whatever is, is experienced. And since what I wish to maintain is, that even this is untrue, the question whether it be experienced by way of sensation or thought or both is for my purpose quite irrelevant. If it be not experienced at all, it cannot be either an object of thought or an object of sense. It is only if being involves 'experience' that the question, whether it involves sensation or thought or both, becomes important. I beg, therefore, that percipi may be understood, in what follows, to refer merely to what is common to sensation and thought. A very recent article states the meaning of esse is percipi with all desirable clearness in so far as percipi is concerned.

'I will undertake to show,' says Mr. Taylor,[1] 'that what makes [any piece of fact] real can be nothing but its presence as an inseparable aspect of a sentient experience.' I am glad to think that Mr. Taylor has been in time to supply me with so definite a statement that this is the ultimate premiss of Idealism. My paper will at least refute Mr. Taylor's Idealism, if it refutes anything at all: for I shall undertake to show that what makes a thing real cannot possibly be its presence as an inseparable aspect of a senient experience.

But Mr. Taylor's statement though clear, I think, with regard to the meaning of percipi is highly ambiguous in other respects. I will leave it for the present to consider the next ambiguity in the statement: Esse is percipi. What does the copula mean? What can be meant by saying that Esse is percipi? There are just three meanings, one or other of which such a statement must have, if it is to be true; and of these there is only one which it can have, if it is to be important. (1) The statement may be meant to assert that the word 'esse' is used to signify nothing either more or less than the word 'percipi': that the two words are precise synonyms: that they are merely different names for one and the same thing: that what is meant by esse is absolutely identical with what is meant by percipi. I think I need not prove that the principle esse is percipi is not thus intended merely to define a word; nor yet that, if it were, it would be an extremely bad definition. But if it does not mean this, only two alternatives remain. The second is (2) that what is meant by esse, though not absolutely identical with what is meant by percipi, yet includes the latter as a part of its meaning. If this were the meaning of 'esse is percipi,' then to say that a thing was real would not be the same thing as to say that it was experienced. That it was real would mean that it was experienced and something else besides: 'being experienced' would be analytically essential to reality, but would not be the whole meaning of the term. From the fact that a thing was real we should be able to infer, by the law of contradiction, that it was experienced; since the latter would be part of what is meant by the former. But, on the other hand, from the fact a thing was experienced we should not be able to infer that it was real; since it would not follow from the fact that it had one of the attributes essential to reality, that it also had the other or others. Now, if we understand esse is percipi in this second sense, we must distinguish three different things which it asserts. First of all, it gives a definition of the word 'reality,' asserting that word stands for a complex whole, of which what is meant by 'percipi' forms a part. And secondly it asserts that 'being experienced' forms a part of a certain whole. Both these propositions may be true, and at all events I do not wish to dispute them. I do not, indeed, think that the word 'reality' is commonly used to include 'percipi': but I do not wish to argue about the meaning of words. And that many things which are experienced are also something else—that to be experienced forms part of certain wholes, is, of course, indisputable. But what I wish to point out is, that neither of these propositions is of any importance, unless we add to them a third. That 'real' is a convenient name for a union of attributes which sometimes occurs, it could not be worth any one's while to assert: no inferences of any importance could be drawn from such an assertion. Our principle could only mean that when a thing happens to have percipi as well as the other qualities included under esse, it has percipi: and we should never be able to infer that it was experienced, except from a proposition which already asserted that it was both experienced and something else. Accordingly, if the assertion that percipi forms part of the whole meant by reality is to have any importance, it must mean that the whole is organic, at least in this sense, that the other constituent or constituents of it cannot occur without percipi, even if percipi can occur without them. Let us call these other constituents x. The proposition that esse includes percipi, and that therefore from esse percipi can be inferred, can only be important if it is meant to assert that percipi can be inferred from x. The only importance of the question whether the whole esse includes the part percipi rests therefore on the question whether the part x is necessarily connected with the part percipi. And this is (3) the third possible meaning of the assertion esse is percipi: and, as we now see, the only important one. Esse is percipi asserts that wherever you have x you also have percipi that whatever has the property x also has the property that it is experienced. And this being so, it will be convenient if, for the future, I may be allowed to use the term 'esse' to denote x alone. I do not wish thereby to beg the question whether what we commonly mean by the word 'real' does or does not include percipi as well as x. I am quite content that my definition of 'esse' to denote x, should be regarded merely as an arbitrary verbal definition. Whether it is so or not, the only question of interest is whether from x percipi can be inferred, and I should prefer to be able to express this in the form: can percipi be inferred from esse? Only let it be understood that when I say esse, that term will not for the future include percipi: it denotes only that x, which Idealists, perhaps rightly, include along with percipi under their term esse. That there is such an x they must admit on pain of making the proposition an absolute tautology; and that from this x percipi can be inferred they must admit, on pain of making it a perfectly barren analytic proposition. Whether x done should or should not be called esse is not worth a dispute: what is worth dispute is whether percipi is necessarily connected with x.

We have therefore discovered the ambiguity of the copula in esse is percipi, so far as to see that this principle asserts two distinct terms to be so related, that whatever has the one, which I call esse, has also the property that it is experienced. It asserts a necessary connexion between esse on the one hand and percipi on the other; these two words denoting each a distinct term, and esse denoting a term in which that denoted by percipi is not included. We have, then in esse is percipi, a necessary synthetic proposition which I have undertaken to refute. And I may say at once that, understood as such, it cannot be refuted. If the Idealist chooses to assert that it is merely a self-evident truth, I have only to say that it does not appear to me to be so. But I believe that no Idealist ever has maintained it to be so. Although this—that two distinct terms are necessarily related—is the only sense which 'esse is percipi' can have if it is to be true and important, it can have another sense, if it is to be an important falsehood. I believe that Idealists all hold this important falsehood. They do not perceive that Esse is percipi must, if true, be merely a self-evident synthetic truth: they either identify with it or give as a reason for it another proposition which must be false because it is self-contradictory. Unless they did so, they would have to admit that it was a perfectly unfounded assumption; and if they recognised that it was unfounded, I do not think they would maintain its truth to be evident. Esse is percipi, in the sense I have found for it, may indeed be true; I cannot, refute it: but if this sense were clearly apprehended, no one, I think, would believe that it was true.

Idealists, we have seen, must assert that whatever is experienced, is necessarily so. And this doctrine they commonly express by saying that 'the object of experience is inconceivable apart from the subject.' I have hitherto been concerned with pointing out what meaning this assertion must have, if it is to be an important truth. I now propose to show that it may have an important meaning, which must be false, because it is self-contradictory.

It is a well-known fact in the history of philosophy that necessary truths in general, but especially those of which it is said that the opposite is inconceivable, have been commonly supposed to be analytic, in the sense that the proposition denying them was self-contradictory. It was in this way, commonly supposed, before Kant, that many truths could be proved by the law of contradiction alone. This is, therefore, a mistake which it is plainly easy for the best philosophers to make. Even since Kant many have continued to assert it; but I am aware that among those Idealists, who most properly deserve the name, it has become more fashionable to assert that truths are both analytic and synthetic. Now with many of their reasons for asserting this I am not concerned: it is possible that in some connexions the assertion may bear a useful and true sense. But if we understand 'analytic' in the sense just defined, namely, what is proved by the law of contradiction alone, it is plain that, if 'synthetic' means what is not proved by this alone, no truth can be both analytic and synthetic. Now it seems to me that those who do maintain truths to be both, do nevertheless maintain that they are so in this as well as in other senses. It is, indeed, extremely unlikely that so essential a part of the historical meaning of 'analytic' and 'synthetic' should have been entirely discarded, especially since we find no express recognition that it is discarded. In that case it is fair to suppose that modern Idealists have been influenced by the view that certain truths can be proved by the law of contradiction alone. I admit they also expressly declare that they can not: but this is by no means sufficient to prove that they do not also think they are; since it is very easy to hold two mutually contradictory opinions. What I suggest then is that Idealists hold the particular doctrine in question, concerning the relation of subject and object in experience, because they think it is an analytic truth in this restricted sense that it is proved by the law of contradiction alone.

I am suggesting that the Idealist maintains that object and subject are necessarily connected, mainly because he fails to see that they are distinct, that they are two, at all. When he thinks of 'yellow' and when he thinks of the 'sensation of yellow,' he fails to see that there is anything whatever in the latter which is not in the former. This being so, to deny that yellow can ever be apart from the sensation of yellow is merely to deny that yellow can ever be other than it is; since yellow and the sensation of yellow are absolutely identical. To assert that yellow is necessarily an object of experience is to assert that yellow is necessarily yellow—a purely identical proposition, and therefore proved by the law of contradiction alone. Of course, the proposition also implies that experience is, after all, something distinct from yellow—else there would be no reason for insisting that yellow is a sensation: and that the argument thus both affirms and denies that yellow and sensation of yellow are distinct, is what sufficiently refutes it. But this contradiction can easily be overlooked, because though we are convinced, in other connexions, that 'experience' does mean something and something most important, yet we are never distinctly aware what it means, and thus in every particular case we do not notice its presence. The facts present themselves as a kind of antinomy:

(1) Experience is something unique and different from anything else; (2) Experience of green is entirely indistinguishable from green; two propositions which cannot both be true. Idealists, holding both, can only take refuge in arguing from the one in some connexions and from the other in others.

But I am well aware that there are many Idealists who would repel it as an utterly unfounded charge that they fail to distinguish between a sensation or idea and what I will call its object. And there are, I admit, many who not only imply, as we all do, that green is distinct from the sensation of green, but expressly insist upon the distinction as an important part of their system. They would perhaps only assert that the two form an inseparable unity. But I wish to point out that many, who use this phrase, and who do admit the distinction, are not thereby absolved from the charge that they deny it. For there is a certain doctrine, very prevalent among philosophers nowadays, which by a very simple reduction may be seen to assert that two distinct things both are and are not distinct. A distinction is asserted; but it is also asserted that the things distinguished form an 'organic unity,' But, forming such a unity, it is held, each would not be what it is apart from its relation to the other. Hence to consider either by itself is to make an illegitimate abstraction. The recognition that there are 'organic unities' and 'illegitimate abstractions' in this sense is regarded as one of the chief conquests of modern philosophy. But what is the sense attached to these terms? An abstraction is illegitimate, when and only when we attempt to assert of a part—of something abstracted—that which is true only of the whole to which it belongs: and it may perhaps be useful to point out that this should not be done. But the application actually made of this principle, and what perhaps would be expressly acknowledged as its meaning, is something much the reverse of useful. The principle is used to assert that certain abstractions are in all cases illegitimate; that whenever you try to assert anything whatever of that which is part of an organic whole, what you assert can only be true of the whole. And this principle, so far from being a useful truth, is necessarily false. For if the whole can, nay must, be substituted for the part in all propositions and for all purposes, this can only be because the whole is absolutely identical with the part. When, therefore, we are told that green and the sensation of green are certainly distinct but yet are not separable, or that it is an illegitimate abstraction to consider the one apart from the other, what these provisos are used to assert is, that though the two things are distinct yet you not only can but must treat them as if they were not. Many philosophers, therefore, when they admit a distinction, yet (following the lead of Hegel) boldly assert their right, in a slightly more obscure form of words, also to deny it. The principle of organic unities, like that of combined analysis and synthesis, is mainly used to defend the practice of holding both of two contradictory propositions, wherever this may seem convenient. In this, as in other matters, Hegel's main service to philosophy has consisted in giving a name to and erecting into a principle, a type of fallacy to which experience had shown philosophers, along with the rest of mankind, to be addicted. No wonder that he has followers and admirers.

I have shown then, so far, that when the Idealist asserts the important principle 'Esse is percipi' he must, if it is to be true, mean by this that: Whatever is experienced also must be experienced. And I have also shown that he may identify with, or give as a reason for, this proposition, one which must be false, because it is self contradictory. But at this point I propose to make a complete break in my argument. 'Esse is percipi,' we have seen, asserts of two terms, as distinct from one another as 'green' and 'sweet,' that whatever has the one has also the other: it asserts that 'being' and 'being experienced' are necessarily connected: that whatever is is also experienced. And this, I admit, cannot be directly refuted. But I believe it to be false; and I have asserted that anybody who saw that 'esse and percipi' were as distinct as 'green' and 'sweet' would be no more ready to believe that whatever is is also experienced, than to believe that whatever is green is also sweet. I have asserted that no one would believe that 'esse is percipi' if they saw how different esse is from percipi: but this I shall not try to prove. I have asserted that all who do believe that 'esse is percipi' identify with it or take as a reason for it a self-contradictory proposition: but this I shall not try to prove. I shall only try to show that certain propositions which I assert to be believed, are false. That they are believed, and that without this belief 'esse is percipi' would not be believed either, I must leave without a proof.

I pass, then, from the uninteresting question 'Is 'esse percipi?' to the still more uninteresting and apparently irrelevant question 'What is a sensation or idea?'

We all know that the sensation of blue differs from that of green. But it is plain that if both are sensations they also have some point in common. What is it that they have in common? And how is this common element related to the points in which they differ?

I will call the common element 'consciousness' without yet attempting to say what the thing I so call is. We have then in every sensation two distinct terms, (1) 'consciousness,' in respect of which all sensations are alike; and (2) something else, in respect of which one sensation differs from another. It will be convenient if I may be allowed to call this second term the 'object' of a sensation: this also without yet attempting to say what I mean by the word.

We have then in every sensation two distinct elements, one which I call consciousness, and another which I call the object of consciousness. This must be so if the sensation of blue and the sensation of green, though different in one respect, are alike in another: blue is one object of sensation and green is another, and consciousness, which both sensations have in common, is different from either.

But, further, sometimes the sensation of blue exists in my mind and sometimes it does not; and knowing, as we now do, that the sensation of blue includes two different elements, namely consciousness and blue, the question arises whether, when the sensation of blue exists, it is the consciousness which exists, or the blue which exists, or both. And one point at least is plain: namely that these three alternatives are all different from one another. So that, if any one tells us that to say 'Blue exists' is the same thing as to say that 'Both blue and consciousness exist,' he makes a mistake and a self-contradictory mistake.

But another point is also plain, namely, that when the sensation exists, the consciousness, at least, certainly does exist; for when I say that the sensations of blue and of green both exist, I certainly mean that what is common to both and in virtue of which both are called sensations, exists in each case. The only alternative left, then, is that either both exist or the consciousness exists alone. If, therefore, any one tells us that the existence of blue is the same thing as the existence of the sensation of blue he makes a mistake and a self-contradictory mistake, for he asserts either that blue is the same thing as blue together with consciousness, or that it is the same thing as consciousness alone.

Accordingly to identify either "blue" or any other of what I have called "objects" of sensation, with the corresponding sensation is in every case, a self-contradictory error. It is to identify a part either with the whole of which it is a part or else with the other part of the same whole. If we are told that the assertion "Blue exists" is meaningless unless we mean by it that "The sensation of blue exists," we are told what is certainly false and self-contradictory. If we are told that the existence of blue is inconceivable apart from the existence of the sensation, the speaker probably means to convey to us, by this ambiguous expression, what is a self-contradictory error. For we can and must conceive the existence of blue as something quite distinct from the existence of the sensation. We can and must conceive that blue might exist and yet the sensation of blue not exist. For my own part I not only conceive this, but conceive it to be true. Either therefore this terrific assertion of inconceivability means what is false and self-contradictory or else it means only that as a matter of fact blue never can exist unless the sensation of it exists also.

And at this point I need not conceal my opinion that no philosopher has ever yet succeeded in avoiding this self-contradictory error: that the most striking results both of Idealism and of Agnosticism are only obtained by identifying blue with the sensation of blue: that esse is held to be percipi, solely because what is experienced is held to be identical with the experience of it. That Berkeley and Mill committed this error will, perhaps, be granted: that modern Idealists make it will, I hope, appear more probable later. But that my opinion is plausible, I will now offer two pieces of evidence. The first is that language offers us no means of referring to such objects as "blue" and "green" and "sweet," except by calling them sensations: it is an obvious violation of language to call them "things" or "objects" or "terms." And similarly we have no natural means of referring to such objects as "causality" or "likeness" or "identity," except by calling them "ideas" or "notions" or "conceptions." But it is hardly likely that if philosophers had clearly distinguished in the past between a sensation or idea and what I have called its object, there should have been no separate name for the latter. They have always used the same name for these two different "things" (if I may call them so): and hence there is some probability that they have supposed these "things" not to be two and different, but one and the same. And, secondly, there is a very good reason why they should have supposed so, in the fact that when we refer to introspection and try to discover what the sensation of blue is, it is very easy to suppose that we have before us only a single term. The term "blue" is easy enough to distinguish, but the other element which I have called "consciousness"—that which sensation of blue has in common with sensation of green—is extremely difficult to fix. That many people fail to distinguish it at all is sufficiently shown by the fact that there are materialists. And, in general, that which makes the sensation of blue a mental fact seems to escape us: it seems, if I may use a metaphor, to be transparent—we look through it and see nothing but the blue; we may be convinced that there is something but what it is no philosopher, I think, has yet clearly recognised.

But this was a digression. The point I had established so far was that in every sensation or idea we must distinguish two elements, (1) the "object," or that in which one differs from another; and (2) "consciousness," or that which all have in common—that which makes them sensations or mental facts. This being so, it followed that when a sensation or idea exists, we have to choose between the alternatives that either object alone, or consciousness alone, or both, exist; and I showed that of these alternatives one, namely that the object only exists, is excluded by the fact that what we mean to assert is certainly the existence of a mental fact. There remains the question: Do both exist? Or does the consciousness alone? And to this question one answer has hitherto been given universally: That both exist.

This answer follows from the analysis hitherto accepted of the relation of what I have called "object" to "consciousness" in any sensation or idea. It is held that what I call the object is merely the "content" of a sensation or idea. It is held that in each case we can distinguish two elements and two only, (1) the fact that there is feeling or experience, and (2) what is felt or experienced; the sensation or idea, it is said, forms a whole, in which we must distinguish two "inseparable aspects," "content" and "existence." I shall try to show that this analysis is false; and for that purpose I must ask what may seem an extraordinary question: namely what is meant by saying that one thing is "content" of another? It is not usual to ask this question; the term is used as if everybody must understand it. But since I am going to maintain that "blue" is not the content of the sensation of blue, and what is more important, that, even if it were this analysis would leave out the most important element in the sensation of blue, it is necessary that I should try to explain precisely what it is that I shall deny.

What then is meant by saying that one thing is the "content" of another? First of all I wish to point out that "blue" is rightly and properly said to be part of the content of a blue flower. If, therefore, we also assert that it is part of the content of the sensation of blue, we assert that it has to the other parts (if any) of this whole the same relation which it has to the other parts of a blue flower—and we assert only this: we cannot mean to assert that it has to the sensation of blue any relation which it does not have to the blue flower. And we have seen that the sensation of blue contains at least one other element beside blue—namely, what I call "consciousness," which makes it a sensation. So far then as we assert that blue is the content of the sensation, we assert that it has to this "consciousness" the same relation which it has to the other parts of a blue flower: we do assert this, and we assert no more than this. Into the question what exactly the relation is between blue and a blue flower in virtue of which we call the former part of its "content" I do not propose to enter. It is sufficient for my purpose to point out that it is the general relation most commonly meant when we talk of a thing and its qualities; and that this relation is such that to say the thing exists implies that the qualities also exist. The content of the thing is what we assert to exist, when we assert that the thing exists.

When, therefore, blue is said to be part of the content of the "sensation of blue," the latter is treated as if it were a whole constituted in exactly the same way as any other "thing." The "sensation of blue," on this view, differs from a blue bead or a blue beard, in exactly the same way in which the two latter differ from one another: the blue bead differs from the blue beard, in that while the former contains glass, the latter contains hair; and the "sensation of blue" differs from both in that, instead of glass or hair, it contains consciousness. The relation of the blue to the consciousness is conceived to be exactly the same as that of the blue to the glass or hair: it is in all three cases the quality of a thing.

But I said just now that the sensation of blue was analysed into "content" and "existence," and that blue was said to be the content of the idea of blue. There is an ambiguity in this and a possible error, which I must note in passing. The term "content" may be used in two senses. If we use "content" as equivalent to what Mr. Bradley calls the "what"—if we mean by it the whole of what is said to exist, when the thing is said to exist, then blue is certainly not the content of the sensation of blue: part of the content of the sensation is, in this sense of the term, that other element which I have called consciousness. The analysis of this sensation into the "content" "blue," on the one hand, and mere existence on the other, is therefore certainly false; in it we have again the self-contradictory identification of "Blue exists" with "The sensation of blue exists," But there is another sense in which "blue" might properly be said to be the content of the sensation—namely, the sense in which "content," like εἴδος is opposed to "substance" or "matter." For the element "consciousness," being common to all sensations, may be and certainly is regarded as in some sense their "substance," and by the "content" of each is only meant that in respect of which one differs from another. In this sense then "blue" might be said to be the content of the sensation; but, in that case, the analysis into "content" and "existence" is, at least, misleading, since under "existence" must be included "what exists" in the sensation other than blue.

We have it, then, as a universally received opinion that blue is related to the sensation or idea of blue, as its content, and that this view, if it is to be true, must mean that blue is part of what is said to exist when we say that the sensation exists. To say that the sensation exists is to say both that blue exists and that "consciousness," whether we call it the substance of which blue is the content or call it another part of the content, exists too. Any sensation or idea is a "thing," and what I have called its object is the quality of this thing. Such a "thing" is what we think of when we think of a mental image. A mental image is conceived as if it were related to that of which it is the image (if there be any such thing) in exactly the same way as the image in a looking-glass is related to that of which it is the reflection; in both cases there is identity of content, and the image in the looking-glass differs from that in the mind solely in respect of the fact that in the one case the other constituent of the image is "glass" and in the other case it is consciousness. If the image is of blue, it is not conceived that this "content" has any relation to the consciousness but what it has to the glass: it Is conceived merely to be its content. And owing to the fact that sensations and ideas are all considered to be wholes of this description—things in the mind—the question: What do we know? is considered to be identical with the question: What reason have we for supposing that there are things outside the mind corresponding to these that are inside it?

What I wish to point out is (1) that we have no reason for supposing that there are such things as mental images at all—for supposing that blue is part of the content of the sensation of blue, and (2) that even if there are mental images, no mental image and no sensation or idea is merely a thing of this kind: that 'blue,' even if it is part of the content of the image or sensation or idea of blue, is always also related to it in quite another way, and that this other relation, omitted in the traditional analysis, is the only one which makes the sensation of blue a mental fact at all.

The true analysis of a sensation or idea is as follows. The element that is common to them all, and which I have called "consciousness," really is consciousness. A sensation is, in reality, a case of 'knowing' or 'being aware of' or 'experiencing' something. When we know that the sensation of blue exists, the fact we know is that there exists an awareness of blue. And this awareness is not merely, as we have hitherto seen it must be, itself something distinct and unique, utterly different from blue: it also has a perfectly distinct and unique relation to blue, a relation which is not that of thing or substance to content, nor of one part of content to another part of content. This relation is just that which we mean in every case by 'knowing.' To have in your mind 'knowledge' of blue, is not to have in your mind a 'thing' or 'image' of which blue is the content. To be aware of the sensation of blue is not to be aware of a mental image—of a "thing," of which 'blue' and some other element are constituent parts in the same sense in which blue and glass are constituents of a blue bead. It is to be aware of an awareness of blue; awareness being used, in both cases, in exactly the same sense. This element, we have seen, is certainly neglected by the 'content' theory: that theory entirely fails to express the fact that there is, in the sensation of blue, this unique relation between blue and the other constituent. And what I contend is that this omission is not mere negligence of expression, but is due to the fact that though philosophers have recognised that something distinct is meant by consciousness, they have never yet had a clear conception of what that something is. They have not been able to hold it and blue before their minds and to compare them, in the same way in which they can compare blue and green. And this for the reason I gave above: namely that the moment we try to fix our attention upon consciousness and to see what, distinctly, it is, it seems to vanish: it seems as if we had before us a mere emptiness. When we try to introspect the sensation of blue, all we can see is the blue: the other element is as if it were diaphanous. Yet it can be distinguished if we look attentively enough, and if we know that there is something to look for. My main object in this paragraph has been to try to make the reader see it; but I fear I shall have succeeded very ill.

It being the case, then, that the sensation of blue includes in its analysis, beside blue, both a unique element 'awareness' and a unique relation of this element to blue, I can make plain what I meant by asserting, as two distinct propositions, (1) that blue is probably not part of the content of the sensation at all, and (2) that, even it were, the sensation would nevertheless not be the sensation of blue, if blue had only this relation to it. The first hypothesis may now be expressed by saying that, if it were true, then, when the sensation of blue exists, there exists a blue awareness: offence may be taken at the expression, but yet it expresses just what should be and is meant by saying that blue is, in this case, a content of consciousness or experience. Whether or not, when I have the sensation of blue, my consciousness or awareness is thus blue, my introspection does not enable me to decide with certainty: I only see no reason for thinking that it is. But whether it is or not, the point is unimportant, for introspection does enable me to decide that something else is also true: namely that I am aware of blue, and by this I mean, that my awareness has to blue a quite different and distinct relation. It is possible, I admit, that my awareness is blue as well as being of blue: but what I am quite sure of is that it is of blue; that it has to blue the simple and unique relation the existence of which alone justifies us in distinguishing knowledge of a thing from the thing known, indeed in distinguishing mind from matter. And this result I may express by saying that what is called the content of a sensation is in very truth what I originally called it—the sensation's object.

But, if all this be true, what follows?

Idealists admit that some things really exist of which they are not aware: there are some things, they hold, which are not inseparable aspects of their experience, even if they be inseparable aspects of some experience. They further hold that some of the things of which they are sometimes aware do really exist, even when they are not aware of them: they hold for instance that they are sometimes aware of other minds, which continue to exist even when they are not aware of them. They are, therefore, sometimes aware of something which is not an inseparable aspect of their own experience. They do know some things which are not a mere part or content of their experience. And what my analysis of sensation has been designed to show is, that whenever I have a mere sensation or idea, the fact is that I am then aware of something which is equally and in the same sense not an inseparable aspect of my experience. The awareness which I have maintained to be included in sensation is the very same unique fact which constitutes every kind of knowledge: "blue" is as much an object, and as little a mere content, of my experience, when I experience it, as the most exalted and independent real thing of which I am ever aware. There is, therefore, no question of how we are to "get outside the circle of our own ideas and sensations." Merely to have a sensation is already to be outside that circle. It is to know something which is as truly and really not a part of my experience, as anything which I can ever know.

Now I think I am not mistaken in asserting that the reason why Idealists suppose that everything which is must be an inseparable aspect of some experience, is that they suppose some things, at least, to be inseparable aspects of their experience. And there is certainly nothing which they are so firmly convinced to be an inseparable aspect of their experience as what they call the content of their ideas and sensations. If, therefore, this turns out in every case, whether it be also the content or not, to be at least not an inseparable aspect of the experience of it, it will be readily admitted that nothing else which we experience ever is such an inseparable aspect. But if we never experience anything but what is not an inseparable aspect of that experience, how can we infer that anything whatever, let alone everything, is an inseparable aspect of any experience? How utterly unfounded is the assumption that "esse is percipi" appears in the clearest light.

But further I think it may be seen that if the object of an Idealist's sensation were, as he supposes, not the object but merely the content of that sensation, if, that is to say, it really were an inseparable aspect of his experience, each Idealist could never be aware either of himself or of any other real thing. For the relation of a sensation to its object is certainly the same as that of any other instance of experience to its object; and this, I think, is generally admitted even by Idealists: they state as readily that what is judged or thought or perceived is the content of that judgment or thought or perception, as that blue Is the content of the sensation of blue. But, if so, then when any Idealist thinks he is aware of himself or of any one else, this cannot really be the case. The fact Is, on his own theory, that himself and that other person are in reality mere contents of an awareness, which is aware of nothing whatever. All that can be said is that there is an awareness in him, with a certain content: it can never be true that there is in him a consciousness of anything. And similarly he is never aware either of the fact that he exists or that reality is spiritual. The real fact, which he describes in those terms, is that his existence and the spirituality of reality are contents of an awareness, which is aware of nothing—certainly not, then, of it own content.

And further if everything, of which he thinks he is aware, is in reality merely a content of his own experience he has certainly no reason for holding that anything does exist except himself: it will, of course, be possible that other persons do exist; solipsism will not be necessarily true; but he cannot possibly infer from anything he holds that it is not true. That he himself exists will of course follow from his premiss that many things are contents of his experience. But since everything, of which he thinks himself aware, is in reality merely an inseparable aspect of that awareness; this premiss allows no inference that any of these contents, far less any other consciousness, exists at all except as an inseparable aspect of his awareness, that is, as part of himself.

Such, and not those which he takes to follow from it, are the consequences which do follow from the Idealist's supposition that the object of an experience is in reality merely a content or inseparable aspect of that experience. If, on the other hand, we clearly recognise the nature of that peculiar relation which I have called "awareness of anything"; if we see that this is involved equally in the analysis of every experience—from the merest sensation to the most developed perception or reflexion, and that this is in fact the only essential element in an experience—the only thing that is both common and peculiar to all experiences—the only thing which gives us reason to call any fact mental; if, further, we recognise that this awareness is and must be in all cases of such a nature that its object, when we are aware of it, is precisely what it would be, if we were not aware: then it becomes plain that the existence of a table in space is related to my experience of it in precisely the same way as the existence of my own experience is related to my experience of that. Of both we are merely aware: if we are aware that the one exists, we are aware in precisely the same sense that the other exists; and if it is true that my experience can exist, even when I do not happen to be aware of its existence, we have exactly the same reason for supposing that the table can do so also. When, therefore, Berkeley, supposed that the only thing of which I am directly aware is my own sensations and ideas, he supposed what was false; and when Kant supposed that the objectivity of things in space consisted in the fact that they were "Vorstellungen" having to one another different relations from those which the same "Vorstellungen" have to one another in subjective experience, he supposed what was equally false. I am as directly aware of the existence of material things in space as of my own sensations; and what I am aware of with regard to each is exactly the same—namely that in one case the material thing, and in the other case my sensation does really exist. The question requiring to be asked about material things is thus not: What reason have we for supposing that anything exists corresponding to our sensations? but: What reason have we for supposing that material things do not exist, since their existence has precisely the same evidence as that of our sensations? That either exist may be false; but if it is a reason for doubting the existence of matter, that it is an inseparable aspect of our experience, the same reasoning will prove conclusively that our experience does not exist either, since that must also be an inseparable aspect of our experience of it. The only reasonable alternative to the admission that matter exists as well as spirit, is absolute Scepticism—that, as likely as not nothing exists at all. All other suppositions—the Agnostic's, that something, at all events, does exist, as much as the Idealist's, that spirit does—are, if we have no reason for believing in matter, as baseless as the grossest superstitions.

[1] International Journal of Ethics, October, 1902.

[THE NATURE AND REALITY OF OBJECTS OF PERCEPTION]

There are two beliefs in which almost all philosophers, and almost all ordinary people are agreed. Almost everyone believes that he himself and what he directly perceives do not constitute the whole of reality: he believes that something other than himself and what he directly perceives exists or is real. I do not mean to say that almost everyone believes that what he directly perceives is real: I only mean that he does believe that, whether what he directly perceives is real or not, something other than it and other than himself certainly is so. And not only does each of us thus agree in believing that something other than himself and what he directly perceives is real: almost everyone also believes that among the real things, other than himself and what he directly perceives, are other persons who have thoughts and perceptions in some respects similar to his own. That most people believe this I think I need scarcely try to show. But since a good many philosophers may appear to have held views contradictory of this one, I will briefly point out my reason for asserting that most philosophers, even among those (if any) who have believed the contradictory of this, have yet held this as well. Almost all philosophers tell us something about the nature of human knowledge and human perception. They tell us that we perceive so and so; that the nature or origin of our perceptions is such and such; or (as I have just been telling you) that men in general have such and such beliefs. It might, indeed, be said that we are not to interpret such language too strictly: that, though a philosopher talks about human knowledge and our perceptions, he only means to talk about his own. But in many cases a philosopher will leave no doubt upon this point, by expressly assuming that there are other perceptions, which differ in some respects from his own: such, for instance, is the case when (as is so common nowadays) a philosopher introduces psycho-genetic considerations into his arguments —considerations concerning the nature of the perceptions of men who existed before and at a much lower stage of culture than himself. Any philosopher, who uses such arguments, obviously assumes that perceptions other than his own have existed or been real. And even those philosophers who think themselves justified in the conclusion that neither their own perceptions nor any perceptions like theirs are ultimately real, would, I think admit, that phenomenally, at least, they are real, and are certainly more real than some other things.

Almost everyone, then, does believe that some perceptions other than his own, and which he himself does not directly perceive, are real; and believing this, he believes that something other than himself and what he directly perceives is real. But how do we know that anything exists except our own perceptions, and what we directly perceive? How do we know that there are any other people, who have perceptions in some respects similar to our own?

I believe that these two questions express very exactly the nature of the problem which it is my chief object, in this paper, to discuss. When I say these words to you, they will at once suggest to your minds the very question, to which I desire to find an answer; they will convey to you the very same meaning which I have before my mind, when I use the words. You will understand at once what question it is that I mean to ask. But, for all that, the words which I have used are highly ambiguous. If you begin to ask yourselves what I do mean by them, you will find that there are several quite different things which I might mean. And there is, I think, great danger of confusing these different meanings with one another. I think that philosophers, when they have asked this question in one sense, have often answered it in quite a different sense; and yet have supposed that the answer which they have given is an answer to the very same question which they originally asked. It is precisely because there is this ambiguity—this danger of confusion, in the words which I have used, that I have chosen to use them. I wish to point out as clearly as I can, not only what I do mean by them, but also some things which I do not mean; and I wish to make it clear that the questions which I do not mean to ask, are different questions from that which I do mean to ask.

I will take the second of my two questions, since there is in the other an additional ambiguity to which I do not now wish to call attention. My second question was: How do we know that there exist any other people who have perceptions in some respects similar to our own? What does this question mean?

Now I think you may have noticed that when you make a statement to another person, and he answers "How do you know that that is so?" he very often means to suggest that you do not know it. And yet, though he means to suggest that you do not know it, he may not for a moment wish to suggest that you do not believe it, nor even that you have not that degree or kind of conviction, which goes beyond mere belief, and which may be taken to be essential to anything which can properly be called knowledge. He does not mean to suggest for a moment that you are saying something which you do not believe to be true, or even that you are not thoroughly convinced of its truth. What he does mean to suggest is that what you asserted was not true, even though you may not only have believed it but felt sure that it was true. He suggests that you don't know it, in the sense that what you believe or feel sure of is not true.

Now I point this out, not because I myself mean to suggest that we don't know the existence of other persons, but merely in order to show that the word "know" is sometimes used in a sense in which it is not merely equivalent to "believe" or "feel sure of." When the question "How do you know that?" is asked, the questioner does not merely mean to ask "how do you come to believe that, or to be convinced of it?" He sometimes, and I think generally, means to ask a question with regard to the truth, and not with regard to the existence of your belief. And similarly when I ask the question "How do we know that other people exist?" I do not mean to ask "How do we come to believe in or be convinced of their existence?" I do not intend to discuss this question at all. I shall not ask what suggests to us our belief in the existence of other persons or of an external world; I shall not ask whether we arrive at it by inference or by "instinct" or in any other manner, which ever has been or may be suggested: I shall discuss no question of any kind whatever with regard to its origin, or cause, or the way in which it arises. These psychological questions are not what I propose to discuss. When I ask the question "How do we know that other people exist?" I do not mean:

"How does our belief in their existence arise?"

But if I do not mean this what do I mean P I have said that I mean to ask a question with regard to the truth of that belief; and the particular question which I mean to ask might be expressed in the words: What reason have we for our belief in the existence of other persons? But these are words which themselves need some explanation, and I will try to give it.

In the first place, then, when I talk of "a reason," I mean only a good reason and not a bad one. A bad reason is, no doubt, a reason, in one sense of the word; but I mean to use the word "reason" exclusively in the sense in which it is equivalent to "good reason." But what, then, is meant by a good reason for a belief? I think I can express sufficiently accurately what I mean by it in this connection, as follows:—A good reason for a belief is a proposition which is true, and which would not be true unless the belief were also true. We should, I think, commonly say that when a man knows such a proposition, he has a good reason for his belief; and, when he knows no such proposition, we should say that he has no reason for it. When he knows such a proposition, we should say he knows something which is a reason for thinking his belief to be true—something from which it could be validly inferred. And if, in answer to the question "How do you know so and so?" he were to state such a proposition, we should, I think, feel that he had answered the question which we meant to ask. Suppose, for instance, in answer to the question "How do you know that?" he were to say "I saw it in the Times." Then, if we believed that he had seen it in the Times, and also believed that it would not have been in the Times, unless it had been true, we should admit that he had answered our question. We should no longer doubt that he did know what he asserted, we should no longer doubt that his belief was true. But if, on the other hand, we believed that he had not seen it in the Times—if, for instance, we had reason to believe that what he saw was not the statement which he made, but some other statement which he mistook for it; or if we believed that the kind of statement in question was one with regard to which there was no presumption that, being in the Times, it would be true: in either of these cases we should, I think, feel that he had not answered our question. We should still doubt whether what he had said was true. We should still doubt whether he knew what he asserted; and since a man cannot tell you how he knows a thing unless he does know that thing, we should think that, though he might have told us truly how he came to believe it, he had certainly not told us how he knew it. But though we should thus hold that he had not told us how he knew what he had asserted, and that he had given us no reason for believing it to be true; we must yet admit that he had given us a reason in a sense—a bad reason, a reason which was no reason because it had no tendency to show that what he believed was true; and we might also be perfectly convinced that he had given us the reason why he believed it—the proposition by believing which he was induced also to believe his original assertion.

I mean, then, by my question, "How do we know that other people exist?" what, I believe, is ordinarily meant, namely, "What reason have we for believing that they exist?" and by this again I mean, what I also believe is ordinarily meant, namely, "What proposition do we believe, which is both true itself and is also such that it would not be true, unless other people existed?" And I hope it is plain that this question, thus explained, is quite a different question from the psychological question, which I said I did not mean to ask—from the question, "How does our belief in the existence of other people arise?" My illustration, I hope, has made this plain. For I have pointed out that we may quite well hold that a man has told us how a belief of his arises, and even what was the reason which made him adopt that belief, and yet may have failed to give us any good reason for his belief—any proposition which is both true itself, and also such that the truth of his belief follows from it. And, indeed, it is plain that if any one ever believes what is false, he is believing something for which there is no good reason, in the sense which I have explained, and for which, therefore, he cannot possibly have a good reason; and yet it plainly does not follow that his belief did not arise in anyway whatever, nor even that he had no reason for it—no bad reason. It is plain that false beliefs do arise in some way or other—they have origins and causes: and many people who hold them have bad reasons for holding them—their belief does arise (by inference or otherwise) from their belief in some other proposition, which is not itself true, or else is not a good reason for holding that, which they infer from it, or which, in some other way, it induces them to believe. I submit, therefore, that the question, "What good reason have we for believing in the existence of other people?" is different from the question, "How does that belief arise?" But when I say this, I must not be misunderstood; I must not be understood to affirm that the answer to both questions may not, in a sense, be the same. I fully admit that the very same fact, which suggests to us the belief in the existence of other people, may also be a good reason for believing that they do exist. All that I maintain is that the question whether it is a good reason for that belief is a different question from the question whether it suggests that belief: if we assert that a certain fact both suggests our belief in the existence of other persons and is also a good reason for holding that belief, we are asserting two different things and not one only. And hence, when I assert, as I shall assert, that we have a good reason for our belief in the existence of other persons, I must not be understood also to assert either that we infer the existence of other persons from this good reason, or that our belief in that good reason suggests our belief in the existence of other persons in any other way. It is plain, I think, that a man may believe two true propositions, of which the one would not be true, unless the other were true too, without, in any sense whatever, having arrived at his belief in the one from his belief in the other; and it is plain, at all events, that the question whether his belief in the one did arise from his belief in the other, is a different question from the question whether the truth of the one belief follows from the truth of the other.

I hope, then, that I have made it a little clearer what I mean by the question: "What reason have we for believing in the existence of other people?" and that what I mean by it is at all events different from what is meant by the question: "How does our belief in the existence of other people arise?"

But I am sorry to say that I have not yet reached the end of my explanations as to what my meaning is. I am afraid that the subject may seem very tedious. I can assure you that I have found it excessively tedious to try to make my meaning clear to myself. I have constantly found that I was confusing one question with another, and that, where I had thought I had a good reason for some assertion, I had in reality no good reason. But I may perhaps remind you that this question, "How do we know so and so?" "What reason have we for believing it?" is one of which philosophy is full; and one to which the most various answers have been given. Philosophy largely consists in giving reasons; and the question what are good reasons for a particular conclusion and what are bad, is one upon which philosophers have disagreed as much as on any other question. For one and the same conclusion different philosophers have given not only different, but incompatible, reasons; and conversely different philosophers have maintained that one and the same fact is a reason for incompatible conclusions. We are apt, I think, sometimes to pay too little attention to this fact. When we have taken, perhaps, no little pains to assure ourselves that our own reasoning is correct, and especially when we know that a great many other philosophers agree with us, we are apt to assume that the arguments of those philosophers, who have come to a contradictory conclusion, are scarcely worthy of serious consideration. And yet, I think, there is scarcely a single reasoned conclusion in philosophy, as to which we shall not find that some other philosopher, who has, so far as we know, bestowed equal pains on his reasoning, and with equal ability, has reached a conclusion incompatible with ours. We may be satisfied that we are right, and we may, in fact, be so; but it is certain that both cannot be right: either our opponent or we must have mistaken bad reasons for good. And this being so, however satisfied we may be that it is not we who have done so, I think we should at least draw the conclusion that it is by no means easy to avoid mistaking bad reasons for good; and that no process, however laborious, which is in the least likely to help us in avoiding this should be evaded. But it is at least possible that one source of error lies in mistaking one kind of reason for another—in supposing that, because there is, in one sense, a reason for a given conclusion, there is also a reason in another, or that because there is, in one sense, no reason for a given conclusion, there is, therefore, no reason at all. I believe myself that this is a very frequent source of error: but it is at least a possible one. And where, as disagreements show, there certainly is error on one side or the other, and reason, too, to suppose that the error is not easy to detect, I think we should spare no pains in investigating any source, from which it is even possible that the error may arise. For these reasons I think I am perhaps doing right in trying to explain as clearly as possible not only what reasons we have for believing in an external world, but also in what sense I take them to be reasons.

I proceed, then with my explanation. And there is one thing, which, I think my illustration has shown that I do not mean. I have defined a reason for a belief as a true proposition, which would not be true unless the belief itself—what is believed—were also true; and I have used, as synonymous with this form of words, the expressions: A reason for a belief is a true proposition from which the truth of the belief follows from which it could be validly inferred. Now these expressions might suggest the idea that I mean to restrict the word "reason," to what, in the strictest sense, might be called a logical reason—to propositions from which the belief in question follows, according to the rules of inference accepted by Formal Logic. But I am not using the words "follow," "validly inferred," in this narrow sense; I do not mean to restrict the words "reason for a belief" to propositions from which the laws of Formal Logic state that the belief could be deduced. The illustration which I gave is inconsistent with this restricted meaning. I said that the fact that a statement appeared in the Times might be a good reason for believing that that statement was true. And I am using the word "reason" in the wide and popular sense, in which it really might be. If, for instance, the Times stated that the King was dead, we should think that was a good reason for believing that the King was dead; we should think that the Times would not have made such a statement as that unless the King really were dead. We should, indeed, not think that the statement in the Times rendered it absolutely certain that the King was dead. But it is extremely unlikely that the Times would make a statement of this kind unless it were true; and, in that sense, the fact of the statement appearing in the Times would render it highly probable—much more likely than not—that the King was dead. And I wish it to be understood that I am using the words "reason for a belief" in this extremely wide sense. When I look for a good reason for our belief in the existence of other people, I shall not reject any proposition merely on the ground that it only renders their existence probable—only shows it to be more likely than not that they exist. Provided that the proposition in question does render it positively probable that they exist, then, if it also conforms to the conditions which I am about to mention, I shall call it a "good reason."

But it is not every proposition which renders it probable that other people exist, which I shall consider to be a good answer to my question. I have just explained that my meaning is wide in one direction—in admitting some propositions which render a belief merely probable; but I have now to explain that it is restricted in two other directions. I do mean to exclude certain propositions which do render that belief probable. When I ask: What reason have we for believing in the existence of other people? a certain ambiguity is introduced by the use of the plural "we." If each of several different persons has a reason for believing that he himself exists, then it is not merely probable, but certain, according to the rules of Formal Logic, that, in a sense, they "have a reason for believing" that several people exist; each has a reason for believing that he himself exists; and, therefore, all of them, taken together, have reasons for supposing that several persons exist. If, therefore, I were asking the question: What reason have we for believing in the existence of other persons? in this sense, it would follow that if each of us has a reason for believing in his own existence, these reasons, taken together, would be a reason for believing in the existence of all of us. But I am not asking the question in this sense: it is plain that this is not its natural sense. What I do mean to ask is: Does each single one of us know any proposition, which is a reason for believing that others exist? I am using "we," that is to say, in the sense of "each of us." But again I do mean each of us: I am not merely asking whether some one man knows a proposition which is a reason for believing that other men exist. It would be possible that some one man, or some few men, should know such a proposition, and yet the rest know no such proposition. But I am not asking whether this is the case. I am asking whether among propositions of the kind which (as we commonly suppose) all or almost all men know, there is any which is a reason for supposing that other men exist. And in asking this question I am not begging the question by supposing that all men do exist. My question might, I think, be put quite accurately as follows. There are certain kinds of belief which, as we commonly suppose, all or almost all men share. I describe this kind of belief as "our" beliefs, simply as an easy way of pointing out which kind of belief I mean, but without assuming that all men do share them. And I then ask: Supposing a single man to have beliefs of this kind, which among them would be a good reason for supposing that other men existed having like beliefs?

This, then, is the first restriction which I put upon the meaning of my question. And it is, I think, a restriction which, in their natural meaning, the words suggest. When we ask: What reason have we for believing that other people exist? we naturally understand that question to be equivalent to: What reason has each of us for that belief? And this question again is naturally equivalent to the question: Which among the propositions that a single man believes, but which are of the kind which (rightly or wrongly) we assume all men to believe, are such that they would not be true unless some other person than that man existed? But there is another restriction which, I think, the words of my question also naturally suggest. If we were to ask anyone the question: How do you know that you did see that statement in the Times? and he were to answer "Because I did see it in the Times and in the Standard too," we should not think that he had given us a reason for the belief that he saw it in the Times. We should not think his answer a reason, because it asserts the very thing for which we require a reason. And similarly when I ask: How do we know that any thing or person exists, other than ourselves and what we directly perceive? What reason have we for believing this? I must naturally be understood to mean: What proposition, other than one which itself asserts or presupposes the existence of something beyond ourselves and our own perceptions, is a reason for supposing that such a thing exists? And this restriction obviously excludes an immense number of propositions of a kind which all of us do believe. We all of us believe an immense number of different propositions about the existence of things which we do not directly perceive, and many of these propositions are, in my sense, good reasons for believing in the existence of still other things. The belief in the existence of a statement in the Times, when we have not seen that statement, may, as I implied, be a good reason for believing that someone is dead. But no such proposition can be a good answer to my question, because it asserts the very kind of thing for which I require a reason: it asserts the existence of something other than myself and what I directly perceive. When I am asking: What reason have I for believing in the existence of anything but myself, my own perceptions, and what I do directly perceive? you would naturally understand me to mean: What reason, other than the existence of such a thing, have I for this belief?

Each of us, then, we commonly assume, believes some true propositions, which do not themselves assert the existence of anything other than himself, his own perceptions, or what he directly perceives. Each of us, for instance, believes that he himself has and has had certain particular perceptions: and these propositions are propositions of the kind I mean—propositions which do not themselves assert the existence of anything other than himself, his own perceptions, and what he directly perceives: they are, I think, by no means the only propositions of this kind, which most of us believe: but they are propositions of this kind. But, as I say, I am not assuming that each of us—each of several different people—does believe propositions of this kind. All that I assume is that at least one man does believe some such propositions. And then I ask: Which among those true propositions, which one man believes, are such that they would probably not be true, unless some other man existed and had certain particular perceptions? Which among them are such that it follows (in the wide sense, which I have explained) from their truth, that it is more likely than not that some other man has perceptions? This is the meaning of my question, so far as I have hitherto explained it: and I hope this meaning is quite clear. It is in this sense that I am asking: What reason have we for believing that other people exist? How do we know that they exist? This, indeed, is not all that I mean by that question: there is one other point—the most important one—which remains to be explained. But this is part of what I mean to ask; and before I go on to explain what else I mean, I wish first to stop and enquire what is the answer to this part of my question. What is the answer to the question: Which among the true propositions, of a kind which (as we commonly assume) each of us believes, and which do not themselves assert the existence of anything other than that person himself, his own perceptions, or what he directly perceives, are such that they would probably not be true unless some other person existed, who had perceptions in some respects similar to his own?

Now to this question the answer is very obvious. It is very obvious that in this sense we have reasons for believing in the existence of other persons, and also what some of those reasons are. But I wish to make it quite plain that this is so: that in this sense one man has a reason for believing that another has certain perceptions. All that I am asking you to grant, is, you see, that some of you would not be having just those perceptions which you now have, unless I, as I read this paper, were perceiving more or less black marks on a more or less white ground; or that I on the other hand, should not be having just those perceptions which I now have, unless some other persons than myself were hearing the sounds of my voice. And I am not asking you even to grant that this is certain—only that it is positively probable—more likely than not. Surely it is very obvious that this proposition is true. But I wish to make it quite clear what would be the consequences of denying that any such propositions are true—propositions which assert that the existence of certain perceptions in one man are a reason for believing in the existence of certain perceptions in another man—which assert that one man would probably not have had just those perceptions which he did have, unless some other man had had certain particular perceptions. It is plain, I think, that, unless some such propositions are true, we have no more reason for supposing that Alexander the Great ever saw an elephant, than for supposing that Sindbad the Sailor saw a Roc; we have no more reason for supposing that anybody saw Julius Caesar murdered in the Senate House at Rome, than for supposing that somebody saw him carried up to Heaven in a fiery chariot. It is plain, I think, that if we have any reason at all for supposing that in all probability Alexander the Great did see an elephant, and that in all probability no such person as Sindbad the Sailor ever saw a Roc, part of that reason consists in the assumption that some other person would probably not have had just those perceptions which he did have, unless Alexander the Great had seen an elephant, and unless Sindbad the Sailor had not seen a Roc. And most philosophers, I think, are willing to admit that we have some reason, in some sense or other, for such propositions as these. They are willing to admit not only that some persons probably did see Julius Caesar murdered in the Senate House; but also that some persons, other than those who saw it, had and have some reason for supposing that some one else probably saw it. Some sceptical philosophers might, indeed, deny both propositions; and to refute their views, I admit, other arguments are needed than any which I shall bring forward in this paper. But most philosophers will, I think, admit not only that facts, for which there is, as we say, good historical evidence, are probably true; but also that what we call good historical evidence really is in some sense a good reason for thinking them true. Accordingly I am going to assume that many propositions of the following kind are true. Propositions, namely, which assert that one man would probably not have certain perceptions which he does have, unless some other man had certain particular perceptions. That some of you, for instance, would probably not be having precisely the perceptions which you are having, unless I were having the perception of more or less black marks on a more or less white ground. And, in this sense, I say, we certainly have reasons for supposing that other people have perceptions similar, in some respects, to those which we sometimes have.

But when I said I was going to ask the question: What reason have we for supposing that other people exist? you will certainly not have thought that I merely meant to ask the question which I have just answered. My words will have suggested to you something much more important than merely this. When, for instance, I said that to the question "How do you know that?" the answer "I saw it in the Times" would be a satisfactory answer, you may have felt, as I felt, that it would not in all circumstances be regarded as such. The person who asked the question might, in some cases, fairly reply: "That is no answer: how do you know that, because you saw a thing in the Times, it is therefore true?" In other words he might ask fora reason for supposing that the occurrence of a particular statement in the Times was a reason for supposing that statement true. And this is a question to which we all believe that there may be an answer. We believe that, with some kinds of statements which the Times makes—some kinds of statements with regard to Fiscal Policy for example—the fact that the Times makes them is no reason for supposing them to be true: whereas with regard to other kinds of statements, which it makes, such a statement, for instance, as that the King was dead, the fact that it makes them is a reason for supposing them true. We believe that there are some kinds of statements, which it is very unlikely the Times would make, unless they were true; and others which it is not at all unlikely that the Times might make, although they were not true. And we believe that a reason might be given for distinguishing, in this way, between the two different kinds of statement: for thinking that, in some cases (on points, for instance, which, as we should say, are not simple questions of fact) the Times is fallible, whereas in other cases, it is, though not absolutely infallible, very unlikely to state what is not true.

Now it is precisely in this further sense that I wish to consider: what reason have we for believing that certain particular things, other than ourselves, our own perceptions, and what we directly perceive, are real? I have asserted that I do have certain perceptions, which it is very unlikely I should have, unless some other person had certain particular perceptions; that, for instance, it is very unlikely I should be having precisely those perceptions which I am now having unless someone else were hearing the sound of my voice. And I now wish to ask: What reason have I for supposing that this is unlikely? What reason has any of us for supposing that any such proposition is true? And I mean by "having a reason" precisely what I formerly meant. I mean: What other proposition do I know, which would not be true, unless my perception were connected with someone else's perception, in the manner in which I asserted them to be connected? Here again I am asking for a good reason; and am not asking a psychological question with regard to origin. Here again I am not asking for a reason, in the strict sense of Formal Logic; I am merely asking for a proposition which would probably not be true, unless what I asserted were true. Here again I am asking for some proposition of a kind which each of us believes; I am asking: What reason has each of us for believing that some of his perceptions are connected with particular perceptions of other people in the manner I asserted?—for believing that he would not have certain perceptions that he does have, unless some other person had certain particular perceptions? And here again I am asking for a reason—I am asking for some proposition other than one which itself asserts: When one man has a perception of such and such a particular kind, it is probable that another man has a perception or thought of this or that other kind.

But what kind of reason can be given for believing a proposition of this sort? For believing a proposition which asserts that, since one particular thing exists, it is probable that another particular thing also exists? One thing I think is plain, namely that we can have no good reason for believing such a proposition, unless we have good reason for believing some generalisation. It is commonly believed, for instance, that certain so-called flint arrow-heads, which have been discovered, were probably made by prehistoric men; and I think it is plain that we have no reason for believing this unless we have reason to suppose that objects which resemble these in certain particular respects are generally made by men—are more often made by men than by any other agency. Unless certain particular characteristics which those arrow-heads have were characteristics which belonged at least more frequently to articles of human manufacture than to any articles not made by men, it would surely be just as likely as not that these arrowheads were not made by men—that they were, in fact not arrow-heads. That is to say, unless we have reason to assert a generalisation—the generalisation that objects of a certain kind are generally made by men, we have no reason to suppose that these particular objects, which are of the kind in question, were made by men. And the same, so far as I can see, is true universally. If we ever have any reason for asserting that, since one particular thing exists, another probably exists or existed or will exist also part of our reason, at least, must consist in reasons for asserting some generalisation—for asserting that the existence of things of a particular kind is, more often than not, accompanied or preceded or followed by the existence of things of another particular kind. It is, I think, sometimes assumed that an alternative to this theory may be found in the theory that the existence of one kind of thing "intrinsically points to," or is "intrinsically a sign or symbol of" the existence of another thing. It is suggested that when a thing which thus points to the existence of another thing exists, then it is at least probable that the thing "pointed to" exists also. But this theory, I think, offers no real alternative. For, in the first place, when we say that the existence of one thing A is a "sign of" or "points to" the existence of another thing B, we very commonly actually mean to say that when a thing like A exists, a thing like B generally exists too. We may, no doubt, mean something else too; but this we do mean. We say, for instance, that certain particular words, which we hear or read, are a "sign" that somebody has thought of the particular things which we call the meaning of those words. But we should certainly hesitate to admit that the hearing or reading of certain words could be called a "sign" of the existence of certain thoughts, unless it were true that when those words are heard or read, the thoughts in question generally have existed. If when those words were heard or read, the thoughts had generally not existed, we should say that, in one sense of the word at all events, the hearing of the words was not a sign of the existence of the thoughts. In this sense, therefore, to say that the existence of A "points to" or "is a sign of" the existence of B is actually to say that when A exists, B generally exists also. But, no doubt, the words "points to" "is a sign of" may be used in some other sense: they may, for instance, mean only that the existence of A suggests in some way the belief that B exists. And in such a case we certainly might know that the existence of A pointed to the existence of B, without knowing that when A existed B generally existed also. Let us suppose, then, that in some such sense A does "point to" the existence of B; can this fact give us a reason for supposing it even probable that B existed. Certainly it can, provided it is true that when A does point to the existence of B, B generally exists. But surely it can do so, only on this condition. If when A points to the existence of B, B, nevertheless, does not generally exist, then surely the fact that A points to the existence of B can constitute no probability that B does not exist: on the contrary it will then be probable that, even though A "points to" the existence of B, B does not exist. We have, in fact, only substituted the generalisation that A's pointing to B is generally accompanied by the existence of B, for the generalisation that A's existence is generally accompanied by the existence of B. If we are to have any reason for asserting that, when A points to or is a sign of the existence of B, B probably exists, we must still have a reason for some generalisation—for a generalisation which asserts that when one thing points to the existence of another, that other generally exists.

It is plain, then, I think, that if we are to find a reason for the assertion that some particular perception of mine would probably not exist, unless someone else were having or had had a perception of a kind which I can name, we must find a reason for some generalisation. And it is also plain, I think, that in many cases of this kind the generalisation must consist in an assertion that when one man has a certain kind of perception, some other man generally has had some other perception or belief. We assume, for instance, that when we hear or read certain words, somebody besides ourselves has thought the thoughts, which constitute the meaning of those words; and it is plain, I think, that we have no reason for this assumption except one which is also a reason for the assumption that when certain words are heard or read, somebody generally has had certain thoughts. And my enquiry, therefore, at least includes the enquiry: What reasons have we for such generalisations as these? for generalisations which assert a connection between the existence of a certain kind of perception in one man, and that of a certain kind of perception or belief in another man?

And to this question, I think, but one answer can be given. If we have any reason for such generalisations at all, some reason must be given, in one way or another, by observation—by observation, understood in the wide sense in which it includes "experiment." No philosopher, I think, has ever failed to assume that observation does give a reason for some generalisations—for some propositions which assert that when one kind of thing exists, another generally exists or has existed in a certain relation to it. Even those who, like Hume, imply that observation cannot give a reason for anything, yet constantly appeal to observation in support of generalisations of their own. And even those who hold that observation can give no reason for any generalisation about the relation of one man's perceptions to another's, yet hold that it can give a reason for generalisations about the relation of some to others among a man's own perceptions. It is, indeed, by no means agreed how observation can give a reason for any generalisation. Nobody knows what reason we have, if we have any, for supposing that it can. But that it can, everyone, I think, assumes. I think, therefore, most philosophers will agree, that if we can find any reason at all for generalisations of the kind in which I am interested, a reason for some of them at all events must be found in observation. And what I propose to ask is: What reason can be found in observation for even a single proposition of the kind I have described? for a proposition which asserts that when one man has one kind of perception, another man generally has or has had another.

But, when it is said that observation gives us a reason for generalisations, two things may be meant neither of which I mean. In the first place, we popularly use "observation" in a sense in which we can be said to observe the perceptions, feelings and thoughts of other people: in which, therefore, we can be said to observe the very things with regard to which I am asking what reason we have for believing in their existence. But it is universally[1] agreed that there is a sense in which no man can observe the perceptions, feelings or thoughts of any other man. And it is to this strict sense that I propose to confine the word. I shall use it in a sense, in which we can certainly be said to observe nothing but ourselves, our own perceptions, thoughts and feelings, and what we directly perceive. And in the second place, it may be said that observations made by another person may give me a reason for believing some generalisation. And it is certainly the case that for many of the generalisations in which we all believe, if we have a reason in observation at all, it is not in our own observation that we have it: part of our reason, at all events, lies in things which other people have observed but which we ourselves have not observed. But in asking this particular question, I am not asking for reasons of this sort. The very question that I am asking is: What reason has any one of us for supposing that any other person whatever has ever made any observations? And just as, in the first meaning which I gave to this question, it meant: What thing, that any single man observes is such that it would probably not have existed, unless some other man had made a particular observation? So now I am asking: Which among the things, which one single man observes, are such that they would probably not have existed, unless it were true that some of them generally stood in certain relations to observations of some other person? I am asking: Which among my own observations give me a reason for supposing that some of them are of a kind which are generally preceded or accompanied by observations of other people? Which, for instance, among my own observations give a good reason for the generalisation that when I hear certain words, somebody else has generally had certain particular thoughts, or that whenever anyone hears certain words, somebody else has generally had the thoughts which constitute what we call the meaning of those words? I am asking: Which among the vast series of observations, which any one individual makes during his lifetime, give a good reason for any generalisation whatever of this kind—a generalisation which asserts that some of them are generally preceded by certain thoughts, perceptions or feelings in other persons? I quite admit that there are some generalisations of this kind for which the observations of some particular men will not give a reason. All that I ask is: Is there even one generalisation of this kind, for which the kind of observations, which (as we commonly assume) each man, or nearly every man does make, do give a reason? Among observations of the kind which (as we commonly assume) are common to you and to me, do yours, by themselves, give any reason for even one such generalisation? And do mine, by themselves, give any reason for even one such generalisation? And if they do, which, among these observations, is it which do so?

My question is, then: What reason do my own observations give me, for supposing that any perception whatever, which I have, would probably not occur, unless some other person had a certain kind of perception? What reason do my own observations give me for supposing, for instance, that I should not be perceiving what I do now perceive, unless someone were hearing the sound of my voice? What reason do your own observations give you for supposing that you would not be perceiving just what you are perceiving, unless I were perceiving more or less black marks on a more or less white ground? The question does, I think, appear to be a reasonable one; and most philosophers, I think, have assumed that there is an answer to it. Yet it may be said that there is no answer to it: that my own observations give me no reason whatever for any single proposition of this kind. There are certain philosophers (even apart from thorough sceptics, with whom, as I have said, I am not now arguing) who have denied that they do. There are certain philosophers who hold that nothing which any single one of us observes or can observe, gives the slightest reason for supposing that any of his own perceptions are generally connected with certain perceptions in other people. There are philosophers who hold that the only generalisations for which our own observations do give any warrant are generalisations concerning the manner in which our own perceptions, thoughts and feelings do and probably will succeed one another; and who conclude that, this being so, we have no reason whatever for believing in the existence of any other people. And these philosophers are, I think, right in drawing this conclusion from this premiss. It does not, indeed, follow from their premiss that we have not a reason in the sense which I first explained, and in which, I insisted, it must be admitted that we have a reason. It does not follow that some of our perceptions are not such as would probably not exist, unless some other person had certain perceptions. But, as I have urged, when we say that we have a reason for asserting the existence of something not perceived, we commonly mean something more than this. We mean not only that, since what we perceive does exist, the unperceived thing probably exists too; we mean also that we have some reason for asserting this connection between the perceived and the unperceived. And holding, as we do, that no reason can be given for asserting such a connection, except observation, we should say that, if observation gives no reason for asserting it, we have no reason for asserting it; and having no reason for asserting this connection between the perceived and the unperceived, we should say that we have none either for asserting the even probable existence of the unperceived. This, I think, is what we commonly mean by saying that we have no reason to believe in the existence of a particular thing which we do not perceive. And hence, I think, those philosophers who hold that our own observations give us no reason whatever for any generalisation whatever concerning the connection of any of them with those of other people, are quite right in concluding that we have no reason to assert that any other person ever did have any particular thought or perception whatever. I think that the words of this conclusion, understood in their natural meaning, express precisely what the premiss asserts. We need not, indeed, conclude, as many of these philosophers are inclined to do, that, because we have no reason for believing in the existence of other people, it is therefore highly doubtful whether they do exist. The philosophers who advocate this opinion commonly refute themselves by assigning the existence of other people as part of their reason for believing that it is very doubtful whether any other people exist. That for which we have no reason may, nevertheless, be certainly true. And, indeed, one of the philosophers who hold most clearly and expressly that we do know not only the existence of other people but also that of material objects, is also one of those who deny most emphatically that our own observations can give any reason for believing either in the one or in the other. I refer to Thomas Reid. Reid, indeed, allows himself to use not only the word "observe," but even the word "perceive," in that wide sense in which it might be said that we observe or perceive the thoughts and feelings of others: and I think that the fact that he uses the words in this sense, has misled him into thinking that his view is more plausible and more in accordance with Common Sense than it really is: by using the words in this sense he is able to plead that "observation" really does give a reason for some of those generalisations, for which Common Sense holds that "observation" (in a narrower sense) does give a reason. But with regard to what we observe or perceive, in the strict sense to which 1 am confining those words, he asserts quite explicitly that it gives us no reason either for believing in the existence of material objects or for believing in the existence of other minds. Berkeley, he says, has proved incontrovertibly that it gives us no reason for the one, and Hume that it gives us no reason for the other.

Now these philosophers may be right in holding this. It may, perhaps, be true that, in this sense, my own observations give me no reason whatever for believing that any other person ever has or will perceive anything like or unlike what I perceive. But I think it is desirable we should realise how paradoxical are the consequences which must be admitted, if this is true. It must then be admitted that the very large part of our knowledge, which we suppose to have some basis in experience, is by no means based upon experience, in the sense, and to the extent, which we suppose. We do for instance, commonly suppose that there is some basis in experience for the assertion that some people, whom we call Germans, use one set of words to express much the same meaning which we express by using a different set of words. But, if this view be correct, we must admit that no person's experience gives him any reason whatever for supposing that, when he hears certain words, any one else has ever heard or thought of the same words, or meant anything by them. The view admits, indeed, that I do know that when I hear certain words, somebody else has generally had thoughts more or less similar to those which I suppose him to have had: but it denies that my own observations could ever give me the least reason for supposing that this is so. It admits that my own observations may give me reason for supposing that if anyone has ever had perceptions like mine in some respects, he will also have had other perceptions like others of mine: but it denies that they give me any reason for supposing that any one else has had a perception like one of mine. It admits that my own observations may give me reason for supposing that certain perceptions and thoughts in one person (if they exist) will be followed or preceded by certain other perceptions and thoughts in that person: but it denies that they give me any reason whatever for any similar generalisation concerning the connection of a certain kind of perception in one person with a certain kind of perception in another. It admits that I should not have certain perceptions, which I do have, unless someone else had had certain other perceptions; but it denies that my own observations can give me any reason for saying so—for saying that I should not have had this perception, unless someone else had had that. No observations of mine, it holds, can ever render it probable that such a generalisation is true; no observation of mine can ever confirm or verify such a generalisation. If we are to say that any such generalisation whatever is based upon observation, we can only mean, what Reid means, that it is based on a series of assumptions. When I observe this particular thing, I assume that that particular thing, which I do not observe, exists; when I observe another particular thing, I again assume that a second particular thing, which I do not observe, exists; when I observe a third particular thing, I again assume that a third particular thing, which I do not observe, exists. These assumed facts—the assumed fact that one observation of mine is accompanied by the existence of one particular kind of thing, and that another observation of mine is accompanied by the existence of a different particular kind of thing, will then give me a reason for different generalisations concerning the connection of different perceptions of mine with different external objects—objects which I do not perceive. But (it is maintained) nothing but a mass of such assumptions will give me a reason for any such generalisation.

Now I think it must be admitted that there is something paradoxical in such a view. I think it may be admitted that, in holding it, the philosopher of Common Sense departs from Common Sense at least as far in one direction as his opponents had done in another. But I think that there is some excuse for those who hold it: I think that, in one respect, they are more in the right than those who do not hold it—than those who hold that my own observations do give me a reason for believing in the existence of other people. For those who hold that my observations do give me a reason, have, I believe, universally supposed that the reason lies in a part of my observations, in which no such reason is to be found. This is why I have chosen to ask the question: What reason do my observations give me for believing that any other person has any particular perceptions or beliefs? I wish to consider which among the things which I observe will give such a reason. For this is a question to which no answer, that I have ever seen, appears to me to be correct. Those who have asked it have, so far as I know, answered it either by denying that my observations give me any reason or by pointing to a part of my observations, which, as it seems to me, really do give none. Those who deny are, it seems to me, right in holding that the reason given by those who affirm is no reason. And their correct opinion on this point will, I think, partly serve to explain their denial. They have supposed that if our observations give us any reason at all for asserting the existence of other people, that reason must lie where it has been supposed to lie by those who hold that they do give a reason. And then, finding that this assigned reason is no reason, they have assumed that there is no other.

I am proposing then to ask: Which among the observations, which I make, and which (as we commonly suppose) are similar in kind to those which all or almost all men make, will give a reason for supposing that the existence of any of them is generally connected with the existence of certain kinds of perception or belief in other people? And in order to answer this question, it is obvious we must first consider two others. We must consider, in the first place: Of what nature must observations be, if they are to give a reason for any generalisation asserting that the existence of one kind of thing is generally connected with that of another? And we must consider in the second place: What kinds of things do we observe?

Now to the first of these questions I am not going to attempt to give a complete answer. The question concerning the rules of Inductive Logic, which is the question at issue, is an immensely difficult and intricate question. And I am not going to attempt to say, what kind of observations are sufficient to justify a generalisation. But it is comparatively easy to point out that a certain kind of observations are necessary to justify a generalisation: and this is all that I propose to do. I wish to point out certain conditions which observations must satisfy, if they are to justify a generalisation; without in any way implying that all observations which do satisfy these conditions, will justify a generalisation. The conditions, I shall mention, are ones which are certainly not sufficient to justify a generalisation; but they are, I think, conditions, without which no generalisation can be justified. If a particular kind of observations do not satisfy these conditions, we can say with certainty that those observations give us no reason for believing in the existence of other people; though, with regard to observations which do satisfy them, we shall only be able to say that they may give a reason.

What conditions, then, must observations satisfy, if they are to justify a generalisation? Let us suppose that the generalisation to be justified is one which asserts that the existence of a kind of object, which we will call A, is generally preceded, accompanied, or followed by the existence of a kind of object, which we call B. A, for instance, might be the hearing of a certain word by one person, and B the thought of that which we call the meaning of the word, in another person; and the generalisation to be justified might be that when one person hears a word, not spoken by himself, someone else has generally thought of the meaning of that word. What must I have observed, if the generalisation that the existence of A is generally preceded by the existence of B, is to be justified by my observations? One first point, I think, is plain. I must have observed both some object, which is in some respects like A, and which I will call α, and also some object in some respects like B which I will call β: I must have observed both α and β, and also I must have observed β preceding α. This, at least, I must have observed. But I do not pretend to say how like α and β must be to A and B; nor do I pretend to say how often I must have observed β preceding α, although it is generally held that I must have observed this more than once. These are questions, which would have to be discussed if we were trying to discover what observations were sufficient to justify the generalisation that the existence of A is generally preceded by that of B. But I am only trying to lay down the minimum which is necessary to justify this generalisation; and therefore I am content to say that we must have observed something more or less like B preceding something more or less like A, at least once.

But there is yet another minimum condition. If my observation of β preceding α is to justify the generalisation that the existence of A is generally preceded by the existence of B, it is plain, I think, that both the β and the α, which I observed, must have existed or been real; and that also the existence of β must really have preceded that of α. It is plain that if, when I observed α and β, α existed but β did not, this observation could give me no reason to suppose that on another occasion when A existed, β would exist. Or again, if, when I observed β preceding α, both β and α existed, but the existence of β did not really precede that of α, but, on the contrary, followed it, this observation could certainly give me no reason to suppose that, in general, the existence of A was preceded by the existence of B. Indeed this condition that what is observed must have been real might be said to be included in the very meaning of the word "observation." We should, in this connection, say that we had not observed β preceding α, unless β and α were both real, and β had really preceded α. If I say "I have observed that, on one occasion, my hearing of the word 'moon' was followed by my imagining a luminous silvery disc," I commonly mean to include in my statement the assertion that I did, on that occasion, really hear the word "moon," and really did have a visual image of a luminous disc, and that my perception was really followed by my imagination. If it were proved to me that this had not really happened, I should admit that I had not really observed it. But though this condition that, if observation is to give reason for a generalisation, what is observed must be real, may thus be said to be implied in the very word "observation," it was necessary for me to mention the condition explicitly. It was necessary, because, as I shall presently show, we do and must also use the word "observation" in a sense in which the assertion "I observe A" by no means includes the assertion "A exists"—in a sense in which it may be true that though I did observe A, yet A did not exist.

But there is also, I think, a third necessary condition which is very apt to be overlooked. It may, perhaps, be allowed that observation gives some reason for the proposition that hens' eggs are generally laid by hens. I do not mean to say that any one man's observation can give a reason for this proposition: I do not assume either that it can or that it cannot. Nor do I mean to make any assumption as to what must be meant by the words "hens" and "eggs," if this proposition is to be true. I am quite willing to allow for the moment that if it is true at all, we must understand by "hens" and "eggs," objects very unlike that which we directly observe, when we see a hen in a yard, or an egg on the breakfast-table. I am willing to allow the possibility that, as some Idealists would say, the proposition "Hens lay eggs" is false, unless we mean by it: A certain kind of collection of spirits or monads sometimes has a certain intelligible relation to another kind of collection of spirits or monads. I am willing to allow the possibility that, as Reid and some scientists would say, the proposition "Hens lay eggs" is false, if we mean by it anything more than that: Certain configurations of invisible material particles sometimes have a certain spatio-temporal relation to another kind of configuration of invisible material particles. Or again I am willing to allow, with certain other philosophers, that we must, if it is to be true, interpret this proposition as meaning that certain kinds of sensations have to certain other kinds a relation which may be expressed by saying that the one kind of sensations "lay" the other kind. Or again, as other philosophers say, the proposition "Hens lay eggs" may possibly mean: Certain sensations of mine would, under certain conditions, have to certain other sensations of mine a relation which may be expressed by saying that the one set would "lay" the other set. But whatever the proposition "Hens' eggs are generally laid by hens" may mean, most philosophers would, I think, allow that, in some sense or other, this proposition was true. And they would also I think allow that we have some reason for it; and that part of this reason at all events lies in observation: they would allow that we should have no reason for it unless certain things had been observed, which have been observed. Few, I think, would say that the existence of an egg "intrinsically points" to that of a hen, in such a sense that, even if we had had no experience of any kind concerning the manner in which objects like eggs are connected with animals like hens, the mere inspection of an egg would justify the assertion: A hen has probably existed.

I assume, then, that objects having all the characteristics which hens' eggs have (whatever these may be) are generally laid by hens (whatever hens may be); and I assume that, if we have any reason for this generalisation at all, observation gives us some reason for it. But now, let us suppose that the only observations we had made were those which we should commonly describe by saying that we had seen a hen laying an egg. I do not say that any number of such observations, by themselves, would be sufficient to justify our generalisation: I think it is plain that they would not. But let us suppose, for the moment, that we had observed nothing else which bore upon the connection between hens and eggs; and that, if therefore our generalisation was justified by any observations at all, it was justified by these. We are supposing, then, that the observations which we describe as "seeing hens lay eggs" give some reason for the generalisation that eggs of that kind are generally laid by hens. And if these observations give reason for this, obviously in a sense they give reason for the generalisation that the existence of such an egg is generally preceded by that of a hen; and hence also, they give us reason to suppose that if such an egg exists, a hen has probably existed also—that unless a hen had existed, the egg would not have existed. But the point to which I wish to call attention is that it is only in a limited sense that they do give reason for this. They only give us reason to suppose that, for each egg, there has existed a hen, which was at some time near the place where the egg in question then was, and which existed at a time near to that at which the egg began to exist. The only kind of hens, whose existence they do give us reason to suppose, are hens, of which each was at some time in spatial and temporal proximity (or, if Idealists prefer, in the relations which are the "intelligible counterparts" of these) to an egg. They give us no information at all about the existence of hens (if there are any) which never came within a thousand miles of an egg, or which were dead a thousand years before any egg existed. That is to say, they do give us reason to suppose that, if a particular egg exists, there has probably existed a hen which was at some time near that egg; but they give us no reason to suppose that, if a particular egg exists, there must have existed a hen which never came near that egg. They do give us reason to suppose that, for each egg, there has probably existed a hen which at some time stood to the egg in question in that relation which we have observed to hold between an egg and a hen, when we observed the hen laying an egg. But they give us no reason to infer from the existence of an egg any other kind of hen: any hen which never stood to the egg in the relation in which we have observed that some hens do stand to eggs.

What I wish to suggest is that this condition is a universal condition for sound inductions. If the observation of β preceding α can ever give us any reason at all for supposing that the existence of A is generally preceded by that of B, it can at most only give us reason to suppose that the existence of an A is generally preceded by that of a B which stands to our A in the same relation in whichβ has been observed to stand to α. It cannot give the least reason for supposing that the existence of an A must have been preceded by that of a B, which did not stand to A in the observed relation, but in some quite different one. If we are to have any reason to infer from the existence of an A the existence of such a B, the reason must lie in some different observations. That this is so, in the case of hens' eggs and hens, is, I think, obvious: and, if the rule is not universal, some reason should at least be given for supposing that it does apply in one case and not in another.

Having thus attempted to point out some conditions which seem to be necessary, though not sufficient, where observation is to give any reason for a generalisation, I may now proceed to my second preliminary question. What kinds of things do we observe?

In order to illustrate how much and how little I mean by "observation" or "direct perception," I will take as an instance a very common visual perception. Most of us are familiar with the experience which we should describe by saying that we had seen a red book and a blue book side by side upon a shelf. What exactly can we be said to observe or directly perceive when we have such an experience? We certainly observe one colour, which we call blue, and a different colour, which we call red; each of these we observe as having a particular size and shape; and we observe also these two coloured patches as having to one another the spatial relation which we express by saying they are side by side. All this we certainly see or directly perceive now, whatever may have been the process by which we have come to perceive so much. But when we say, as in ordinary talk we should, that the objects we perceive are books, we certainly mean to ascribe to them properties, which, in a sense which we all understand, are not actually seen by us, at the moment when we are merely looking at two books on a shelf two yards off. And all such properties I mean to exclude as not being then observed or directly perceived by us. When I speak of what we observe, when we see two books on a shelf, I mean to limit the expression to that which is actually seen. And, thus understood, the expression does include colours, and the size and shape of colours, and spatial relations in three dimensions between these patches of colour, but it includes nothing else.

But I am also using observation in a sense in which we can be said actually to observe a movement. We commonly say that we can sometimes see a red billiard ball moving towards a white one on a green table. And, here again, I do not mean to include in what is directly perceived or observed, all that we mean by saying that the two objects perceived are billiard-balls. But I do mean to include what (we should say) we actually see. We actually see a more or less round red patch moving towards a more or less round white patch; we see the stretch of green between them diminishing in size. And this perception is not merely the same as a series of perceptions—first a perception of a red patch with a green stretch of one size between it and the white; then a perception of a red patch with a green stretch of a different size between it and the white; and so on. In order to perceive a movement we must have a different perception from any one of these or from the sum of them. We must actually see the green stretch diminishing in size.

Now it is undoubtedly difficult, in some instances, to decide precisely what is perceived in this sense and what is not. But I hope I have said enough to show that I am using "perceive" and "observe" in a sense in which, on a given occasion, it is easy to decide that some things certainly are perceived, and other things, as certainly, are not perceived. I am using it in a sense in which we do perceive such a complex object as a white patch moving towards a red one on a green field; but I am not using it in any sense in which we could be said to "perceive" or "observe" that what we saw moving was a billiard-ball. And in the same way I think we can distinguish roughly between what, on any given occasion, we perceive, as we say, "by any one of the other senses," and what we do not perceive by it. We can say with certainty that, on any given occasion, there are certain kinds of "content" which we are actually hearing, and others which we are not actually hearing; though with regard to some again it is difficult to say whether we are actually hearing them or not. And similarly we can distinguish with certainty in some instances, between what we are on a given occasion, actually smelling or feeling, and what we are not actually smelling or feeling.

But now, besides these kinds of "things," "objects," or "contents," which we perceive, as we say, "by the senses," there is also another kind which we can be said to observe. Not only can I observe a red and blue book side by side; I can also observe myself observing them. I can perceive a red patch moving towards a white, and I can also perceive my perception of this movement. And what I wish to make as plain as I can is that my perception of the movement of a coloured patch can at least be distinguished from that movement itself. I wish to make it plain that to observe a coloured patch moving is to observe one thing; and to observe myself observing a coloured patch moving is another. When I observe my own perception of a movement, I observe something more than when I merely observe the movement, and something very different from the movement. I may perceive a red and a blue book side by side on a shelf; and at another time I may perceive a red ball moving towards a white. The red and blue patch, of one shape, at rest side by side, are different from the red, of another shape, moving towards the white; and yet, when I say that both are "perceived," I mean by "perceived" one and the same thing. And since, thus, two different things may both be perceived, there must also be some difference between each of them and what is meant by saying that it is perceived. Indeed, in precisely the same way In which I may observe a spatial relation between a red patch and a blue (when I observe them "side by side") I do, when I observe my own perception of them, observe a spatial relation between it and them. I observe a distance between my perception and the red and blue books which I perceive, comparable in magnitude with the breadth or height of the blue book, just as these are comparable in magnitude with one another. And when I say I observe a distance between my perception of a red book and that red book itself, I do not mean that I observe a distance between my eyes, or any other part of what I call my body, and the red patch in question. I am talking not of my eyes, but of my actual perception. I observe my perception of a book to be near the book and further from the table, in exactly the same sense in which I observe the book to be near the shelf on which it stands, and further from the table. And just as, if the distance between a red patch and a white is to be perceived, the red patch must be different from the white, so, if I perceive a certain distance between my perception and the red patch, my perception must be different from the red patch which I perceive.

I assume, then, that we observe, on the one hand, coloured patches of certain shapes and sizes, and their spatial relations to one another, together with all the other kinds of "contents," which we should usually be said to perceive "through the senses." And, on the other hand, we also sometimes observe our own perceptions of such "contents" and our thoughts. And these two kinds of "content" are different from one another: my perception of a red patch with gold letters on it, is not itself a red patch with gold letters on it; and hence, when I observe my perception of this patch, I observe something different from that which I observe when I merely perceive the patch. Either of these two kinds of "content"—either colours, moving or at rest, sounds, smells, and all the rest—or, on the other hand, my perceptions of these—either of these two kinds, or both, might conceivably, since both are observed, give grounds for a generalisation concerning what exists. But, as I have said, if observations are to give any ground for such a generalisation, it must be assumed that what Is observed exists or is real. And since, as I have insisted, when I observe my perception of a red patch with gold letters on it, I observe something different from what I observed when I merely observed a red patch with gold letters on it, it follows that to assume the existence of my perception of this red and gold is not the same thing as to assume the existence of the red and gold itself.

But what, it may be asked, do I mean by this property of "existence" or "reality," which may, it would seem, belong to every content, which I observe, or may again belong to none, or which may belong to some and not to others? What is this property which may belong to my perception of a movement, and yet not belong to the movement perceived, or which may again belong to the movement perceived and not to my perception of it, or which may again belong to both or to neither?

It is necessary, I think, to ask this question at this point, because there are some philosophers who hold that, in the case of some kinds of "content," at all events, to say that they "exist" is to say that they are "perceived." Some hold that to say "A exists" is to say neither more nor less than "A is perceived"—that the two expressions are perfect synonyms; and others again would say that by "A exists or is real" we may mean more than that "A is perceived," but that we must at least mean this. Now, I have hitherto used the word "existence" pretty freely, and I think that, when I used it, I used it in its ordinary sense. I think it will generally have suggested to you precisely what I meant to convey, and I think that, in some cases at all events, it will not even have occurred to you to doubt whether you did understand what I meant by it. But, if these philosophers are right, then, if you have understood what I meant by it, I have all along been using it in a sense, which renders the end of my last paragraph perfect nonsense. If these philosophers are right, then, when I assert that what is perceived may yet not exist, I am really asserting that what is perceived may yet not be perceived—I am contradicting myself. I am, of course, quite unaware that I am doing so. But these philosophers would say either you are contradicting yourself, or you are not using the word "exists" in its ordinary sense. And either of these alternatives would be fatal to my purpose. If I am not using the word in its ordinary sense, then I shall not be understood by anyone; and, if I am contradicting myself, then what I say will not be worth understanding.

Now, with one class of these philosophers—the class to which, I think, Berkeley belongs—I think I can put myself right comparatively easily. The philosophers I mean are those who say that it is only in the case of one particular class of "contents" (the kind of "content" which Berkeley calls "ideas") that to say "the 'content' A exists" is to say "A is perceived," and who admit that in the case of other contents—myself and my perceptions and thoughts, for example—to say that these exist or are real, is to say of them something different from this. These philosophers admit, that is to say, that the word "exists" has two different senses: and that in only one of these senses is it synonymous with the words "is perceived." When (they hold) I say of such a content as a red patch with gold letters on it that it "exists" I do mean that it is perceived; but when I say of my perception of such a patch that it exists, I do not mean that my perception is perceived but something different from this. Now, it would be nothing strange that one and the same word should be used in two different senses; many words are used in many different senses. But it would, I think, be something very strange indeed, if in the case of a word which we constantly apply to all sorts of different objects, we should uniformly apply it to one large class of object in the one sense and the one sense only and the other large class in the other sense and the other sense only. Usually, in the case of such ambiguous words, it happens that, in different contexts, we apply it to one and the same object in both senses. We sometimes wish to say of a given object that it has the one property, and sometimes we wish to say of the same object that it has the other property; and hence we apply the same word to the same object, at one time in one sense, and at another in the other. I think, therefore, that, even if there were these two different senses of the word "existence," it would be very unlikely that we should not commonly, in some contexts, apply it in the sense, in which (as is alleged) it does apply to perceptions, to "contents" which are not perceptions. Indeed, I think, it is quite plain that we constantly do ask, with regard to what is not a perception, whether it exists, in precisely the same sense, in which we ask, with regard to a perception, whether it exists. We ask in precisely the same sense: Was the Roc a real bird, or merely an imaginary one? and, did Sindbad's perception of the Roc really exist, or is it a fiction that he perceived a Roc? I think, therefore, that the sense in which these philosophers admit that we do apply the word "existence" to perceptions, is one in which we also commonly apply it to "contents" other than perceptions. But, even if this is not the case, I can set myself right with them by a simple explanation. I need merely explain that the sense in which I am proposing to enquire whether a red patch exists, is precisely the sense in which they admit that my perception of a red patch does exist. And in this sense, it is plain that to suppose that a thing may exist, which is not perceived, or that it may not exist, although it is perceived, is at least not self-contradictory.

But there may be other philosophers who will say that, in the case of a perception also, to say that it exists or is real is to say that it is perceived—either that alone or something more as well. And to these philosophers I would first point out that they are admitting that the proposition "This perception is real" is significant. There is some sense or other in which we may say: "Alexander's perception of an elephant was real or did exist, but Sindbad's perception of a Roc was not real—never did exist": the latter proposition is, in some sense or other, not self-contradictory. And then I would ask of them: When they say, that to call a perception "real" is to assert that it is perceived, do they mean by this that to call it real is to assert that it is really perceived, or not? If they say "No," then they are asserting that to call a perception "real" is merely to say that it was perceived in the sense in which Sindbad did perceive a Roc: they are asserting that to call it "real" is not to say, in any sense, that it was really perceived: they are asserting that to call a perception "real" is to say that it was perceived, in some sense quite other than that in which we ordinarily use the word: for we certainly commonly mean, when we say "A was perceived," that a perception of A was "real": we should commonly say that Sindbad did not perceive a Roc—meaning that no such perception ever did exist. I do not think they do mean this; and, in any case, if they do, I think it is plain that they are wrong. When we say that a perception is "real," we certainly do not mean merely that it is the object of another perception, which may itself be quite unreal—purely Imaginary. I assume, therefore, that when they say: To call a perception "real" is to say that it is perceived; they mean, what we should naturally understand, namely, that: To call it "real" is to say that it is really perceived—to say that it is the object of another perception, which is also real in the same sense. And, if they mean this, then what they say is certainly untrue. Their definition of reality is circular. It cannot be the case that the only sense in which a perception may be said to be real, is one in which to call it so is to assert that not it alone, but another perception is real also. It cannot be the case that the assertion "A is real" is identical with the assertion "A and B are both real," where A and B are different, and "real" is used in the same sense as applied to both. If it is to be true that the assertion "A is real" ever, in any sense, includes the assertion "A is really perceived," there must be another sense of the word "real," in which to assert "A is real" is to assert less than "A is really perceived"—the sense, namely, in which we here assert that the perception of A is real.

We find, therefore, that the other class of philosophers were at least right in this: they were right in allowing that the sense in which we commonly say that our perceptions exist is one in which "exist" does not include, even as a part of its meaning, "is perceived." We find that there is a common sense of the word "existence," in which to say "A exists" must mean less than "A is really perceived": since, otherwise, the only possible definition of the word "existence" would be a circular definition. And I may point out that two other definitions, which have been sometimes suggested by philosophers as giving what we commonly mean by "reality" or "existence" are vitiated by the same fault—they also are circular. Some philosophers have sometimes suggested that when we call a thing "real," we mean that it is "systematically connected" in some way with other things. But, when we look into their meaning, we find that what they mean is (what, indeed, is alone plausible)—systematically connected with other real things. And it may possibly be the case that we sometimes use the word "real" in this sense: but, at least, it must be certainly the case, that, if we do, we also use it in another and simpler sense—the sense in which it is employed in the proposed definition. And other philosophers have suggested that what we mean by "real" is—"connected in some way with a purpose—helping or hindering, or the object of a purpose." But if we look into their meaning, we find they mean—connected with a real purpose. And hence, even if we do sometimes mean by "real," "connected with a real purpose," it is plain we also sometimes mean by "real" something simpler than this—that namely, which is meant by "real" in the proposed definition.

It is certain, therefore, that we do commonly use the word "existence" in a sense, in which to say "A exists" is not to say "A is perceived," or "A is systematically connected with other real things," or "A is purposive." There is a simpler sense than any of these—the sense in which we say that our own perceptions do exist, and that Sindbad's perceptions did not exist. But when I say this, I am by no means denying that what exists, in this simple sense, may not always also exist in all the others; and that what exists in any of them may not also always exist in this. It is quite possible that what exists is always also perceived, and that what is perceived always also exists. All that I am saying is that, even if this is so, this proposition is significant—is not merely a proposition about the meaning of a word. It is not self-contradictory to suppose that some things which exist are not perceived, and that some things which are perceived do not exist.

But, it may be asked: What is this common simple sense of the word "exists"? For my own part, it seems to me to be so simple that it cannot be expressed in other words, except those which are recognised as its synonyms. I think we are all perfectly familiar with its meaning: it is the meaning which you understood me to have throughout this paper, until I began this discussion. I think we can perceive at once what is meant by asserting that my perception of black marks on a white ground is "real," and that no such perception as Sindbad's of a Roc was ever "real": we are perfectly familiar with the property which the one perception is affirmed to possess, and the other to be without. And I think, as I have said, that this property is a simple one. But, whatever it is, this, which we ordinarily mean, is what I mean by "existence" or "reality." And this property, we have seen, is certainly neither identical with nor inclusive of that complex one which we mean by the words "is perceived."

I may now, then, at last approach the main question of my paper. Which among the "contents" which I observe will give me reason to suppose that my observation of some of them is generally preceded or accompanied or followed by the existence of certain particular perceptions, thoughts or feelings in another person? I have explained that the "contents" which I actually observe may be divided into two classes: on the one hand, those which, as we commonly say, we perceive "through the senses"; and, on the other hand, my perceptions of these last, my thoughts, and my feelings. I have explained that if any of these observed contents are to give reason for a generalisation about what exists, they must exist. And I have explained that with regard to both classes of "contents" I am using the word "exist" in precisely the same sense—a sense, in which it is certainly not self-contradictory to suppose that what is perceived, does not exist, and that what is not perceived, does exist; and, in which, therefore, the assumption that a red patch with gold letters on it exists, is a different assumption from the assumption that my perception of a red patch with gold letters on it exists; and the assumption that my perception of a red patch with gold letters on it exists, is a different assumption from the assumption that a red patch with gold letters on it exists.

What, then, that we observe, can give us any reason for believing that anyone else has certain particular perceptions, thoughts or feelings? It has, I think, been very commonly assumed that the observation of my own perceptions, thoughts, and feelings, can, by itself, give me such a reason. And I propose, therefore, to examine this assumption. If, as I hope to show, it is false; it will then follow, that if our own observation gives us any reason whatever, for believing in the existence of other persons, we must assume the existence, not only of our own perceptions, thoughts and feelings, but also of some, at least, among that other class of data, which I may now, for the sake of brevity, call "sense-contents"; we must assume that some of them exist, in precisely the same sense in which we assume that our perceptions, thoughts, and feelings exist.

The theory which I propose to examine is, then, the following. My observation of my own thoughts, feelings, and perceptions may, it asserts, give me some reason to suppose that another person has thoughts, feelings, and perceptions similar to some of mine. Let us assume, accordingly, that my own thoughts, feelings, and perceptions do exist; but that none of the "sense-contents," which I also observe, do so. Where among my perceptions am I to look for any which might conceivably give me a reason for supposing the existence of other perceptions similar to my own? It is obvious where I must look. I have perceptions which I call perceptions of other people's bodies; and these are certainly similar in many respects to other perceptions of my own body. But I also observe that certain kinds of perceptions of my own body are preceded by certain other perceptions, thoughts, or feelings of mine. I may, for instance, observe that when I perceive my hand suddenly catch hold of my foot in a particular way, this perception was preceded by a particular kind of feeling of pain. I may, perhaps, observe this often enough to justify the generalisation that the perception of that particular motion of my body is generally preceded by that particular feeling of pain. And in this way I may perhaps have reason for quite a number of generalisations which assert that particular kinds of perceptions of my own body are generally preceded by other particular kinds of perceptions, thoughts, or feelings of my own.

But I may also, no doubt, have the perception, which I call the perception of another person's hand catching hold of his foot, in a manner similar to that in which I have perceived my own hand catch hold of my own foot. And my perception of another person's hand catching hold of his foot may undoubtedly be similar in many respects to my perception of my own hand catching hold of my own foot. But I shall not observe the same kind of feeling of pain preceding my perception of his hand catching hold of his foot, which I have observed preceding my perception of my hand catching hold of my foot. Will my generalisation, then, give me any reason to suppose that nevertheless my perception of his hand catching hold of his foot is preceded by a similar feeling of pain, not in me but in him? We undoubtedly do assume that when I perceive another person's body making movements similar to those which I have observed my own body making, this perception has generally been preceded by some feeling or perception of his similar to that which I have observed to precede my perception of similar movements in my own body. We do assume this; and it is precisely the kind of generalisation, which, I have insisted, must be admitted to be true. But my present question is: Will such observations as I have described give any reason for thinking any such generalisation true? I think it is plain that they will not give the slightest reason for thinking so. In the first place, all the perceptions which I call perceptions of another person's body differ very considerably from any of those which I call perceptions of my own. But I am willing to waive this objection. I am not offering any theory as to what degree of likeness is sufficient to justify a generalisation: and therefore I will allow that the degree of likeness may be sufficient. But there remains an objection which is, I think, quite fatal to the proposed inference. This objection is that the inference in question plainly does not satisfy the third condition which I suggested above as necessary, wherever any generalisation is to be justified by observation. I am willing to allow that my observations of the fact that my perception of a certain movement in my own body is preceded by a certain feeling of pain, will justify the generalisation that my perception of any such movement, whether in my own body or in that of another person, is generally preceded by a similar feeling of pain. And I allow, therefore, that when I perceive a certain movement in another's body, it is probable that the feeling of pain exists, though I do not perceive it. But, if it is probable that such a feeling of pain exists, such a feeling must stand in the same relation to my perception of the movement in another person's body, in which a similar feeling of pain has been observed by me to stand to my perception of such a movement in my own body. That is to say the only kind of feeling of pain, which my observations do justify me in inferring, if (as I admit they may) they justify me in inferring any at all, is a feeling of pain of my own. They cannot possibly justify the belief in the existence of any such feeling except one which stands to my perception in the same relation in which my feelings do stand to my perceptions—one, that is to say, which is my own. I have no more reason to believe that the feeling of pain which probably precedes my perception of a movement in another person's body can be the feeling of another person, than, in my former example, I had reason to suppose that the hen, whose existence probably preceded that of a given egg, could be a hen, which had never been near the egg in question. The two cases are exactly analogous. I observe a feeling of pain of my own preceding a perception of my own. I observe the two, that is to say, as standing to one another, in those relations (whatever they may be) in which any perception of mine stands to any other thought, perception or feeling of mine, and which are, at all events, different from any relation in which a perception or feeling of another person can stand to one of mine. I never perceive the feeling and the perception as standing in any other relation. In any case, therefore, where I do observe something like the perception, but do not observe the feeling, I can only be justified (if justified in inferring any feeling at all), in inferring an unperceived feeling of my own.

For this reason I think that no observations of my own perceptions, feelings or thoughts can give me the slightest reason for supposing a connection between any of them and any feeling, perception, or thought in another person. The argument is perfectly general, since all my perceptions, feelings and thoughts do have to one another those relations in virtue of which I call them mine; and which, when I talk of a perception, feeling or thought as being another persons, I mean to say that it has not got to any of mine. I can, therefore, merely from observation of this class of data never obtain the slightest reason for belief in the existence of a feeling, perception, or thought which does not stand in these relations to one of mine—which is, that is to say, the feeling, perception or thought, of another person. But how different is the case, if we adopt the hypothesis, which I wish to recommend—if we assume the existence of that other class of data which I have called "sense-contents!" On this hypothesis, that which I perceive, when I perceive a movement of my own body, is real; that which I perceive when I perceive a movement of another's body is real also. I can now observe not merely the relation between my perception of a movement of my body and my own feelings, but also a relation between a real movement of my body and my own feelings. And there is no reason why I should not be justified in inferring that another person's feelings stand in the same relation to the real movements of his body, in which I observe my own feelings to stand to similar real movements of mine.

But there is another argument which may still be urged by those who hold that my own perceptions, thoughts, and feelings, by themselves, may be sufficient to justify a belief in the existence of other persons. It may be said: "Our observation of our own perceptions may be sufficient to verify or confirm the hypothesis that other persons exist. This hypothesis is one which "works." The assumption that other persons have particular thoughts, feelings and perceptions enables us to predict that they will have others and that our own perceptions will be modified accordingly: it enables us to predict future perceptions of our own; and we find that these predictions are constantly verified. We observe that we do have the perceptions, which the hypothesis leads us to expect we should have. In short, our perceptions occur just as they would do, if the hypothesis were true; our perceptions behave as if other persons had the perceptions, thoughts and feelings which we suppose them to have. Surely, then, they confirm the truth of the hypothesis—they give some reason to think it probably true?"

All this, which I have supposed an opponent to urge, I admit to be true. I admit that the fact that an hypothesis works may give some reason to suppose it true. I admit that my perceptions occur just as they would do, if other people had the perceptions which I suppose them to have. I admit that that assumption enables me to make predictions as to future perceptions of my own, and that I observe these predictions to come true. I admit all this. But I admit it only in a sense in which it in no way conflicts with the position which I am maintaining. The words, which I have put into the mouth of a supposed opponent, may, in fact, mean three different things, which it is worth while to distinguish. In two of those meanings, which I shall admit to be true and which are what make them seem plausible, they do not deny what I assert. Only in the third sense are they an objection to my position: and in that sense they are false.

One of the meanings which I admit to be true is as follows:—I have not only admitted but insisted that some of my perceptions are just such as would occur if another person had certain particular feelings: I have insisted that I should not have just those perceptions which I do have, unless some other person had certain feelings and perceptions which I suppose him to have. And I admit further that the fact that I have one of the perceptions in question—for instance, that of another person's hand catching hold of his foot—this fact, together with the true assumption that I should not have this perception, unless some other person felt pain, will justify the assertion that another person has felt pain. In this sense, I admit, the fact that I perceive what I do perceive will give me reason to suppose that another person has felt pain. And, on the other hand, I also admit that the fact that I have this perception, together with the true assumption that when I have it another person has felt pain, may help to justify the assumption that the perception in question is one which I should not have had unless another person had felt pain—it helps to justify the generalisation that certain of my perceptions are just what would occur, if another person had felt pain. In general terms, that is to say, I admit that the occurrence of B, together with the assumption that B is just the sort of thing which would occur if A existed, will justify the assertion that A exists in that particular instance. And I also admit that the occurrence of B, together with the assumption that A exists in that particular instance, may help to justify the assumption that B is just the sort of thing which would exist, if A existed. In other words: When it is said that the observation of B's existence confirms or verifies the assumption that A exists, either of two things may be meant. It may be meant that, assuming B to be the sort of thing which would exist if A existed, the observation of B confirms the assumption that A exists in this particular instance. Or, on the other hand, it may be meant that, assuming A to exist in this particular instance, the observation of B may confirm the generalisation, that B is just the sort of thing which would exist, if A existed. Either the one or the other of these two things is, I think, what is generally assumed, when it is assumed that what we do observe confirms or verifies the assumption that there exists some particular thing which we don't observe. And I am admitting that both these assumptions are true.

But neither of them conflicts in any way with the position I am maintaining. What I am maintaining is that no observation of my own perceptions, by itself, can confirm the generalisation that any one of them is just what would occur if another person had a particular feeling. I admit this generalisation to be true; and I admit that my observation of my own perceptions and feelings may give me reason to suppose that if another person has certain perceptions or feelings he will also have certain others. What I deny is that they give me the slightest reason to suppose that the existence of any such feeling or perception in another has any connection with the existence of any perception of my own—to suppose that any perception of my own is the sort of thing which would occur if another person had a particular feeling. What therefore, my opponent must affirm is that the observation of a perception of my own without the assumption (which Reid makes) that in that particular instance any feeling or perception of another person, of any kind whatever, has preceded it, may give me reason to suppose that that perception of my own is of a kind which is generally preceded by a particular kind of feeling in another person. And this, I think, is plainly false.

But there is yet a third thing which may be meant, and which I am willing to admit may be true. It may be said: "I believe many generalisations of the following kind. I believe that when I have a perception A, some other person has generally had a feeling X; I believe that the existence of the feeling X is generally followed, in the same person, by that of the feeling Y; and I believe also that when another person has the feeling Y, I generally have the perception B. I believe all this." And it must, I think, be admitted that we do believe generalisations of this kind, and generalisations in which there are not merely two steps between A and B, but a great number of steps. "But then," it may be said, "my belief in this generalisation causes me, when I observe my perception A, to expect that I shall have the perception B; and such expectations, I observe, are constantly realised." And this also, I think, must be admitted to be true. "But, finally," it may be said, "beliefs which produce expectations which are constantly realised are generally true. And hence the fact that these beliefs of mine about the connection of feelings in other persons with perceptions of my own do lead to expectations which are realised, gives me reason to suppose that these generalisations are true and hence that other persons do have particular kinds of feelings." And I am willing to admit that this also is true. I am willing to admit that true predictions can, as a rule, only be produced by true beliefs. The generalisation that this is so, is, indeed, one which can only be justified by the observations of beliefs, which are, in some way, independently proved to be true; and hence, if it is to be justified, without assuming the existence of anything other than my own perceptions, thoughts, and feelings, it can only be justified by my observation that beliefs with regard to the manner in which these succeed one another generally lead to true predictions. Whether the observation of such beliefs alone could give sufficient reason for it, is, I think, doubtful; but I am willing to admit that it may be so. One thing, however, is, I think, quite plain: namely, that this generalisation "Beliefs which lead to true predictions are generally true" cannot be true, unless some other of the "contents" which I observe, beside my own perceptions, thoughts, and feelings, do exist. That is to say, in giving a reason for supposing the existence of other people, this generalisation also gives a reason for the very theory which I am advocating, namely, that some of those data which I have called "sense-contents" do exist. It does this, because it is quite certain that beliefs in generalisations about the existence of sense-contents can (and do) constantly lead to true predictions. The belief that when I have observed a fire of a certain size in my grate, something similar to what I have observed will continue to exist for a certain time, can, and constantly does, lead to the true prediction that, when I come back to my room in half an hour's time, I shall observe a fire of a certain size still burning. We make predictions on such grounds, I think, every day and all day long. And hence unless such beliefs as that what I observe when I see a fire burning does exist, are true, we certainly have no reason to suppose that beliefs which lead to true predictions are generally true. And hence on this hypothesis also it remains true: that, unless some of the contents which I observe other than my own perceptions, thoughts, and feelings, do exist, I cannot have the slightest reason for supposing that the existence of certain perceptions of my own is generally connected with that of certain perceptions, thoughts, or feelings in any other person.

I conclude therefore that, unless some of the observed data which I have called sense-contents do exist, my own observations cannot give me the slightest reason for believing that anybody else has ever had any particular perception, thought, or feeling. And, having arrived so far towards an answer to my first question: How do we know that any other persons exist? I may now point out that precisely the same answer must be given to my second question: How do we know that any particular kind of thing exists, other than ourselves, our perceptions, thoughts, and feelings, and what we directly perceive? There is a view concerning what exists, which deserves, I think, much more respect than it generally receives from philosophers nowadays. The view I mean is the view that material objects, such as they are conceived by physical science, do really exist. It is held by some persons (and Reid is among them) that we do know of the existence, not only of other persons, but also of the movements of matter in space. It is held that we do know, with considerable precision, what kinds of movements of matter generally precede my perception, when I have a particular perception. It is held, for instance, that when I perceive a red and blue book side by side on a shelf, at a certain distance from me, there have existed, between two material objects, which may be called books, and another kind of material object, which may be called my eyes, certain wave-like motions of a material medium; that there have existed two different sets of waves, of which the one is connected with my perception of red and the other with my perception of blue; and that the relative heights and breadths of the two different sets of waves, and the relative velocity of their movements are very exactly known. It is held that some men have a vast amount of very precise information about the existence of objects of this kind; and I think the view that this is so deserves a great deal of respect. But what I wish now to point out is that no one's observation of his own perceptions, thoughts and feelings, can, by itself, give him the slightest reason for believing in the existence of any such material objects. All the arguments by which I have tried to show that this kind of observation alone can give me no reason to believe in the existence of any kind of perception or feeling in another person, apply, with at least equal force, to show that it can give me no reason to believe in the existence of any kind of material object. On the other hand, if we are to admit the principle that "Beliefs which lead to true predictions, are generally true," this principle will give us at least as much reason to believe in the existence of certain kinds of material objects as to believe in the existence of other persons; since one of the most remarkable facts about beliefs in the existence of such objects is that they do so often lead to true predictions. But it must be remembered that we can have no reason for believing this principle itself, unless our own perceptions, thoughts and feelings are not the only kind of observed "content" which really does exist: we can have no reason for it, unless some such things as what I perceive, when I see a red and blue book side by side, do really exist.

It would seem, therefore, that if my own observations do give me any reason whatever for believing in the existence either of any perception in any other person or of any material object, it must be true that not only my own perceptions, thoughts and feelings, but also some of the other kinds of things which I directly perceive—colours, sounds, smells, etc.—do really exist: it must be true that some objects of this kind exist or are real in precisely the same simple sense in which my perceptions of them exist or are real. Is there then any reason to think that this is not true? Is there any reason to think, for instance, that none of the colours which I perceive as occupying areas of certain shapes and sizes really exist in the areas which they appear to occupy? This is a question which I wished to discuss at length, because I think that it is one in which there are real difficulties. But I have given so much space to other questions, that I can only deal with it very briefly here.

Some philosophers are very fond of asserting that a colour cannot exist except when it is perceived; and it might possibly be thought that when I suggest that colours do really exist, I am suggesting that they do exist when they are not perceived. I wish, therefore, briefly to point out that the question whether anything does exist, when it is not perceived, is one which I have not argued and shall not attempt to argue in this paper. I have, indeed, tried to show that since "exists" does not mean "is perceived," it is, at least, conceivable that things should exist, when they are not perceived. But I have admitted that it is quite possible none do so: it may be the case that whenever a thing exists, it is also at the same time perceived, for anything that I have said or shall say to the contrary. I think, indeed, that, if such things as colours do exist, my observation of their behaviour will justify me in concluding that they also exist when I myself am, at least, not aware of perceiving them: but since I have not attempted to determine what kinds of observation are sufficient to justify a generalisation, I do not pretend to say whether this is so or not: and still less do I pretend to say whether, if they exist when I do not perceive them, we are justified in supposing that someone else must be perceiving them. The question whether anything exists, when it is not perceived, and, if so, what things, seems to me to be one which can only be settled by observation; and thus, I conceive, observation might justify us in concluding that certain kinds of things—pains, for example, do not exist, when they are not perceived and that other kinds of things—colours, for example, do exist, when they are not perceived. The only way, in which, so far as I am aware, the theory I am advocating does conflict with ordinary Idealistic conclusions, is that it does suggest that things, which are not "spiritual," do sometimes exist, as really and as truly, as things which are.

The theory, therefore, that nothing exists, except when it is perceived, is no objection (even if it be true) to the supposition that colours do exist. What objections are there to this supposition? All serious objections to it are, I think, of one type. They all rest upon the assumption that, if a certain kind of thing exists at a certain time in a certain place, certain other kinds of things cannot exist at the same time in the same place. They are all, that is to say, of the same type as Berkeley's argument: that, though the same body of water may appear to be simultaneously both hot and cold (if one of the hands we plunge into it is warm and the other cold), yet the heat and the cold cannot both really be in the same body at the same time. And it is worth noticing that anyone who uses this argument must admit that he understands what is meant by "really existing in a given place," and that he means by it something other than "being perceived as in a given place." For the argument itself admits that both the heat and the cold are really perceived as being in the same place, and that there is no difficulty in supposing that they are so; whereas It urges that there is a difficulty in supposing that they both really exist in it.

Now there is one obvious defect in this type of argument, if designed to prove that no sensible quality exists at any place where it is perceived as being—a defect, which Berkeley himself admits in his "Principles," though he omits to notice it where he repeats the argument in his "Hylas." Even if we assume that the heat and the cold cannot both exist in the same place (and I admit that, in this case, the contrary assumption does seem repugnant to Common Sense), it does not follow that neither exists there. That is to say this type of argument, even if we grant its initial assumption, will only entitle us to conclude that some sensible qualities which we perceive as being in a certain place at a certain time, do not exist in that place at that time. And this conclusion, I am inclined to think, is true. In the case, for instance, of the so-called "images" which we perceive in a looking-glass, we may very readily admit that the colours and shapes which we perceive do not exist at the places where they appear to be—namely at various distances behind the glass. But yet, so far as I can see, we have no reason whatever for supposing that they do not, except the assumption that our observations give us reason to believe that other sensible qualities do exist in those positions behind the glass; and the assumption that where these other sensible qualities do exist, those which we see in the glass do not exist. I should, therefore, admit that some sensible qualities which we perceive as being in certain places, do not exist in those places, while still retaining my belief that others do. And perhaps this explanation is the one which should also be adopted in the case of sensible qualities which appear to be at a great distance from us. When, for instance, (as we say), "we see the moon," what we perceive (if the moon be full) is a round bright silver disc, of a small size, at a place very distant from us. Does that silver disc exist at that place? With what suppositions does the assumption that it does conflict? Only, so far as I can see, with the supposition that the place in question is really occupied by a body such as science has taught us to suppose that the moon really is—a spherical body immensely larger than objects, in comparison with which the silver disc which we perceive is small; or else with the supposition that the place in question is really occupied by some part of our atmosphere, or some part of the medium which science supposes to exist between our atmosphere and the moon; or else with the supposition that the place in question is really occupied by what we might see, if the moon were nearer to us by many thousands of miles. Unless we suppose that some other object is in the place, in which the silver disc appears to be, and that this object is of a kind which cannot occupy the same place which is occupied by a silver disc, we have no reason to suppose that the silver disc does not really exist in the place where it appears to be. And, in this case, we perhaps have reason for both suppositions and should therefore conclude that the silver disc, which we perceive, does not exist in any real place.

Part, therefore, of these objections to our theory may, I think, be met by admitting that some of the ... sensible qualities which we perceive do not exist at the places where they appear to exist, though ethers do. But there is, I think, another class of cases, in which we may be justified in denying that two things which (it is asserted) cannot occupy the same space, really cannot. I will take an instance which is, I think, typical. When we look at a drop of blood with the naked eye, we perceive a small red spot, uniformly red all over. But when (as we say) we look at the same object under a microscope of a certain power, I am informed that we see a much larger spot, of similar shape, indeed, but not uniformly red—having, in fact, small red spots at different positions in a yellowish field. And if we were again to look at the same object through a microscope of much higher power still, we might perceive yet a third different arrangement of colours. Is there any fatal objection to supposing that all three appearances—the uniform red spot, the yellowish field with reddish spots in it, and the third, whatever that may be—do all really occupy the same real spatial area? I cannot see that there is. We are familiar with the idea that a given spatial area may contain parts which are invisible to us. And hence, I think it is quite conceivable that parts of a given area may be really occupied by one colour, while the whole is really occupied by another. And this, I think, is what we actually do believe in many cases. At all events, we certainly believe that the area which appears to be occupied by one colour really is the same area as that which appears to be occupied by another. And, unless we assume that the area, in both cases, really is the same, we can certainly have no reason to deny that each colour does really occupy the area which it appears to occupy.

For these reasons I think that the difficulties in the way of supposing that some of the sensible qualities which we perceive as being in certain places, really exist in the places in which we perceive them to be, are not insuperable. I have indeed not done justice to these difficulties; but then, neither have I done justice to what is to be said on the other side. At all events, I think it is plain that we have no reason to assert, in any case whatever, that a perceived colour does not really exist in the place where it is perceived as being, unless we assume that that very same place really is occupied by something else—either by some different sensible qualities or by material objects such as physical science supposes to exist. But what reason can we give for such an assumption? I have tried to show that our own observations can give us none, unless we assume that some of the sensible qualities, which we observe as occupying certain places, do really exist in those places. And, if this is so, then we must admit that neither he who believes (with Reid) in the existence of other minds and of matter also, nor he who believes in the existence of other minds and denies that of matter, can have, in his own observations, the slightest reason either for his assertion or for his denial: we must admit that he can have no reason for either assertion or denial, except one which consists in the assumption of the existence or nonexistence of something which he does not observe—something, therefore, of the very same kind as that for which he gives it as a reason. I am very unwilling to suppose that this is the case: I am very unwilling to suppose that he who believes that Sindbad the Sailor really saw what the "Arabian Nights" represent him as seeing, has just as good reason (so far as his own observation goes) for believing this as he who denies it has for denying it. Still this may be the case. We must, perhaps, be content to assume as certain that for which our observation gives no reason: to assume such propositions as that Sindbad did not see a Roc, and that you do hear my voice. But if it is said that these things are certain; then it also appears to me to be certain that the colours which I perceive do exist (some of them) where I perceive them. The more I look at objects round me, the more I am unable to resist the conviction that what I see does exist, as truly and as really, as my perception of it The conviction is overwhelming.

This being, then, the state of the case, I think I may at least plead that we have grounds for suspense of judgment as to whether what I see does not really exist; grounds, too, for renewed enquiry, more careful than such enquiry has sometimes been in the past.

[1] Not now in 1921.

[WILLIAM JAMES]

My object in this paper is to discuss some of the things which Prof. William James says about truth in the recent book, to which he has given the above name.[1] In Lecture VI he professes to give an account of a theory, which he calls "the pragmatist theory of truth;" and he professes to give a briefer preliminary account of the same theory in Lecture II. Moreover, in Lecture VII, he goes on to make some further remarks about truth. In all these Lectures he seems to me to make statements to which there are very obvious objections; and my main object is to point out, as clearly and simply as I can, what seem to me to be the principal objections to some of these statements.

We may, I think, distinguish three different things which he seems particularly anxious to assert about truth.

(I) In the first place, he is plainly anxious to assert some connection between truth and "verification" or "utility." Our true ideas, he seems to say, are those that "work," in the sense that they are or can be "verified," or are "useful."

(II) In the second place, he seems to object to the view that truth is something "static" or "immutable." He is anxious to assert that truths are in some sense "mutable."

(III) In the third place, he asserts that "to an unascertainable extent our truths are man-made products" (p. 242).

To what he asserts under each of these three heads there are, I think, serious objections; and I now propose to point out what seem to me to be the principal ones, under each head separately.

(I)

Professor James is plainly anxious to assert some connection between truth and "verification" or "utility." And that there is some connection between them everybody will admit. That many of our true ideas are verified; that many of them can be verified; and that many of them are useful, is, I take it, quite indisputable. But Professor James seems plainly to wish to assert something more than this. And one more thing which he wishes to assert is, I think, pretty plain. He suggests, at the beginning of Lecture VI, that he is going to tell us in what sense it is that our true ideas "agree with reality." Truth, he says, certainly means their agreement with reality; the only question is as to what we are to understand by the words "agreement" and "reality" in this proposition. And he first briefly considers the theory, that the sense in which our true ideas agree with reality, is that they "copy" some reality. And he affirms that some of our true ideas really do do this. But he rejects the theory, as a theory of what truth means, on the ground that they do not all do so. Plainly, therefore, he implies that no theory of what truth means will be correct, unless it tells us of some property which belongs to all our true ideas without exception. But his own theory is a theory of what truth means. Apparently, therefore, he wishes to assert that not only many but all our true ideas are or can be verified; that all of them are useful. And it is, I think, pretty plain that this is one of the things which he wishes to assert.

Apparently, therefore, Professor James wishes to assert that all our true ideas are or can be verified—that all are useful. And certainly this is not a truism like the proposition that many of them are so. Even if this were all that he meant, it would be worth discussing. But even this, I think, is not all. The very first proposition in which he expresses his theory is the following. "True ideas," he says (p. 201) "are those that we can assimilate, validate, corroborate and verify. False ideas are those that we cannot." And what does this mean? Let us, for brevity's sake, substitute the word "verify" alone for the four words which Professor James uses, as he himself subsequently seems to do. He asserts, then, that true ideas are those which we can verify. And plainly he does not mean by this merely that some of the ideas which we can verify are true, while plenty of others, which we can verify, are not true. The plain meaning of his words is that all the ideas which we can verify are true. No one would use them who did not mean this. Apparently, therefore, Professor James means to assert not merely that we can verify all our true ideas; but also that all the ideas, which we can verify, are true. And so, too, with utility or usefulness. He seems to mean not merely that all our true ideas are useful; but that all those which are useful are true. This would follow, for one thing, from the fact that he seems to use the words "verification" or "verifiability" and "usefulness" as if they came to the same thing. But, in this case too, he asserts it in words that have but one plain meaning. "The true" he says (p. 222) "is only the expedient in the way of our thinking." "The true" is the expedient: that is, all expedient thinking is true. Or again: "An idea is 'true' so long as to believe it is profitable to our lives" (p. 75). That is to say, every idea, which is profitable to our lives, is, while it is so, true. These words certainly have a plain enough meaning. Apparently, therefore, Professor James means to assert not merely that all true ideas are useful, but also that all useful ideas are true.

Professor James' words, then, do at least suggest that he wishes to assert all four of the following propositions. He wishes to assert, it would seem—

(1) That we can verify all those of our ideas, which are true.

(2) That all those among our ideas, which we can verify, are true.

(3) That all our true ideas are useful.

(4) That all those of our ideas, which are useful, are true.

These four propositions are what I propose first to consider. He does mean to assert them, at least. Very likely he wishes to assert something more even than these. He does, in fact, suggest that he means to assert, in addition, that these properties of "verifiability" and "utility" are the only properties (beside that of being properly called "true") which belong to all our true ideas and to none but true ideas. But this obviously cannot be true, unless all these four propositions are true. And therefore we may as well consider them first.

First, then, can we verify all our true ideas?

I wish only to point out the plainest and most obvious reasons why I think it is doubtful whether we can.

We are very often in doubt as to whether we did or did not do a certain thing in the past. We may have the idea that we did, and also the idea that we did not; and we may wish to find out which idea is the true one. Very often, indeed, I may believe very strongly, that I did do a certain thing; and somebody else, who has equally good reason to know, may believe equally strongly that I did not. For instance, I may have written a letter, and may believe that I used certain words in it. But my correspondent may believe that I did not. Can we always verify either of these ideas? Certainly sometimes we can. The letter may be produced, and prove that I did use the words in question. And I shall then have verified my idea. Or it may prove that I did not use them. And then we shall have verified my correspondent's idea. But, suppose the letter has been destroyed; suppose there is no copy of it, nor any trustworthy record of what was said in it; suppose there is no other witness as to what I said in it, beside myself and my correspondent? Can we then always verify which of our ideas is the true one? I think it is very doubtful whether we can nearly always. Certainly we may often try to discover any possible means of verification, and be quite unable, for a time at least, to discover any. Such cases, in which we are unable, for a time at least, to verify either of two contradictory ideas, occur very commonly indeed. Let us take an even more trivial instance than the last. Bad whist-players often do not notice at all carefully which cards they have among the lower cards in a suit. At the end of a hand they cannot be certain whether they had or had not the seven of diamonds, or the five of spades. And, after the cards have been shuffled, a dispute will sometimes arise as to whether a particular player had the seven of diamonds or not. His partner may think that he had, and he himself may think that he had not. Both may be uncertain, and the memory of both, on such a point, may be well known to be untrustworthy. And, moreover, neither of the other players may be able to remember any better. Is it always possible to verify which of these ideas is the true one? Either the player did or did not have the seven of diamonds. This much is certain. One person thinks that he did, and another thinks he did not; and both, so soon as the question is raised, have before their minds both of these ideas—the idea that he did, and the idea that he did not. This also is certain. And it is certain that one or other of these two ideas is true. But can they always verify either of them? Sometimes, no doubt, they can, even after the cards have been shuffled. There may have been a fifth person present, overlooking the play, whose memory is perfectly trustworthy, and whose word may be taken as settling the point. Or the players may themselves be able, by recalling other incidents of play, to arrive at such a certainty as may be said to verify the one hypothesis or the other. But very often neither of these two things will occur. And, in such a case, is it always possible to verify the true idea? Perhaps, theoretically, it may be still possible. Theoretically, I suppose, the fact that one player, and not any of the other three, had the card in his hand, may have made some difference to the card, which might be discovered by some possible method of scientific investigation. Perhaps some such difference may remain even after the same card has been repeatedly used in many subsequent games. But suppose the same question arises again, a week after the original game was played. Did you, or did you not, last week have the seven of diamonds in that particular hand? The question has not been settled in the meantime; and now, perhaps, the original pack of cards has been destroyed. Is it still possible to verify either idea? Theoretically, I suppose, it may be still possible. But even this, I think, is very doubtful. And surely it is plain that, humanly and practically speaking, it will often have become quite impossible to verify either idea. In all probability it never will be possible for any man to verify whether I had the card or not on this particular occasion. No doubt we are here speaking of an idea, which some man could have verified at one time. But the hypothesis I am considering is the hypothesis that we never have a true idea, which we can not verify; that is to say, which we cannot verify after the idea has occurred. And with regard to this hypothesis, it seems to me quite plain that very often indeed we have two ideas, one or other of which is certainly true; and yet that, in all probability, it is no longer possible and never will be possible for any man to verify either.

It seems to me, then, that we very often have true ideas which we cannot verify; true ideas, which, in all probability, no man ever will be able to verify. And, so far, I have given only comparatively trivial instances. But it is plain that, in the same sense, historians are very frequently occupied with true ideas, which it is doubtful whether they can verify. One historian thinks that a certain event took place, and another that it did not; and both may admit that they cannot verify their idea. Subsequent historians may, no doubt, sometimes be able to verify one or the other. New evidence may be discovered or men may learn to make a better use of evidence already in existence. But is it certain that this will always happen? Is it certain that every question, about which historians have doubted, will some day be able to be settled by verification of one or the other hypothesis? Surely the probability is that in the case of an immense number of events, with regard to which we should like to know whether they happened or not, it never will be possible for any man to verify either the one hypothesis or the other. Yet it may be certain that either the events in question did happen or did not. Here, therefore, again, we have a large number of ideas—cases where many men doubt whether a thing did happen or did not, and have therefore the idea both of its having happened and of its not having happened—with regard to which it is certain that half of them are true, but where it seems highly doubtful whether any single one of them will ever be able to be verified. No doubt it is just possible that men will some day be able to verify every one of them. But surely it is very doubtful whether they will. And the theory against which I am protesting is the positive assertion that we can verify all our true ideas—that some one some day certainly will be able to verify every one of them. This theory, I urge, has all probability against it.

And so far I have been dealing only with ideas with regard to what happened in the past. These seem to me to be the cases which offer the most numerous and most certain exceptions to the rule that we can verify our true ideas. With regard to particular past events, either in their own lives or in those of other people, men very frequently have ideas, which it seems highly improbable that any man will ever be able to verify. And yet it is certain that a great many of these ideas are true, because in a great many cases we have both the idea that the event did happen and also the idea that it did not, when it is certain that one or other of these ideas is true. And these ideas with regard to past events would by themselves be sufficient for my purpose. If, as seems certain, there are many true ideas with regard to the past, which it is highly improbable that anyone will ever be able to verify, then, obviously, there is nothing in a true idea which makes it certain that we can verify it. But it is, I think, certainly not only in the case of ideas, with regard to the past, that it is doubtful whether we can verify all the true ideas we have. In the case of many generalisations dealing not only with the past but with the future, it is, I think, obviously doubtful whether we shall ever be able to verify all those which are true; although here, perhaps, in most cases, the probability that we shall not is not so great. But is it quite certain, that in all cases where scientific men have considered hypotheses, one or other of which must be true, either will ever be verified? It seems to be obviously doubtful. Take, for instance, the question whether our actual space is Euclidean or not. This is a case where the alternative has been considered; and where it is certain that, whatever be meant by "our actual space," it either is Euclidean or is not. It has been held, too, that the hypothesis that it is not Euclidean might, conceivably, be verified by observations. But it is doubtful whether it ever will be. And though it would be rash to say that no man ever will be able to verify either hypothesis; it is also rash to assert positively that we shall—that we certainly can verify the true hypotheses. There are, I believe, ever so many similar cases, where alternative hypotheses, one or other of which must be true, have occurred to men of science, and where yet it is very doubtful whether either ever will be verified. Or take, again, such ideas as the idea that there is a God, or the idea that we are immortal. Many men have had not only contradictory ideas, but contradictory beliefs, about these matters. And here we have cases where it is disputed whether these ideas have not actually been verified. But it seems to me doubtful whether they have been. And there is a view, which seems to me to deserve respect, that, in these matters, we never shall be able to verify the true hypothesis. Is it perfectly certain that this view is a false one? I do not say that it is true. I think it is quite possible that we shall some day be able to verify either the belief that we are immortal or the belief that we are not. But it seems to me doubtful whether we shall. And for this reason alone I should refuse to assent to the positive assertion that we certainly can verify all our true ideas.

When, therefore, Professor James tells us that "True ideas are those that we can assimilate, validate, corroborate and verify. False ideas are those that we cannot," there seems to be a serious objection to part of what these words imply. They imply that no idea of ours is true, unless we can verify it. They imply, therefore, that whenever a man wonders whether or not he had the seven of diamonds in the third hand at whist last night, neither of these ideas is true unless he can verify it. But it seems certain that in this, and an immense number of similar cases, one or other of the two ideas is true. Either, he did have the card in his hand or he did not. If anything is a fact, this is one. Either, therefore, Professor James' words imply the denial of this obvious fact, or else he implies that in all such cases we can verify one or other of the two ideas. But to this the objection is that, in any obvious sense of the words, it seems very doubtful whether we can. On the contrary it seems extremely probable that in a very large number of such cases no man ever will be able to verify either of the two ideas. There is, therefore, a serious objection to what Professor James' words imply. Whether he himself really means to assert these things which his words imply I do not know. Perhaps he would admit that, in this sense, we probably cannot verify nearly all our true ideas. All that I have wished to make plain is that there is, at least, an objection to what he says, whether to what he means or not. There is ample reason why we should refuse assent to the statement that none of our ideas are true, except those which we can verify.

But to another part of what he implies by the words quoted above, there is, I think, no serious objection. There is reason to object to the statement that we can verify all our true ideas; but to the statement that all ideas, which we can "assimilate, validate, corroborate and verify," are true, I see no serious objection. Here, I think, we might say simply that all ideas which we can verify are true. To this, which is the second of the four propositions, which I distinguished above ([p. 35]) as what Professor James seems to wish to assert, there is, I think, no serious objection, if we understand the word "verify" in its proper and natural sense. We may, no doubt, sometimes say that we have verified an idea or an hypothesis, when we have only obtained evidence which proves it to be probable, and does not prove it to be certain. And, if we use the word in this loose sense for incomplete verification, it is obviously the case that we may verify an idea which is not true. But it seems scarcely necessary to point this out. And where we really can completely verify an idea or an hypothesis, there, undoubtedly, the idea which we can verify is always true. The very meaning of the word "verify" is to find evidence which does really prove an idea to be true; and where an idea can be really proved to be true, it is of course, always true.

This is all I wish to say about Professor James' first two propositions, namely:—

(1) That no ideas of ours are true, except those which we can verify.

(2) That all those ideas, which we can verify, are true.

The first seems to me extremely doubtful—in fact, almost certainly untrue; the second on the other hand, certainly true, in its most obvious meaning. And I shall say no more about them. The fact is, I doubt whether either of them expresses anything which Professor James is really anxious to assert. I have mentioned them, only because his words do, in fact, imply them and because he gives those words a very prominent place. But I have already had occasion to notice that he seems to speak as if to say that we can verify an idea came to the same thing as saying it is useful to us. And it is the connection of truth with usefulness, not its connection with "verification," that he is, I think, really anxious to assert. He talks about "verification" only, I believe, because he thinks that what he says about it will support his main view that truth is what "works," is "useful," is "expedient," "pays." It is this main view we have now to consider. We have to consider the two propositions:—

(3) That all our true ideas are useful.

(4) That all ideas, which are useful, are true.

First, then: is it the case that all our true ideas are useful? Is it the case that none of our ideas are true, except those which are useful?

I wish to introduce my discussion of this question by quoting a passage in which Professor James seems to me to say something which is indisputably true. Towards the end of Lecture VI, he attacks the view that truths "have an unconditional claim to be recognised." And in the course of his attack the following passage occurs:—

"Must I," he says, "constantly be repeating the truth 'twice two are four' because of its eternal claim on recognition? or is it sometimes irrelevant? Must my thoughts dwell night and day on my personal sins and blemishes, because I truly have them?—or may I sink and ignore them in order to be a decent social unit, and not a mass of morbid melancholy and apology?"

"It is quite evident," he goes on, "that our obligation to acknowledge truth, so far from being unconditional, is tremendously conditional. Truth with a big T, and in the singular, claims abstractly to be recognised, of course; but concrete truths in the plural need be recognised only when their recognition is expedient." (pp. 231-232).

What Professor James says in this passage seems to me so indisputably true as fully to justify the vigour of his language. It is as clear as anything can be that it would not be useful for any man's mind to be always occupied with the true idea that he had certain faults and blemishes; or to be always occupied with the idea that twice two are four. It is clear, that is, that, if there are times at which a particular true idea is useful, there certainly are other times at which it would not be useful, but positively in the way. This is plainly true of nearly all, if not quite all, our true ideas. It is plainly true with regard to nearly all of them that, even if the occasions on which their occurrence is useful are many, the occasions on which their occurrence would not be useful are many more. With regard to most of them it is true that on most occasions they will, as Professor James says elsewhere, "be practically irrelevant, and had better remain latent."

It is, then, quite clear that almost any particular true idea would not be useful at all times and that the times at which it would not be useful, are many more than the times at which it would. And what we have to consider is whether, in just this sense in which it is so clear that most true ideas would not be useful at most times, it is nevertheless true that all our true ideas are useful. Is this so? Are all our true ideas useful?

Professor James, we see, has just told us that there are ever so many occasions upon which a particular true idea, such as that 2 + 2= 4, would not be useful—when, on the contrary, it would be positively in the way. And this seems to be indisputably clear. But is not something else almost equally clear? Is it not almost equally clear that cases, such as he says would not be useful, do sometimes actually happen? Is it not clear that we do actually sometimes have true ideas, at times when they are not useful, but are positively in the way? It seems to me to be perfectly clear that this does sometimes occur; and not sometimes only, but very commonly. The cases in which true ideas occur at times when they are useful, are, perhaps, far more numerous; but, if we look at men in general, the cases in which true ideas occur, at times when they are not useful, do surely make up positively a very large number. Is it not the case that men do sometimes dwell on their faults and blemishes, when it is not useful for them to do so? when they would much better be thinking of something else? Is it not the case that they are often unable to get their minds away from a true idea, when it is harmful for them to dwell on it? Still more commonly, does it not happen that they waste their time in acquiring pieces of information which are no use to them, though perhaps very useful to other people? All this seems to me to be undeniable—just as undeniable as what Professor James himself has said; and, if this is so, then, in one sense of the words, it is plainly not true that all, or nearly all, our true ideas are useful. In one sense of the words. For if I have the idea that 2+2=4 on one day, and then have it again the next, I may certainly, in a sense, call the idea I have on one day one idea, and the idea I have on the next another. I have had two ideas that 2+2=4, and not one only. Or if two different persons both think that I have faults, there have been two ideas of this truth and not one only. And in asking whether all our true ideas are useful, we might mean to ask whether both of these ideas were useful and not merely whether one of them was. In this sense, then, it is plainly not true that all our true ideas are useful. It is not true, that is, that every true idea is useful, whenever it occurs.

In one sense, then, it is plainly not true that all our true ideas are useful. But there still remains a perfectly legitimate sense in which it might be true. It might be meant, that is, not that every occurrence of a true idea is useful, but that every true idea is useful on at least one of the occasions when it occurs. But is this, in fact, the case? It seems to me almost as plain that it is not, as that the other was not. We have seen that true ideas are not by any means always useful on every occasion when they occur; though most that do occur many times over and to many different people are, no doubt, useful on some of these occasions. But there seems to be an immense number of true ideas, which occur but once and to one person, and never again either to him or to anyone else. I may, for instance, idly count the number of dots on the back of a card, and arrive at a true idea of their number; and yet, perhaps, I may never think of their number again, nor anybody else ever know it. We are all, it seems to me, constantly noticing trivial details, and getting true ideas about them, of which we never think again, and which nobody else ever gets. And is it quite certain that all these true ideas are useful? It seems to me perfectly clear, on the contrary, that many of them are not. Just as it is clear that many men sometimes waste their time in acquiring information which is useful to others but not to them, surely it is clear that they sometimes waste their time in acquiring information, which is useful to nobody at all, because nobody else ever acquires it. I do not say that it is never useful idly to count the number of dots on the back of a card. Plainly it is sometimes useful to be idle, and one idle employment may often be as good as another. But surely it is true that men sometimes do these things when their time would have been better employed otherwise? Surely they sometimes get into the habit of attending to trivial truths, which it is as great a disadvantage that they should attend to as that they should constantly be thinking of their own thoughts and blemishes? I cannot see my way to deny that this is so; and therefore I cannot see my way to assert positively that all our true ideas are useful, even so much as on one occasion. It seems to me that there are many true ideas which occur but once, and which are not useful when they do occur. And if this be so, then it is plainly not true that all our true ideas are useful in any sense at all.

These seem to me to be the most obvious objections to the assertion that all our true ideas are useful. It is clear, we saw to begin with, that true ideas, which are sometimes useful, would not be useful at all times. And it seemed almost equally clear that they do sometimes occur at times when they are not useful. Our true ideas, therefore are not useful at every time when they actually occur. But in just this sense in which it is so clear that true ideas which are sometimes useful, nevertheless sometimes occur at times when they are not, it seems pretty plain that true ideas, which occur but once, are, some of them, not useful. If an idea, which is sometimes useful, does sometimes occur to a man at a time when it is irrelevant and in the way, why should not an idea, which occurs but once, occur at a time when it is irrelevant and in the way? It seems hardly possible to doubt that this does sometimes happen. But, if this be so, then it is not true that all our true ideas are useful, even so much as on one occasion. It is not true that none of our ideas are true, except those which are useful.

But now, what are we to say of the converse proposition—the proposition that all those among our ideas, which are useful, are true? That we never have a useful idea, which is not true?

I confess the matter seems to me equally clear here. The assertion should mean that every idea, which is at any time useful, is true; that no idea, which is not true, is ever useful. And it seems hardly possible to doubt that this assertion is false. It Is, in the first place, commonly held that it is sometimes right positively to deceive another person. In war, for instance it is held that one army is justified in trying to give the enemy a false idea as to where it will be at a given time. Such a false idea is sometimes given, and it seems to me quite clear that it is sometimes useful. In such a case, no doubt, it may be said that the false idea is useful to the party who have given it, but not useful to those who actually believe in it. And the question whether it is useful on the whole will depend upon the question which side it is desirable should win. But it seems to me unquestionable that the false idea is sometimes useful on the whole. Take, for instance, the case of a party of savages, who wish to make a night attack and massacre a party of Europeans but are deceived as to the position in which the Europeans are encamped. It is surely plain that such a false idea is sometimes useful on the whole. But quite apart from the question whether deception is ever justifiable, it is not very difficult to think of cases where a false idea, not produced by deception, is plainly useful—and useful, not merely on the whole, but to the person who has it as well. A man often thinks that his watch is right, when, in fact, it is slow, and his false idea may cause him to miss his train. And in such cases, no doubt, his false idea is generally disadvantageous. But, in a particular case, the train which he would have caught but for his false idea may be destroyed in a railway accident, or something may suddenly occur at home, which renders it much more useful that he should be there, than it would have been for him to catch his train. Do such cases never occur? And is not the false idea sometimes useful in some of them? It seems to me perfectly clear that it is sometimes useful for a man to think his watch is right when it is wrong. And such instances would be sufficient to show that it is not the case that every idea of ours, which is ever useful, is a true idea. But let us take cases, not, like these, of an idea, which occurs but a few times or to one man, but of ideas which have occurred to many men at many times. It seems to me very difficult to be sure that the belief in an eternal hell has not been often useful to many men, and yet it may be doubted whether this idea is true. And so, too, with the belief in a happy life after death, or the belief in the existence of a God; it is, I think, very difficult to be sure that these beliefs have not been, and are not still, often useful, and yet it may be doubted whether they are true. These beliefs, of course, are matters of controversy. Some men believe that they are both useful and true; and others, again, that they are neither. And I do not think we are justified in giving them as certain instances of beliefs, which are not true, but, nevertheless, have often been useful. But there is a view that these beliefs, though not true, have, nevertheless, been often useful; and this view seems to me to deserve respect, especially since, as we have seen, some beliefs, which are not true, certainly are sometimes useful. Are we justified in asserting positively that it is false? Is it perfectly certain that beliefs, which have often been useful to many men, may not, nevertheless, be untrue? Is it perfectly certain that beliefs, which are not true, have not often been useful to many men? The certainty may at least be doubted, and in any case it seems certain that some beliefs, which are not true, are, nevertheless, sometimes useful.

For these reasons, it seems to me almost certain that both the assertions which I have been considering are false. It is almost certainly false that all our true ideas are useful, and almost certainly false that all our useful ideas are true. But I have only urged what seem to me to be the most obvious objections to these two statements; I have not tried to sustain these objections by elaborate arguments, and I have omitted elaborate argument, partly because of a reason which I now wish to state. The fact is, I am not at all sure that Professor James would not himself admit that both these statements are false. I think it is quite possible he would admit that they are, and would say that he never meant either to assert or to imply the contrary. He complains that some of the critics of Pragmatism are unwilling to read any but the silliest of possible meanings into the statements of Pragmatism; and, perhaps, he would say that this is the case here. I certainly hope that he would. I certainly hope he would say that these statements, to which I have objected, are silly. For it does seem to me intensely silly to say that we can verify all our true ideas; intensely silly to say that every one of our true ideas is at some time useful; intensely silly to say that every idea which is ever useful is true. I hope Professor James would admit all these things to be silly, for if he and other Pragmatists would admit even as much as this, I think a good deal would be gained. But it by no means follows that because a philosopher would admit a view to be silly, when it is definitely put before him, he has not himself been constantly holding and implying that very view. He may quite sincerely protest that he never has either held or implied it, and yet he may all the time have been not only implying it but holding it—vaguely, perhaps, but really. A man may assure us, quite sincerely that he is not angry; he may really think that he is not, and yet we may be able to judge quite certainly from what he says that he really is angry. He may assure us quite sincerely that he never meant anything to our discredit by what he said—that he was not thinking of anything in the least discreditable to us, and yet it may be plain from his words that he was actually condemning us very severely. And so with a philosopher. He may protest, quite angrily, when a view is put before him in other words than his own, that he never either meant or implied any such thing, and yet it may be possible to judge, from what he says, that this very view, wrapped up in other words, was not only held by him but was precisely what made his thoughts seem to him to be interesting and important. Certainly he may quite often imply a given thing which, at another time, he denies. Unless it were possible for a philosopher to do this, there would be very little inconsistency in philosophy, and surely everyone will admit that other philosophers are very often inconsistent. And so in this case, even if Professor James would say that he never meant to imply the things to which I have been objecting, yet in the case of two of these things, I cannot help thinking that he does actually imply them—nay more, that he is frequently actually vaguely thinking of them, and that his theory of truth owes its interest, in very great part, to the fact that he is implying them. In the case of the two views that all our true ideas are useful, and that all our useful ideas are true, I think this is so, and I do not mean merely that his words imply them. A man's words may often imply a thing, when he himself is in no way, however vaguely, thinking either of that thing or of anything which implies it; he may simply have expressed himself unfortunately. But in the case of the two views that all our true ideas are useful, and all our useful ideas true, I do not think this is so with Professor James. I think that his thoughts seem interesting to him and others, largely because he is thinking, not merely of words, but of things which imply these two views, in the very form in which I have objected to them. And I wish now to give some reasons for thinking this.

Professor James certainly wishes to assert that there is some connection between truth and utility. And the connection which I have suggested that he has vaguely before his mind is this: that every true idea is, at some time or other, useful, and conversely that every idea, which is ever useful, is true. And I have urged that-there are obvious objections to both these views. But now, supposing Professor James does not mean to assert either of these two things, what else can he mean to assert? What else can he mean, that would account for the interest and importance he seems to attach to his assertion of connection between truth and utility? Let us consider the alternatives.

And, first of all, he might mean that most of our true ideas are useful, and most of our useful ideas true. He might mean that most of our true ideas are useful at some time or other; and even that most of them are useful, whenever they actually occur. And he might mean, moreover, that if we consider the whole range of ideas, which are useful to us, we shall find that by far the greater number of them are true ones; that true ideas are far more often useful to us, than those which are not true. And all this, I think, may be readily admitted to be true. If this were all that he meant, I do not think that anyone would be very anxious to dispute it. But is it conceivable that this is all that he means? Is it conceivable that he should have been so anxious to insist upon this admitted commonplace? Is it conceivable that he should have been offering us this, and nothing more, as a theory of what truth means, and a theory worth making a fuss about, and being proud of? It seems to me quite inconceivable that this should have been all that he meant. He must have had something more than this in his mind. But, if so, what more?

In the passage which I quoted at the beginning, as showing that he does mean to assert that all useful ideas are true, he immediately goes on to assert a qualification, which must now be noticed. "The true," he says, "is only the expedient in the way of our thinking" (p. 222). But he immediately adds: "Expedient in the long run, and on the whole, of course; for what meets expediently all the experience in sight won't necessarily meet all further experiences equally satisfactorily." Here, therefore, we have something else that he might mean. What is expedient in the long run, he means to say, is true. And what exactly does this mean? It seems to mean that an idea, which is not true, may be expedient for some time. That is to say, it may occur once, and be expedient then; and again, and be expedient then; and so on, over a considerable period. But (Professor James seems to prophesy) if it is not true, there will come a time, when it will cease to be expedient. If it occurs again and again over a long enough period, there will at last, if it is not true, come a time when it will (for once at least) fail to be useful, and will (perhaps he means) never be useful again. This is, 1 think, what Professor James means in this passage. He means, I think, that though an idea, which is not true, may for some time be repeatedly expedient, there will at last come a time when its occurrence will, perhaps, never be expedient again, certainly will, for a time, not be generally expedient. And this a view which, it seems to me, may possibly be true. It is certainly possible that a time may come, in the far future, when ideas, which are not true, will hardly ever, if ever, be expedient. And this is all that Professor James seems here positively to mean. He seems to mean that, if you take time enough, false ideas will some day cease to be expedient. And it is very difficult to be sure that this is not true; since it is very difficult to prophesy as to what may happen in the far future. I am sure I hope that this prophesy will come true. But in the meantime (Professor James seems to admit) ideas, which are not true, may, for an indefinitely long time, again and again be expedient. And is it conceivable that a theory, which admits this, is all that he has meant to assert? Is it conceivable that what interests him, in his theory of truth, is merely the belief that, some day or other, false ideas will cease to be expedient? "In the long run, of course," he says, as if this were what he had meant all along. But I think it is quite plain that this is not all that he has meant. This may be one thing which he is anxious to assert, but it certainly does not explain the whole of his interest in his theory of truth.

And, in fact, there is quite a different theory which he seems plainly to have in his mind in other places. When Professor James says, "in the long run, of course," he implies that ideas which are expedient only for a short run, are very often not true. But in what he says elsewhere he asserts the very opposite of this. He says elsewhere that a belief is true "so long as to believe it is profitable to our lives" (p. 75). That is to say, a belief will be true, so long as it is useful, even if it is not useful in the long run! This is certainly quite a different theory; and, strictly speaking, it implies that an idea, which is useful even on one occasion, will be true. But perhaps this is only a verbal implication. I think very likely that here Professor James was only thinking of ideas, which can be said to have a run, though only a comparatively short one—of ideas, that is, which are expedient, not merely on one occasion, but for some time. That is to say, the theory which he now suggests, is that ideas, which occur again and again, perhaps to one man only, perhaps to several different people, over some space of time are, if they are expedient on most occasions within that space of time, true. This is a view which he is, I think, really anxious to assert; and if it were true, it would, I think, be important. And it is difficult to find instances which show, with certainty, that it is false. I believe that it is false; but it is difficult to prove it, because, in the case of some ideas it is so difficult to be certain that they ever were useful, and in the case of others so difficult to be certain that they are not true. A belief such as I spoke of before—the belief in eternal hell—is an instance. I think this belief has been, for a long time, useful, and that yet it is false. But it is, perhaps, arguable that it never has been useful; and many people on the other hand, would still assert that it is true. It cannot, therefore, perhaps, fairly be used as an instance of a belief, which is certainly not true, and yet has for some time been useful. But whether this view that all beliefs, which are expedient for some time, are true, be true or false; can it be all that Professor James means to assert? Can it constitute the whole of what interests him in his theory of truth?

I do not think it can. I think it is plain that he has in his mind something more than any of these alternatives, or than all of them taken together. And I think so partly for the following reason. He speaks from the outset as if he intended to tell us what distinguishes true ideas from those which are not true; to tell us, that is to say, not merely of some property which belongs to all our true ideas; nor yet merely of some property, which belongs to none but true ideas; but of some property which satisfies both these requirements at once—which both belongs to all our true ideas, and also belongs to none but true ones. Truth, he says to begin with, means the agreement of our ideas with reality; and he adds "as falsity their disagreement." And he explains that he is going to tell us what property it is that is meant by these words "agreement with reality." So again in the next passage which I quoted: "True ideas," he says "are those that we can assimilate, validate, corroborate and verify." But, he also adds, "False ideas are those that we cannot." And no one, I think, could possibly speak in this way, who had not in his head the intention of telling us what property it is which distinguishes true ideas from those which are not true, and which, therefore, not only belongs to all ideas which are true, but also to none that are not. And that he has this idea in his head and thinks that the property of being "useful" or "paying" is such a property, is again clearly shown by a later passage. "Our account of truth," he says (p. 218) "is an account of truths in the plural, of processes of leading, realised in rebus, and having only this quality in common, that they pay." Only this quality in common! If this be so, the quality must obviously be one, which is not shared by any ideas which are not true; for, if true ideas have any quality in common at all, they must have at least one such quality, which is not shared by those which are not true. Plainly, therefore, Professor James is intending to tell us of a property which belongs both to all true ideas and only to true ideas. And this property, he says, is that of "paying." But now let us suppose that he means by "paying," not "paying once at least," but, according to the alternative he suggests, "paying in the long run" or "paying for some time." Can he possibly have supposed that these were properties which belonged both to all true ideas and also to none but true ones? They may, perhaps, be properties which belong to none but true ones. I doubt, as I have said, whether the latter does; but still it is difficult to prove the opposite. But even if we granted that they belong to none but true ones, surely it is only too obvious that they do not fulfil the other requirement—that they do not belong to nearly all true ones. Can anyone suppose that all our true ideas pay "in the long run" or repeatedly for some time? Surely it is plain that an enormous number do not for the simple reason that an enormous number of them have no run at all, either long or short, but occur but once, and never recur. I believe truly that a certain book is on a particular shelf about 10.15 p.m. on December 21st, 1907; and this true belief serves me well and helps me to find it But the belief that that book is there at that particular time occurs to no one else, and never again to me. Surely there are thousands of useful true beliefs which, like this, are useful but once, and never occur again; and it would, therefore, be preposterous to say that every true idea is useful "in the long run" or repeatedly for some time. If, therefore, we supposed Professor James to mean that "paying in the long run" or "paying repeatedly over a considerable period" were properties which belonged to all true ideas and to none but true ones, we should be supposing him to mean something still more monstrous than if we suppose him to mean that "paying at least once" was such a property.

To sum up then:

I think there is no doubt that Professor James' interest in "the pragmatist theory of truth" is largely due to the fact that he thinks it tells us what distinguishes true ideas from those which are not true. And he thinks the distinction is that true ideas "pay," and false ones don't. The most natural interpretation of this view is: That every true idea pays at least once; and that every idea, which pays at least once, is true. These were the propositions I considered first, and I gave reasons for thinking that both are false. But Professor James suggested elsewhere that what he means by "paying" is "paying in the long run." And here it seems possibly true that all ideas which "pay in the long run" are true; but it is certainly false that all our true ideas "pay in the long run," if by this be meant anything more than "pay at least once." Again, he suggested that what he meant by paying was "paying for some time." And here, again, even if it is true (and it seems very doubtful) that all ideas which pay for some time are true, it is certainly false that all our true ideas pay for some time, if by this be meant anything more than that they pay "at least once."

This, I think, is the simplest and most obvious objection to Professor James' "instrumental" view of truth—the view that truth is what "works," "pays," is "useful." He seems certainly to have in his mind the idea that this theory tells us what distinguishes true ideas from false ones, and to be interested in it mainly for this reason. He has vaguely in his mind that he has told us of some property which belongs to all true ideas and to none but true ones; and that this property is that of "paying." And the objection is, that, whatever we understand by "paying," whether "paying at least once," or "paying in the long run," or "paying for some time," it seems certain that none of these properties will satisfy both requirements. As regards the first, that of "paying at least once," it seems almost certain that it satisfies neither: it is neither true that all our true ideas "pay at least once," nor yet that every idea which pays at least once, is true. On the contrary, many true ideas never pay at all; and many ideas, which are not true, do pay on at least one occasion. And as regards the others, "paying in the long run" and "paying for some time," even if these do belong to none but true ideas (and even this seems very doubtful), they certainly neither of them satisfy the other requirement—neither of them belong to all our true ideas. For, in order that either of them may belong to an idea, that idea must pay at least once; and, as we have seen, many true ideas do not pay even once, and cannot, therefore, pay either in the long run or for some time. And, moreover, many true ideas, which do pay on one occasion, seem to pay on one occasion and one only.

And, if Professor James does not mean to assert any of these things, what is there left for him to mean? There is left in the first place, the theory that most of our true ideas do pay; and that most of the ideas which pay are true. This seems to me to be true, and, indeed, to be all that is certainly true in what he says. But is it conceivable that this is all he has meant? Obviously, these assertions tell us of no property at all which belongs to all true ideas, and to none but true ones; and, moreover, it seems impossible that he should have been so anxious to assert this generally admitted commonplace. What a very different complexion his whole discussion would have worn, had he merely asserted this—this quite clearly, and nothing but this, while admitting openly that many true ideas do not pay, and that many, which do pay, are not true!

And, besides this commonplace, there is only left for him to mean two one-sided and doubtful assertions to the effect that certain properties belong to none but true ideas. There is the assertion that all ideas which pay in the long run are true, and the assertion that all ideas which pay for some considerable time are true. And as to the first, it may be true; but it may also be doubted, and Professor James gives us no reason at all for thinking that it is true. Assuming that religious ideas have been useful in the past, is it quite certain that they may not permanently continue to be useful, even though they are false? That, in short, even though they are not true, they nevertheless will be useful, not only for a time, but in the long run? And as for the assertion that all ideas, which pay for a considerable time, are true, this is obviously more doubtful still. Whether certain religious ideas will or will not be useful in the long run, it seems difficult to doubt that many of them have been useful for a considerable time. And why should we be told dogmatically that all of these are true? This, it seems to me, is by far the most interesting assertion, which is left for Professor James to make, when we have rejected the theory that the property of being useful belongs to all true ideas, as well as to none but true ones. But he has given no reason for asserting it. He seems, in fact, to base it merely upon the general untenable theory, that utility belongs to all true ideas, and to none but true ones; that this is what truth means.

These, then, seem to me the plainest and most obvious objections to what Professor James says about the connection between truth and utility. And there are only two further points, in what he says under this head, that I wish to notice.

In the first place, we have hitherto been considering only whether it is true, as a matter of empirical fact, that all our true ideas are useful, and those which are not true, never. Professor James seems, at least, to mean that, as a matter of fact, this is so; and I have only urged hitherto that as a matter of fact, it is not so. But as we have seen, he also asserts something more than this—he also asserts that this property of utility is the only one which belongs to all our true ideas. And this further assertion cannot possibly be true, if, as I have urged, there are many true ideas which do not possess this property; or if, as I have urged, many ideas, which do possess it, are nevertheless not true. The objections already considered are, then, sufficient to overthrow this further assertion also. If there are any true ideas, which are not useful, or if any, which are useful, are not true, it cannot be the case that utility is the only property which true ideas have in common. There must be some property, other than utility, which is common to all true ideas; and a correct theory as to what property it is that does belong to all true ideas, and to none but true ones, is still to seek. The empirical objections, hitherto given, are then sufficient objections to this further assertion also; but they are not the only objections to it. There is another and still more serious objection to the assertion that utility is the only property which all true ideas have in common. For this assertion does not merely imply that, as a matter of fact, all our true ideas and none but true ideas are useful. It does, indeed, imply this; and therefore the fact that these empirical assertions are not true is sufficient to refute it. But it also implies something more. If utility were the only property which all true ideas had in common, it would follow not merely that all true ideas are useful, but also that any idea, which was useful, would be true no matter what other properties it might have or might fail to have. There can, I think, be no doubt that Professor James does frequently speak as if this were the case; and there is an independent and still more serious objection to this implication. Even if it were true (as it is not) that all our true ideas and none but true ideas are, as a matter of fact, useful, we should still have a strong reason to object to the statement that any idea, which was useful, would be true. For it implies that if such an idea as mine, that Professor James exists, and has certain thoughts, were useful, this idea would be true, even if no such person as Professor James ever did exist. It implies that, if the idea that I had the seven of diamonds in my hand at cards last night, were useful, this idea would be true, even if, in fact, I did not have that card in my hand. And we can, I think, see quite plainly that this is not the case. With regard to some kinds of ideas, at all events—ideas with regard to the existence of other people, or with regard to past experiences of our own—it seems quite plain that they would not be true, unless they "agreed with reality" in some other sense than that which Professor James declares to be the only one in which true ideas must agree with it. Even if my idea that Professor James exists were to "agree with reality," in the sense that, owing to it, I handled other realities better than I should have done without it, it would, I think, plainly not be true, unless Professor James really did exist—unless he were a reality. And this, I think, is one of the two most serious objections to what he seems to hold about the connection of truth with utility. He seems to hold that any idea, which was useful, would be true, no matter what other properties it might fail to have. And with regard to some ideas, at all events, it seems plain that they cannot be true, unless they have the property that what they believe to exist, really does or did exist. Beliefs in the existence of other people might be useful to me, even if I alone existed; but, nevertheless, in such a case, they would not be true.

And there is only one other point, in what Professor James says in connection with the "instrumental" view of truth, upon which I wish to remark. We have seen that he seems sometimes to hold that beliefs are true, so long as they are "profitable to our lives." And this implies, as we have seen, the doubtful proposition than any belief which is useful for some length of time, is true. But this is not all that it implies. It also implies that beliefs are true only so long as they are profitable. Nor does Professor James appear to mean by this that they occur, only so long as they are profitable. He seems to hold, on the contrary, that beliefs, which are profitable for some time, do sometimes finally occur at a time when they are not profitable. He implies, therefore, that a belief, which occurs at several different times, may be true at some of the times at which it occurs, and yet untrue at others. I think there is no doubt that this view is what he is sometimes thinking of. And this, we see, constitutes a quite new view as to the connection between truth and utility—a view quite different from any that we have hitherto considered. This view asserts not that every true idea is useful at some time, or in the long run, or for a considerable period; but that the truth of an idea may come and go, as its utility comes and goes. It admits that one and the same idea sometimes occurs at times when it is useful, and sometimes at times when it is not; but it maintains that this same idea is true, at those times when it is useful, and not true, at those when it is not. And the fact that Professor James seems to suggest this view, constitutes, I think, a second most serious objection to what he says about the connection of truth and utility. It seems so obvious that utility is a property which comes and goes—which belongs to a given idea at one time, and does not belong to it at another, that anyone who says that the true is the useful naturally seems not to be overlooking this obvious fact, but to be suggesting that truth is a property which comes and goes in the same way. It is, in this way I think, that the "instrumental" view of truth is connected with the view that truth is "mutable." Professor James does, I think, imply that truth is mutable in just this sense—namely, that one and the same idea may be true at some of the times at which it occurs, and not true at others, and this is the view which I have next to consider.

(II)

Professor James seems to hold, generally, that "truth" is mutable. And by this he seems sometimes to mean that an idea which, when it occurs at one time, is true, may, when it occurs at another time, not be true. He seems to hold that one and the same idea may be true at one time and false at another. That it may be, for I do not suppose he means that all ideas do actually undergo this change from true to false. Many true ideas seem to occur but once, and, if so, they, at least, will not actually be true at one time and false at another, though, even with regard to these, perhaps Professor James means to maintain that they might be false at another time, if they were to occur at it. But I am not sure that he even means to maintain this with regard to all our true ideas. Perhaps he does not mean to say, with regard to all of them, even that they can change from true to false. He speaks, generally, indeed, as if truth were mutable; but, in one passage, he seems to insist that there is a certain class of true ideas, none of which are mutable in this respect. "Relations among purely mental ideas," he says (p. 209), "form another sphere where true and false beliefs obtain, and here the beliefs are absolute or unconditional. When they are true they bear the name either of definitions or of principles. It is either a principle or a definition that 1 and 1 make 2, that 2 and 1 make 3, and so on; that white differs less from grey than it does from black; that when the cause begins to act the effect also commences. Such propositions hold of all possible 'ones,' of all conceivable 'whites,' 'greys,' and 'causes.' The objects here are mental objects. Their relations are perceptually obvious at a glance, and no sense-verification is necessary. Moreover, once true, always true, of those same mental objects. Truth here has an 'eternal' character. If you can find a concrete thing anywhere that is 'one' or 'white' or 'grey' or an 'effect,' then your principles will everlastingly apply to it." Professor James does seem here to hold that there are true ideas, which once true, are always true. Perhaps, then, he does not hold that all true ideas are mutable. Perhaps he does not even hold that all true ideas, except ideas of this kind, are so. But he does seem to hold at least that many of our true ideas are mutable. And even this proposition seems to me to be disputable. It seems to me that there is a sense in which it is the case with every true idea that, if once true, it is always true. That is to say, that every idea, which is true once, would be true at any other time at which it were to occur; and that every idea which does occur more than once, if true once, is true at every time at which it does occur. There seems to me, I say, to be a sense in which this is so. And this seems to me to be the sense in which it is most commonly and most naturally maintained that all truths are "immutable." Professor James seems to mean to deny it, even in this sense. He seems to me constantly to speak as if there were no sense in which all truths are immutable. And I only wish to point out what seems to me to be the plainest and most obvious objection to such language.

And, first of all, there is one doctrine, which he seems to connect with this of his that "truths are mutable," with regard to which I fully agree with him. He seems very anxious to insist that reality is mutable: that it does change, and that it is not irrational to hope that in the future it will be different from and much better than it is now. And this seems to me to be quite undeniable. It seems to me quite certain that I do have ideas at one time which I did not have at another; that change, therefore, does really occur. It seems to me quite certain that in the future many things will be different from what they are now; and I see no reason to think that they may not be much better. There is much misery in the world now; and I think it is quite possible that some day there will really be much less. This view that reality is mutable, that facts do change, that some things have properties at one time which they do not have at other times, seems to me certainly true. And so far, therefore, as Professor James merely means to assert this obvious fact, I have no objection to his view. Some philosophers, I think, have really implied the denial of this fact. All those who deny the reality of time do seem to me to imply that nothing really changes or can change—that, in fact, reality is wholly immutable. And so far as Professor James is merely protesting against this view, I should, therefore, agree with him.

But I think it is quite plain that he does not mean merely this, when he says that truth is mutable. No one would choose this way of expressing himself if he merely meant to say that some things are mutable. Truth, Professor James has told us, is a property of certain of our ideas. And those of our ideas, which are true or false, are certainly only a part of the Universe. Other things in the Universe might, therefore, change, even if our ideas never changed in respect of this property. And our ideas themselves do undoubtedly change in some respects. A given idea exists in my mind at one moment and does not exist in it at another. At one moment it is in my mind and not in somebody else's, and at another in somebody else's and not in mine. I sometimes think of the truth that twice two are four when I am in one mood, and sometimes when I am in another. I sometimes think of it in connection with one set of ideas and sometimes in connection with another set. Ideas, then, are constantly changing in some respects. They come and go; and at one time they stand in a given relation to other things or ideas, to which at another time they do not stand in that relation. In this sense, any given idea may certainly have a property at one time which it has not got at another time. All this seems obvious; and all this cannot be admitted, without admitting that reality is mutable—that some things change. But obviously it does not seem to follow from this that there is no respect in which ideas are immutable. It does not seem to follow that because ideas, and other things, change some of their properties, they necessarily change that one which we are considering—namely, "truth." It does not follow that a given idea, which has the property of truth at one time, ever exists at any other time without having that property. And yet that this does happen seems to be part of what is meant by saying that truth is mutable. Plainly, therefore, to say this is to say something quite different from saying that some things are mutable. Even, therefore, if we admit that some things are mutable, it is still open to consider whether truth is so. And this is what I want now to consider. Is it the case that an idea which exists at one time, and is true then, ever exists at any other time, without being true? Is it the case that any idea ever changes from true to false? That it has the property of being true on one of the occasions when it exists, and that it has not this property, but that of being false instead, on some other occasion when it exists?

In order to answer this question clearly, it is, I think, necessary to make still another distinction. It does certainly seem to be true, in a sense, that a given idea may be true on one occasion and false on another. We constantly speak as if there were cases in which a given thing was true on one occasion and false on another; and I think it cannot be denied that, when we so speak, we are often expressing in a perfectly proper and legitimate manner something which is undeniably true. It is true now, I might say, that I am in this room; but to-morrow this will not be true. It is true now that men are often very miserable; but perhaps in some future state of society this will not be true. These are perfectly natural forms of expression, and what they express is something which certainly may be true. And yet what they do apparently assert is that something or other, which is true at one time, will not, or perhaps will not, be true at another. We constantly use such expressions, which imply that what is true at one time is not true at another; and it is certainly legitimate to use them. And hence, I think, we must admit that, in a sense, it is true that a thing may be true at one time which is not true at another; in that sense, namely, in which we use these expressions. And it is, I think, also plain that these things, which may be true at one time and false at another, may, in a sense, be ideas. We might even say: The idea that I am in this room, is true now; but to-morrow it will not be true. We might say this without any strain on language. In any ordinary book—indeed, in any philosophical book, where the subject we are at present discussing was not being expressly discussed—such expressions do, I think, constantly occur. And we should pass them, without any objection. We should at once understand what they meant, and treat them as perfectly natural expressions of things undeniably true. We must, then, I think, admit that, in a sense, an idea may be true at one time, and false at another. The question is: In what sense? What is the truth for which these perfectly legitimate expressions stand?

It seems to me that in all these cases, so far as we are not merely talking of facts, but of true ideas, that the "idea" which we truly say to be true at one time and false at another, is merely the idea of a sentence—that is, of certain words. And we do undoubtedly call words "true." The words "I am at a meeting of the Aristotelian Society" are true, if I use them now; but if I use the same words to-morrow, they would not be true. The words "George III is king of England" were true in 1800, but they are not true now. That is to say, a given set of words may undoubtedly be true at one time, and false at another; and since we may have ideas of words as well as of other things, we may, in this sense, say the same of certain of our "ideas." We may say that some of our "ideas" (namely those of words) are true at one time and not true at another.

But is it conceivable that Professor James merely meant to assert that the same words are sometimes true at one time and false at another? Can this be all he means by saying that truth is mutable? I do not think it can possibly be so. No one, I think, in definitely discussing the mutability of truth, could say that true ideas were mutable, and yet mean (although he did not say so) that this proposition applied solely to ideas of words. Professor James must, I think, have been sometimes thinking that other ideas, and not merely ideas of words, do sometimes change from true to false. And this is the proposition which I am concerned to dispute. It seems to me that if we mean by an idea, not merely the idea of certain words, but the kind of idea which words express, it is very doubtful whether such an idea ever changes from true to false—whether any such idea is ever true at one time and false at another.

And plainly, in the first place, the mere fact that the same set of words, as in the instances I have given, really are true at one time and false at another, does not afford any presumption that anything which they stand for is true at one time and false at another. For the same words may obviously be used in different senses at different times; and hence though the same words, which formerly expressed a truth, may cease to express one, that may be because they now express a different idea, and not because the idea which they formerly expressed has ceased to be true. And that, in instances such as I have given, the words do change their meaning according to the time at which they are uttered or thought of, is I think, evident. If I use now the words "I am in this room," these words certainly express (among other things) the idea that my being in this room is contemporary with my present use of the words; and if I were to use the same words to-morrow, they would express the idea that my being in this room to-morrow, was contemporary with the use of them then. And since my use of them then would not be the same fact as my use of them now, they would certainly then express a different idea from that which they express now. And in general, whenever we use the present tense in its primary sense, it seems to me plain that we do mean something different by it each time we use it. We always mean (among other things) to express the idea that a given event is contemporary with our actual use of it; and since our actual use of it on one occasion is always a different fact from our actual use of it on another, we express by it a different idea each time we use it. And similarly with the past and future tenses. If anybody had said in 1807 "Napoleon is dead," he would certainly have meant by these words something different from what I mean by them when I use them now. He would have meant that Napoleon's death occurred at a time previous to his use of those words; and this would not have been true. But in this fact there is nothing to show that if he had meant by them what I mean now, his idea would not have been as true then as mine is now. And so, if I say "It will rain to-morrow," these words have a different meaning to-day from what they would have if I used them to-morrow. What we mean by "to-morrow" is obviously a different day, when we use the word on one day, from what we mean by it when we use it on another. But in this there is nothing to show that if the idea, which I now mean by "It will rain to-morrow," were to occur again to-morrow, it would not be true then, if it is true now. All this is surely very obvious. But, if we take account of it, and if we concentrate our attention not on the words but on what is meant by them, is it so certain that what we mean by them on any one occasion ever changes from true to false? If there were to occur to me to-morrow the very same idea which I now express by the words "I am in this room," is it certain that this idea would not be as true then as it is now? It is perhaps true that the whale of what I mean by such a phrase as this never does recur. But part of it does, and that a part which is true. Part of what I mean is Certainly identical with part of what I should mean to-morrow by saying "I was in that room last night." And this part would be as true then, as it is now. And is there any part, which, if it were to recur at any time, would not then be true, though it Is true now? In the case of all ideas or parts of ideas, which ever do actually recur, can we find a single instance of one, which is plainly true at one of the times when it occurs, and yet not true at another? I cannot think of any such instance. And on the other hand this very proposition that any idea (other than mere words) which is true once, would be true at any time, seems to me to be one of those truths of which Professor James has spoken as having an "eternal," "absolute," "unconditional" character—as being "perceptually obvious at a glance" and needing "no sense-verification." Just as we know that, if a particular colour differs more from black than from grey at one time, the same colour would differ more from black than from grey at any time, so, it seems to me, we can see that, if a particular idea is true at one time, the same idea would be true at any time.

It seems to me, then, that if we mean by an idea, not mere words, but the kind of idea which words express, any idea, which is true at one time when it occurs, would be true at any time when it were to occur; and that this is so, even though it is an idea, which refers to facts which are mutable. My being in this room is a fact which is now, but which certainly has not been at every time and will not be at every time. And the words "I am in this room," though they express a truth now, would not have expressed one if I had used them yesterday, and will not if I use them to-morrow. But if we consider the idea which these words now express—namely, the idea of the connection of my being in this room with this particular time—it seems to me evident that anybody who had thought of that connection at any time in the past, would have been thinking truly, and that anybody who were to think of it at any time in the future would be thinking truly. This seems to me to be the sense in which truths are immutable—in which no idea can change from true to false. And I think Professor James means to deny of truths generally, if not of all truths, that they are immutable even in this sense. If he does not mean this there seems nothing left for him to mean, when he says that truths are mutable, except (1) that some facts are mutable, and (2) that the same words may be true at one time and false at another. And it seems to me impossible that he could speak as he does, if he meant nothing more than these two things. I believe, therefore, that he is really thinking that ideas which have been once true (ideas, and not merely words) do sometimes afterwards become false: that the very same idea is at one time true and at another false. But he certainly gives no instance which shows that this does ever occur. And how far does he mean his principle to carry him? Does he hold that this idea that Julius Caesar was murdered in the Senate-House, though true now, may, at some future time cease to be true, if it should be more profitable to the lives of future generations to believe that he died in his bed? Things like this are what his words seem to imply; and, even if he does hold that truths like this are not mutable, he never tries to tell us to what kinds of truths he would limit mutability, nor how they differ from such as this.

(III)

Finally, there remains the view that "to an unascertainable extent our truths are man-made products." And the only point I want to make about this view may be put very briefly.

It is noticeable that all the instances which Professor James gives of the ways in which, according to him, "our truths" are "made" are instances of ways in which our beliefs come into existence. In many of these ways, it would seem, false beliefs sometimes come into existence as well as true ones; and I take it Professor James does not always wish to deny this. False beliefs, I think he would say, are just as much "man-made products" as true ones: it is sufficient for his purpose if true beliefs do come into existence in the ways he mentions. And the only point which seems to be illustrated by all these instances, is that in all of them the existence of a true belief does depend in some way or other upon the previous existence of something in some man's mind. They are all of them cases in which we may truly say: This man would not have had just that belief, had not some man previously had such and such experiences, or interests, or purposes. In some cases they are instances of ways in which the existence of a particular belief in a man depends upon his own previous experiences or interests or volitions. But this does not seem to be the case in all. Professor James seems also anxious to illustrate the point that one man's beliefs often depend upon the previous experiences or interests or volitions of other men. And, as I say, the only point which seems to be definitely illustrated in all cases is that the existence of a true belief does depend, in some way or other, upon something which has previously existed in some man's mind. Almost any kind of dependence, it would seem, is sufficient to illustrate Professor James' point.

And as regards this general thesis that almost all our beliefs, true as well as false, depend, in some way or other, upon what has previously been in some human mind, it will, I think, be readily admitted. It is a commonplace, which, so far as I know, hardly anyone would deny. If this is all that is to be meant by saying that our true beliefs are "man-made," it must, I think, be admitted that almost all, If not quite all, really are man-made. And this is all that Professor James' instances seem to me, in fact, to show.

But is this all that Professor James means, when he says that our truths are man-made? Is it conceivable that he only means to insist upon this undeniable, and generally admitted, commonplace? It seems to me quite plain that this is not all that he means. I think he certainly means to suggest that, from the fact that we "make" our true beliefs, something else follows. And I think it is not hard to see one thing more which he does mean. I think he certainly means to suggest that we not only make our true beliefs, but also that we make them true. At least as much as this is certainly naturally suggested by his words. No one would persistently say that we make our truths, unless he meant, at least, not merely that we make our true beliefs, but also that we make them true—unless he meant not merely that the existence of our true beliefs, but also that their truth, depended upon human conditions. This, it seems to me, is one consequence which Professor James means us to draw from the commonplace that the existence of our true beliefs depends upon human conditions. But does this consequence, in fact, follow from that commonplace? From the fact that we make our true beliefs, does it follow that we make them true?

In one sense, undoubtedly, even this does follow. If we say (as we may say) that no belief can be true, unless it exists, then it follows that, in a sense, the truth of a belief must always depend upon any conditions upon which its existence depends. If, therefore, the occurrence of a belief depends upon human conditions, so, too, must its truth. If the belief had never existed, it would never have been true; and therefore its truth must, in a sense, depend upon human conditions in exactly the same degree in which its existence depends upon them. This is obvious. But is this all that is meant? Is this all that would be suggested to us by telling us that we make our beliefs true?

It is easy to see that it is not. I may have the belief that it will rain to-morrow. And I may have "made" myself have this belief. It may be the case that I should not have had it, but for peculiarities in my past experiences, in my interests and my volitions. It may be the case that I should not have had it, but for a deliberate attempt to consider the question whether it will rain or not. This may easily happen. And certainly this particular belief of mine would not have been true, unless it existed. Its truth, therefore, depends, in a sense, upon any conditions upon which its existence depends. And this belief may be true. It will be true, if It does rain to-morrow. But, in spite of all these reasons, would anyone think of saying that, in case it is true, I had made it true? Would anyone say that I had had any hand at all in making it true? Plainly no one would. We should say that I had a hand in making it true, if and only If I had a hand in making the rain fall. In every case in which we believe in the existence of anything, past or future, we should say that we had helped to make the belief true, if and only if we had helped to cause the existence of the fact which, in that belief, we believed did exist or would exist. Surely this is plain. I may believe that the sun will rise to-morrow. And I may have had a hand in "making" this belief; certainly it often depends for its existence upon what has been previously in my mind. And if the sun does rise, my belief will have been true. I have, therefore, had a hand in making a true belief. But would anyone say that, therefore, I had a hand in making this belief true? Certainly no one would. No one would say that anything had contributed to make this belief true, except those conditions (whatever they may be) which contributed to making the sun actually rise.

It is plain, then, that by "making a belief true," we mean something quite different from what Professor James means by "making" that belief. Conditions which have a hand in making a given true belief, may (it appears) have no hand at all in making it true; and conditions which have a hand in making it true may have no hand at all in making it. Certainly this is how we use the words. We should never say that we had made a belief true, merely because we had made the belief. But now, which of these two things does Professor James mean? Does he mean merely the accepted commonplace that we make our true beliefs, in the sense that almost all of them depend for their existence on what has been previously in some human mind? Or does he mean also that we make them true—that their truth also depends on what has been previously in some human mind?

I cannot help thinking that he has the latter, and not only the former in his mind. But, then, what does this involve? If his instances of "truth-making" are to be anything to the purpose, it should mean that, whenever I have a hand in causing one of my own beliefs, I always have to that extent a hand in making it true. That, therefore, I have a hand in actually making the sun rise, the wind blow, and the rain fall, whenever I cause my beliefs in these things. Nay, more, it should mean that, whenever I "make" a true belief about the past, I must have had a hand in making this true. And if so, then certainly I must have had a hand in causing the French Revolution, in causing my father's birth, in making Professor James write this book. Certainly he implies that some man or other must have helped in causing almost every event, in which any man ever truly believed. That it was we who made the planets revolve round the sun, who made the Alps rise, and the floor of the Pacific sink—all these things, and others like them, seem to be involved. And it is these consequences which seem to me to justify a doubt whether, in fact "our truths are to an unascertainable extent man-made." That some of our truths are man-made—indeed, a great many—I fully admit. We certainly do make some of our beliefs true. The Secretary probably had a belief that I should write this paper, and I have made his belief true by writing it. Men certainly have the power to alter the world to a certain extent; and, so far as they do this, they certainly "make true" any beliefs, which are beliefs in the occurrence of these alterations. But I can see no reason for supposing that they "make true" nearly all those of their beliefs which are true. And certainly the only reason which Professor James seems to give for believing this—namely, that the existence of almost all their beliefs depends on them—seems to be no reason for it at all. For unquestionably a man does not "make true" nearly every belief whose existence depends on him; and if so, the question which of their beliefs and how many, men do "make true" must be settled by quite other considerations.

In conclusion, I wish to sum up what seems to me to be the most important points about this "pragmatist theory of truth," as Professor James represents it. It seems to me that, in what he says about it, he has in his mind some things which are true and others which are false; and I wish to tabulate separately the principal ones which I take to be true, and the principal ones which I take to be false. The true ones seem to me to be these:—

That most of our true beliefs are useful to us; and that most of the beliefs that are useful to us are true.

That the world really does change in some respects; that facts exist at one time, which didn't and won't exist at others; and that hence the world may be better at some future time than it is now or has been in the past.

That the very same words may be true at one time and false at another—that they may express a truth at one time and a falsehood at another.

That the existence of most, if not all, of our beliefs, true as well as false, does depend upon previous events in our mental history; that we should never have had the particular beliefs we do have, had not our previous mental history been such as it was.

That the truth, and not merely the existence, of some of our beliefs, does depend upon us. That we really do make some alterations in the world, and that hence we do help to "make true" all those of our beliefs which are beliefs in the existence of these alterations.

To all of these propositions I have no objection to offer. And they seem to me to be generally admitted commonplaces. A certain class of philosophers do, indeed, imply the denial of every one of them—namely, those philosophers who deny the reality of time. And I think that part of Professor James' object is to protest against the views of these philosophers. All of these propositions do constitute a protest against such views; and so far they might be all that Professor James meant to assert. But I do not think that anyone, fairly reading through what he says, could get the impression that these things, and nothing more, were what he had in his mind. What gives colour and interest to what he says, seems to be obviously something quite different. And, if we try to find out what exactly the chief things are which give his discussion its colour and interest, it seems to me we may distinguish that what he has in his mind, wrapped up in more or less ambiguous language, are the following propositions, to all of which I have tried to urge what seem to me the most obvious objections:—

That utility is a property which distinguishes true beliefs from those which are not true; that, therefore, all true beliefs are useful, and all beliefs, which are useful, are true—by "utility" being sometimes meant "utility on at least one occasion," sometimes "utility in the long run," sometimes "utility for some length of time."

That all beliefs which are useful for some length of time are true.

That utility is the only property which all true beliefs have in common: that, therefore, if it were useful to me to believe in Professor James' existence, this belief would be true, even if he didn't exist; and that, if it were not useful to me to believe this, the belief would be false, even if he did.

That the beliefs, which we express by words, and not merely the words themselves, may be true at one time and not true at another; and that this is a general rule, though perhaps there may be some exceptions.

That whenever the existence of a belief depends to some extent on us, then also the truth of that belief depends to some extent on us; in the sense in which this implies, that, when the existence of my belief that a shower will fall depends upon me, then, if this belief is true, I must have had a hand in making the shower fall: that, therefore, men must have had a hand in making to exist almost every fact which they ever believe to exist.

[1] Pragmatism: A New Name for some Old Ways of Thinking: Popular Lectures on Philosophy. By William James. Longmans, Green, and Co., 1907

[HUME'S PHILOSOPHY]

In both of his two books on the Human Understanding, Hume had, I think, one main general object. He tells us that it was his object to discover "the extent and force of human understanding," to give us "an exact analysis of its powers and capacity." And we may, I think, express what he meant by this in the following way. He plainly held (as we all do) that some men sometimes entertain opinions which they cannot know to be true. And he wished to point out what characteristics are possessed by those of our opinions which we can know to be true, with a view of persuading us that any opinion which does not possess any of these characteristics is of a kind which we cannot know to be so. He thus tries to lay down certain rules to the effect that the only propositions which we can, any of us, know to be true are of certain definite kinds. It is in this sense, I think, that he tries to define the limits of human understanding.

With this object he, first of all, divides all the propositions, which we can even so much as conceive, into two classes. They are all, he says, either propositions about "relations of ideas" or else about "matters of fact." By propositions about "relations of ideas" he means such propositions as that twice two are four, or that black differs from white; and it is, I think, easy enough to see, though by no means easy to define, what kind of propositions it is that he means to include in this division. They are, he says, the only kind of propositions with regard to which we can have "intuitive" or "demonstrative" certainty. But the vast majority of the propositions in which we believe and which interest us most, belong to the other division: they are propositions about "matters of fact." And these again he divides into two classes. So far as his words go, this latter division is between "matters of fact, beyond the present testimony of our senses, or the records of our memory," on the one hand, and matters of fact for which we have the evidence of our memory or senses, on the other. But it is, I think, quite plain that these words do not represent quite accurately the division which he really means to make. He plainly intends to reckon along with facts for which we have the evidence of our senses all facts for which we have the evidence of direct observation—such facts, for instance, as those which I observe when I observe that I am angry or afraid, and which cannot be strictly said to be apprehended by my senses. The division, then, which he really intends to make is (to put it quite strictly) into the two classes—(1) propositions which assert some matter of fact which I am (in the strictest sense) observing at the moment, or which I have so observed in the past and now remember; and (2) propositions which assert any matter of fact which I am not now observing and never have observed, or, if I have, have quite forgotten.

We have, then, the three classes—(1) propositions which assert "relations of ideas"; (2) propositions which assert "matters of fact" for which we have the evidence of direct observation or personal memory; (3) propositions which assert "matters of fact" for which we have not this evidence. And as regards propositions of the first two classes, Hume does not seem to doubt our capacity for knowledge. He does not doubt that we can know some (though, of course, not all) propositions about "relations of ideas" to be true; he never doubts, for instance, that we can know that twice two are four. And he generally assumes also that each of us can know the truth of all propositions which merely assert some matter of fact which we ourselves are, in the strictest sense, directly observing, or which we have so observed and now remember. He does, indeed, in one place, suggest a doubt whether our memory is ever to be implicitly trusted, but he generally assumes that it always can. It is with regard to propositions of the third class that he is chiefly anxious to determine which of them (if any) we can know to be true and which not. In what cases can any man know any matter of fact which he himself has not directly observed? It is Hume's views on this question which form, I think, the main interest of his philosophy.

He proposes, first of all, by way of answer to it, a rule, which may, I think, be expressed as follows: No man, he says, can ever know any matter of fact, which he has not himself observed, unless he can know that it is connected by "the relation of cause and effect," with some fact which he has observed. And no man can ever know that any two facts are connected by this relation, except by the help of his own past experience. In other words, if I am to know any fact, A, which I have not myself observed, my past experience must give me some foundation for the belief that A is causally connected with some fact, B, which I have observed. And the only kind of past experience which can give me any foundation for such a belief is, Hume seems to say, as follows: I must, he says, have found facts like A "constantly conjoined" in the past with facts like B. This is what he says; but we must not, I think, press his words too strictly. I may, for instance, know that A is probably a fact, even where the conjunction of facts like it with facts like B has not been quite constant. Or instead of observing facts like A conjoined with facts like B, I may have observed a whole series of conjunctions—for instance, between A and C, C and D, D and E, and E and B; and such a series, however long, will do quite as well to establish a causal connection between A and B, as if I had directly observed conjunctions between A and B themselves. Such modifications as this, Hume would, I think, certainly allow. But, allowing for them, his principle is, I think, quite clear. I can, he holds, never know any fact whatever, which I have not myself observed, unless I have observed similar facts in the past and have observed that they were "conjoined" (directly or indirectly) with facts similar to some fact which I do now observe or remember. In this sense, he holds, all our knowledge of facts, beyond the reach of our own observation, is founded on experience.

This is Hume's primary principle. But what consequences does he think will follow from it, as to the kind of facts, beyond our own observation, which we can know? We may, I think, distinguish three entirely different views as to its consequences, which he suggests in different parts of his work.

In the first place, where he is specially engaged in explaining this primary principle, he certainly seems to suppose that all propositions of the kind, which we assume most universally in everyday life, may be founded on experience in the sense required. He supposes that we have this foundation in experience for such beliefs as that "a stone will fall, or fire burn"; that Julius Caesar was murdered; that the sun will rise to-morrow; that all men are mortal He speaks as if experience did not merely render such beliefs probable, but actually proved them to be true. The "arguments from experience" in their favour are, he says, such as "leave no room for doubt or opposition." The only kinds of belief, which he definitely mentions as not founded on experience, are "popular superstitions" on the one hand, and certain religious and philosophical beliefs, on the other. He seems to suppose that a few (a very few) religious beliefs may, perhaps, be founded on experience. But as regards most of the specific doctrines of Christianity, for example, he seems to be clear that they are not so founded. The belief in miracles is not founded on experience; nor is the philosophical belief that every event is caused by the direct volition of the Deity. In short, it would seem, that in this doctrine that our knowledge of unobserved facts is confined to such as are "founded on experience," he means to draw the line very much where it is drawn by the familiar doctrine which is called "Agnosticism." We can know such facts as are asserted in books on "history, geography or astronomy," or on "politics, physics and chemistry," because such assertions may be "founded on experience"; but we cannot know the greater part of the facts asserted in books "of divinity or school metaphysics," because such assertions have no foundation in experience.

This, I think, was clearly one of Hume's views. He meant to fix the limits of our knowledge at a point which would exclude most religious propositions and a great many philosophical ones, as incapable of being known; but which would include all the other kinds of propositions, which are most universally accepted by common-sense, as capable of being known. And he thought that, so far as matters of fact beyond the reach of our personal observation are concerned, this point coincided with that at which the possibility of "foundation on experience" ceases.

But, if we turn to another part of his work, we find a very different view suggested. In a quite distinct section of both his books, he investigates the beliefs which we entertain concerning the existence of "external objects." And he distinguishes two different kinds of belief which may be held on this subject. "Almost all mankind, and philosophers themselves, for the greatest part of their lives," believe, he says, that "the very things they feel and see" are external objects, in the sense that they continue to exist, even when we cease to feel or see them. Philosophers, on the other hand, have been led to reject this opinion and to suppose (when they reflect) that what we actually perceive by the senses never exists except when we perceive it, but that there are other external objects, which do exist independently of us, and which cause us to perceive what we do perceive. Hume investigates both of these opinions, at great length in the Treatise, and much more briefly in the Enquiry, and comes to the conclusion, in both books, that neither of them can be "founded on experience," in the sense he has defined. As regards the first of them, the vulgar opinion, he does seem to admit in the Treatise that it is, in a sense, founded on experience; but not, he insists, in the sense defined. And he seems also to think that, apart from this fact, there are conclusive reasons for holding that the opinion cannot be true. And as regards the philosophical opinion, he says that any belief in external objects, which we never perceive but which cause our perceptions, cannot possibly be founded on experience, for the simple reason that if it were, we should need to have directly observed some of these objects and their "conjunction" with what we do perceive, which ex hypothesi, we cannot have done, since we never do directly observe any external object.

Hume, therefore, concludes, in this part of his work, that we cannot know of the existence of any "external object" whatever. And though in all that he says upon this subject, he is plainly thinking only of material objects, the principles by which he tries to prove that we cannot know these must, I think, prove equally well that we cannot know any "external object" whatever—not even the existence of any other human mind. His argument is: We cannot directly observe any object whatever, except such as exist only when we observe them; we cannot, therefore, observe any "constant conjunctions" except between objects of this kind: and hence we can have no foundation in experience for any proposition which asserts the existence of any other kind of object, and cannot, therefore, know any such proposition to be true. And this argument must plainly apply to all the feelings, thoughts and perceptions of other men just as much as to material objects. I can never know that any perception of mine, or anything which I do observe, must have been caused by any other man, because I can never directly observe a "constant conjunction" between any other man's thoughts or feelings or intentions and anything which I directly observe: I cannot, therefore, know that any other man ever had any thoughts or feelings—or, in short, that any man beside myself ever existed. The view, therefore, which Hume suggests in this part of his work, flatly contradicts the view which he at first seemed to hold. He now says we cannot know that a stone will fall, that fire will burn, or the sun will rise to-morrow. All that I can possibly know, according to his present principles, is that I shall see a stone fall, shall feel the fire burn, shall see the sun rise to-morrow. I cannot even know that any other men will see these things; for I cannot know that any other men exist. For the same reason, I cannot know that Julius Caesar was murdered, or that all men are mortal. For these are propositions asserting "external" facts—facts which don't exist only at the moment when I observe them; and, according to his present doctrine, I cannot possibly know any such proposition to be true. No man, in short, can know any proposition about "matters of fact" to be true, except such as merely assert something about his own states of mind, past, present or future—about these or about what he himself has directly observed, is observing, or will observe.

Here, therefore, we have a very different view suggested, as to the limits of human knowledge. And even this is not all. There is yet a third view, inconsistent with both of these, which Hume suggests in some parts of his work.

So far as we have yet seen, he has not in any way contradicted his original supposition that we can know some matters of fact, which we have never ourselves observed. In the second theory, which I have just stated, he does not call in question the view that I can know all such matters of fact as I know to be causally connected with facts which I have observed, nor the view that I can know some facts to be thus causally connected. All that he has done is to question whether I can know any external fact to be causally connected with anything which I observe; he would still allow that I may be able to know that future states of my own, or past states, which I have forgotten, are causally connected with those which I now observe or remember; and that I may know therefore, in some cases, what I shall experience in the future, or have experienced in the past but have now forgotten. But in some parts of his work he does seem to question whether any man can know even as much as this: he seems to question whether we can ever know any fact whatever to be causally connected with any other fact. For, after laying it down, as we saw above, that we cannot know any fact, A, to be causally connected with another, B, unless we have experienced in the past a constant conjunction between facts like A and facts like B, he goes on to ask what foundation we have for the conclusion that A and B are causally connected, even when we have in the past experienced a constant conjunction between them. He points out that from the fact that A has been constantly conjoined with B in the past, it does not follow that it ever will be so again. It does not follow, therefore, that the two really are causally connected in the sense that, when the one occurs, the other always will occur also. And he concludes, for this and other reasons, that no argument can assure us that, because they have been constantly conjoined in the past, therefore they really are causally connected. What, then, he asks, is the foundation for such an inference? Custom, he concludes, is the only foundation. It is nothing but custom which induces us to believe that, because two facts have been constantly conjoined on many occasions, therefore they will be so on all occasions. We have, therefore, no better foundation than custom for any conclusion whatever as to facts which we have not observed. And can we be said really to know any fact, for which we have no better foundation than this? Hume himself, it must be observed, never says that we can't. But he has been constantly interpreted as if the conclusion that we can't really know any one fact to be causally connected with any other, did follow from this doctrine of his. And there is, I think, certainly much excuse for this interpretation in the tone in which he speaks. He does seem to suggest that a belief which is merely founded on custom, can scarcely be one which we know to be true. And, indeed, he owns himself that, when he considers that this is our only foundation for any such belief, he is sometimes tempted to doubt whether we do know any fact whatever, except those which we directly observe. He does, therefore, at least suggest the view that every man's knowledge is entirely confined to those facts, which he is directly observing at the moment, or which he has observed in the past, and now remembers.

We see, then, that Hume suggests, at least, three entirely different views as to the consequences of his original doctrine. His original doctrine was that, as regards matters of fact beyond the reach of our own actual observation, the knowledge of each of us is strictly limited to those for which we have a basis in our own experience. And his first view as to the consequences of this doctrine was that it does show us to be incapable of knowing a good many religious and philosophical propositions, which many men have claimed that they knew; but that it by no means denies our capacity of knowing the vast majority of facts beyond our own observation, which we all commonly suppose that we know. His second view, on the other hand, is that it cuts off at once all possibility of our knowing the vast majority of these facts; since he implies that we cannot have any basis in experience for asserting any external fact whatever—any fact, that is, except facts relating to our own actual past and future observations. And his third view is more sceptical still, since it suggests that we cannot really know any fact whatever, beyond the reach of our present observation or memory, even where we have a basis in experience for such a fact: it suggests that experience cannot ever let us know that any two things are causally connected, and therefore that it cannot give us knowledge of any fact based on this relation.

What are we to think of these three views, and of the original doctrine from which Hume seems to infer them?

As regards the last two views, it may perhaps be thought that they are too absurd to deserve any serious consideration. It is, in fact, absurd to suggest that I do not know any external facts whatever; that I do not know, for instance, even that there are any men beside myself. And Hume himself, it might seem, does not seriously expect or wish us to accept these views. He points out, with regard to all such excessively sceptical opinions that we cannot continue to believe them for long together—that, at least, we cannot, for long together, avoid believing things flatly inconsistent with them. The philosopher may believe, when he is philosophising, that no man knows of the existence of any other man or of any material object; but at other times he will inevitably believe, as we all do, that he does know of the existence of this man and of that, and even of this and that material object. There can, therefore, be no question of making all our beliefs consistent with such views as this of never believing anything that is inconsistent with them. And it may, therefore, seem useless to discuss them. But in fact, it by no means follows that, because we are not able to adhere consistently to a given view, therefore that view is false; nor does it follow that we may not sincerely believe it, whenever we are philosophising, even though the moment we cease to philosophise, or even before, we may be forced to contradict it. And philosophers do, in fact, sincerely believe such things as this—things which flatly contradict the vast majority of the things which they believe at other times. Even Hume, I think, does sincerely wish to persuade us that we cannot know of the existence of external material objects—that this is a philosophic truth, which we ought, if we can, so long as we are philosophising, to believe. Many people, I think, are certainly tempted, in their philosophic moments, to believe such things; and, since this is so, it is, I think, worth while to consider seriously what arguments can be brought against such views. It is worth while to consider whether they are views which we ought to hold as philosophical opinions, even if it be quite certain that we shall never be able to make the views which we entertain at other times consistent with them. And it is the more worth while, because the question how we can prove or disprove such extreme views as these, has a bearing on the question how we can, in any case whatever, prove or disprove that we do really know, what we suppose ourselves to know.

What arguments, then, are there for or against the extreme view that no man can know any external fact whatever; and the still more extreme view that no man can know any matter of fact whatever, except those which he is directly observing at the moment, or has observed in the past and now remembers?

It may be pointed out, in the first place, that, if these views are true, then at least no man can possibly know them to be so. What these views assert is that I cannot know any external fact whatever. It follows, therefore, that I cannot know that there are any other men, beside myself, and that they are like me in this respect. Any philosopher who asserts positively that other men, equally with himself, are incapable of knowing any external facts, is, in that very assertion, contradicting himself, since he implies that he does know a great many facts about the knowledge of other men. No one, therefore, can be entitled to assert positively that human knowledge is limited in this way, since, in asserting it positively, he is implying that his own knowledge is not so limited. It cannot be proper, even in our philosophic moments, to take up such an attitude as this.

No one, therefore, can know positively that men in general, are incapable of knowing external facts. But still, although we cannot know it, it remains possible that the view should be a true one. Nay, more, it remains possible that a man should know that he himself is incapable of knowing any external facts, and that, if there are any other men whose faculties are only similar to his own, they also must be incapable of knowing any. The argument just used obviously does not apply against such a position as this. It only applies against the position that men in general positively are incapable of knowing external facts: it does not apply against the position that the philosopher himself is incapable of knowing any, or against the position that there are possibly other men in the same case, and that, if their faculties are similar to the philosopher's, they certainly would be in it. I do not contradict myself by maintaining positively that I know no external facts, though I do contradict myself if I maintain that I am only one among other men, and that no man knows any external facts. So far, then, as Hume merely maintains that he is incapable of knowing any external facts, and that there may be other men like him in this respect, the argument just used is not valid against his position. Can any conclusive arguments be found against it?

It seems to me that such a position must, in a certain sense, be quite incapable of disproof. So much must be granted to any sceptic who feels inclined to hold it. Any valid argument which can be brought against it must be of the nature of a petitio principii: it must beg the question at issue. How is the sceptic to prove to himself that he does know any external facts? He can only do it by bringing forward some instance of an external fact, which he does know; and, in assuming that he does know this one, he is, of course, begging the question. It is therefore quite impossible for any one to prove, in one strict sense of the term, that he does know any external facts. I can only prove that I do, by assuming that in some particular instance, I actually do know one. That is to say, the so-called proof must assume the very thing which it pretends to prove. The only proof that we do know external facts lies in the simple fact that we do know them. And the sceptic can, with perfect internal consistency, deny that he does know any. But it can, I think, be shown that he has no reason for denying it. And in particular it may, I think, be easily seen that the arguments which Hume uses in favour of this position have no conclusive force.

To begin with, his arguments, in both cases, depend upon the two original assumptions, (1) that we cannot know any fact, which we have not observed, unless we know it to be causally connected with some fact which we have observed, and (2) that we have no reason for assuming any causal connection, except where we have experienced some instances of conjunction between the two facts connected. And both of these assumptions may, of course, be denied. It is just as easy to deny them, as to deny that I do know any external facts. And, if these two assumptions did really lead to the conclusion that I cannot know any, it would, I think, be proper to deny them: we might fairly regard the fact that they led to this absurd conclusion as disproving them. But, in fact, I think it may be easily seen that they do not lead to it.

Let us consider, first of all, Hume's most sceptical argument (the argument which he merely suggests). This argument suggests that, since our only reason for supposing two facts to be causally connected is that we have found them constantly conjoined in the past, and since it does not follow from the fact that they have been conjoined ever so many times, that they always will be so, therefore we cannot know that they always will be so, and hence cannot know that they are causally connected. But obviously the conclusion does not follow. We must, I think, grant the premiss that, from the fact that two things have been conjoined, no matter how often, it does not strictly follow that they always are conjoined. But it by no means follows from this that we may not know that, as a matter of fact, when two things are conjoined sufficiently often, they are also always conjoined. We may quite well know many things which do not logically follow from anything else which we know. And so, in this case, we may know that two things are causally connected, although this does not logically follow from our past experience, nor yet from anything else that we know. And, as for the contention that our belief in causal connections is merely based on custom, we may, indeed, admit that custom would not be a sufficient reason for concluding the belief to be true. But the mere fact (if it be a fact) that the belief is only caused by custom, is also no sufficient reason for concluding that we can not know it to be true. Custom may produce beliefs, which we do know to be true, even though it be admitted that it does not necessarily produce them.

And as for Hume's argument to prove that we can never know any external object to be causally connected with anything which we actually observe, it is, I think, obviously fallacious. In order to prove this, he has, as he recognises, to disprove both of two theories. He has, first of all, to disprove what he calls the vulgar theory—the theory that we can know the very things which we see or feel to be external objects; that is to say, can know that these very things exist at times when we do not observe them. And even here, I think, his arguments are obviously inconclusive. But we need not stay to consider them, because, in order to prove that we cannot know any external objects, he has also to disprove what he calls the philosophic theory—the theory that we can know things which we do observe, to be caused by external objects which we never observe. If, therefore, his attempt to disprove this theory fails, his proof that we cannot know any external objects also fails; and I think it is easy to see that his disproof does fail. It amounts merely to this: That we cannot, ex hypothesi, ever observe these supposed external objects, and therefore cannot observe them to be constantly conjoined with any objects which we do observe. But what follows from this? His own theory about the knowledge of causal connection is not that in order to know A to be the cause of B, we must have observed A itself to be conjoined with B; but only that we must have observed objects like A to be constantly conjoined with objects like B. And what is to prevent an external object from being like some object which we have formerly observed? Suppose I have frequently observed a fact like A to be conjoined with a fact like B: and suppose I now observe B, on an occasion when I do not observe anything like A. There is no reason, on Hume's principles, why I should not conclude that A does exist on this occasion, even though I do not observe it; and that it is, therefore, an external object. It will, of course, differ from any object which I have ever observed, in respect of the simple fact that it is not observed by me, whereas they were. There is, therefore, this one respect in which it must be unlike anything which I have ever observed. But Hume has never said anything to show that unlikeness in this single respect is sufficient to invalidate the inference. It may quite well be like objects which I have observed in all other respects; and this degree of likeness may, according to his principles, be quite sufficient to justify us in concluding its existence. In short, when Hume argues that we cannot possibly learn by experience of the existence of any external objects, he is, I think, plainly committing the fallacy of supposing that, because we cannot, ex hypothesis have ever observed any object which actually is "external," therefore we can never have observed any object like an external one. But plainly we may have observed objects like them in all respects except the single one that these have been observed whereas the others have not. And even a less degree of likeness than this would, according to his principles, be quite sufficient to justify an inference of causal connection.

Hume does not, therefore, bring forward any arguments at all sufficient to prove either that he cannot know any one object to be causally connected with any other or that he cannot know any external fact. And, indeed, I think it is plain that no conclusive argument could possibly be advanced in favour of these positions. It would always be at least as easy to deny the argument as to deny that we do know external facts. We may, therefore, each one of us, safely conclude that we do know external facts; and, if we do, then there is no reason why we should not also know that other men do the same. There is no reason why we should not, in this respect, make our philosophical opinions agree with what we necessarily believe at other times. There is no reason why I should not confidently assert that I do really know some external facts, although I cannot prove the assertion except by simply assuming that I do. I am, in fact, as certain of this as of anything; and as reasonably certain of it. But just as I am certain that I do know some external facts, so I am also certain that there are others which I do not know. And the question remains: Does the line between the two fall, where Hume says it falls? Is it true that the only external facts I know are facts for which I have a basis in my own experience? And that I cannot know any facts whatever, beyond the reach of my own observation and memory, except those for which I have such a basis?

This, it seems to me, is the most serious question which Hume raises. And it should be observed that his own attitude towards it is very different from his attitude towards the sceptical views which we have just been considering. These sceptical views he did not expect or wish us to accept, except in philosophic moments. He declares that we cannot, in ordinary life, avoid believing things which are inconsistent with them; and, in so declaring, he, of course, implies incidentally that they are false: since he implies that he himself has a great deal of knowledge as to what we can and cannot believe in ordinary life. But, as regards the view that our knowledge of matters of fact beyond our own observation is entirely confined to such as are founded on experience, he never suggests that it is impossible that all our beliefs should be consistent with this view, and he does seem to think it eminently desirable that they should be. He declares that any assertion with regard to such matters, which is not founded on experience, can be nothing but "sophistry and illusion"; and that all books which are composed of such assertions should be "committed to the flames." He seems, therefore, to think that here we really have a test by which we may determine what we should or should not believe, on all occasions: any view on such matters, for which we have no foundation in experience, is a view which we cannot know to be even probably true, and which we should never accept, if we can help it. Is there any justification for this strong view?

It is, of course, abstractly possible that we do really know, without the help of experience, some matters of fact, which we never have observed. Just as we know matters of fact, which we have observed, without the need of any further evidence, and just as we know, for instance, that 2+2=4, without the need of any proof, it is possible that we may know, directly and immediately, without the need of any basis in experience, some facts which we never have observed. This is certainly possible, in the same sense in which it is possible that I do not really know any external facts: no conclusive disproof can be brought against either position. We must make assumptions as to what facts we do know and do not know, before we can proceed to discuss whether or not all of the former are based on experience; and none of these assumptions can, in the last resort, be conclusively proved. We may offer one of them in proof of another; but it will always be possible to dispute the one which we offer in proof. But there are, in fact, certain kinds of things which we universally assume that we do know or do not know, just as we assume that we do know some external facts; and if among all the things which we know as certainly as this, there should turn out to be none for which we have no basis in experience, Hume's view would I think, be as fully proved as it is capable of being. The question is: Can it be proved in this sense? Among all the facts beyond our own observation, which we know most certainly, are there any which are certainly not based upon experience? For my part, I confess, I cannot feel certain what is the right answer to this question: I cannot tell whether Hume was right or wrong. But if he was wrong—if there are any matters of fact, beyond our own observation, which we know for certain, and which yet we know directly and immediately, without any basis in experience, we are, I think, faced with an eminently interesting problem. For it is, I think, as certain as anything can be that there are some kinds of facts with regard to which Hume was right—that there are some kinds of facts which we cannot know without the evidence of experience. I could not know, for instance, without some such evidence, such a fact as that Julius Caesar was murdered. For such a fact I must, in the first instance, have the evidence of other persons; and if I am to know that their evidence is trustworthy, I must have some ground in experience for supposing it to be so. There are, therefore, some kinds of facts which we cannot know without the evidence of experience and observation. And if it is to be maintained that there are others, which we can know without any such evidence, it ought to be pointed out exactly what kind of facts these are, and in what respects they differ from those which we cannot know without the help of experience. Hume gives us a very clear division of the kinds of propositions which we can know to be true. There are, first of all, some propositions which assert "relations of ideas "; there are, secondly, propositions which assert "matters of fact" which we ourselves are actually observing, or have observed and now remember; and there are, thirdly, propositions which assert "matters of fact" which we have never actually observed, but for believing in which we have some foundation in our past observations. And it is, I think, certain that some propositions, which we know as certainly as we know anything, do belong to each of these three classes. I know, for instance, that twice two are four; I know by direct observation that I am now seeing these words, that I am writing, and by memory that this afternoon I saw St. Paul's; and I know also that Julius Caesar was murdered, and I have some foundation in experience for this belief, though I did not myself witness the murder. Do any of those propositions, which we know as certainly as we know these and their like, not belong to either of these three classes? Must we add a fourth class consisting of propositions which resemble the two last, in respect of the fact that they do assert "matters of fact," but which differ from them, in that we know them neither by direct observation nor by memory, nor yet as a result of previous observations? There may, perhaps, be such a fourth class; but, if there is, it is, I think, eminently desirable that it should be pointed out exactly what propositions they are which we do know in this way; and this, so far as I know, has never yet been done, at all clearly, by any philosopher.

[THE STATUS OF SENSE-DATA]

The term "sense-data" is ambiguous; and therefore I think I had better begin by trying to explain what the class of entities is whose status I propose to discuss.

There are several different classes of mental events, all of which, owing to their intrinsic resemblance to one another in certain respects, may, in a wide sense, be called "sensory experiences," although only some among them would usually be called "sensations." There are (1) those events, happening in our minds while we are awake, which consist in the experiencing of one of those entities, which are usually called "images," in the narrowest sense of the term. Everybody distinguishes these events from sensations proper; and yet everybody admits that "images" intrinsically resemble the entities which are experienced in sensations proper in some very important respect. There are (2) the sensory experiences we have in dreams, some of which would certainly be said to be experiences of images, while others might be said to be sensations. There are (3) hallucinations, and certain classes of illusory sensory experiences. There are (4) those experiences, which used to be called the having of "after-images," but which psychologists now say ought rather to be called "after-sensations." And there are, finally, (5) that class of sensory experiences, which are immensely commoner than any of the above, and which may be called sensations proper, if we agree to use this term in such a way as to exclude experiences of my first four sorts.

Every event, of any one of these five classes, consists in the fact that an entity, of some kind or other, is experienced. The entity which is experienced may be of many different kinds; it may, for instance, be a patch of colour, or a sound, or a smell, or a taste, etc; or it may be an image of a patch of colour, an image of a sound, an image of a smell, an image of a taste, etc. But, whatever be its nature, the entity which is experienced must in all cases be distinguished from the fact or event which consists in its being experienced; since by saying that it is experienced we mean that it has a relation of a certain kind to something else. We can, therefore, speak not only of experiences of these five kinds, but also of the entities which are experienced in experiences of these kinds; and the entity which is experienced in such an experience is never identical with the experience which consists in its being experienced. But we can speak not only of the entities which are experienced in experiences of this kind, but also of the sort of entities which are experienced in experiences of this kind; and these two classes may again be different. For a patch of colour, even if it were not actually experienced, would be an entity of the same sort as some which are experienced in experiences of this kind: and there is no contradiction in supposing that there are patches of colour, which yet are not experienced; since by calling a thing a patch of colour we merely make a statement about its intrinsic quality, and in no way assert that it has to anything else any of the relations which may be meant by saying that it is experienced. In speaking, therefore, of the sort of entities which are experienced in experiences of the five kinds I have mentioned, we do not necessarily confine ourselves to those which actually are experienced in some such experience: we leave it an open question whether the two classes are identical or not. And the class of entities, whose status I wish to discuss, consists precisely of all those, whether experienced or not, which are of the same sort as those which are experienced in experiences of these five kinds.

I intend to call this class of entities the class of sensibles; so that the question I am to discuss can be expressed in the form: What is the status of sensibles? And it must be remembered that images and after-images are just as much "sensibles," in my sense of the term, as the entities which are experienced in sensations proper; and so, too, are any patches of colour, or sounds, or smells, etc, (if such there be), which are not experienced at all.

In speaking of sensibles as the sort of entities which are experienced in sensory experiences I seem to imply that all the entities which are experienced in sensory experiences have some common characteristic other than that which consists in their being so experienced. And I cannot help thinking that this is the case, in spite of the fact that it is difficult to see what intrinsic character can be shared in common by entities so different from one another as are patches of colour, sounds, smells, tastes, etc. For, so far as I can see, some non-sensory experiences may be exactly similar to sensory ones in all intrinsic respects, except that what is experienced in them is different in kind from what is experienced in any sensory experience: the relation meant by saying that in them something is experienced may be exactly the same in kind, and so may the experient. And, if this be so, it seems to compel us to admit that the distinction between sensory and non-sensory experiences is derived from that between sensibles, and non-sensibles and not vice versâ. I am inclined, therefore, to think that all sensibles, in spite of the great differences between them, have some common intrinsic property, which we recognise, but which is unanalysable; and that, when we call an experience sensory, what we mean is not only that in it something is experienced in a particular way, but also that this something has this unanalysable property. If this be so, the ultimate definition of "sensibles" would be merely all entities which have this unanalysable property.

It seems to me that the term "sense-data" is often used, and may be correctly used, simply as a synonym for "sensibles"; and everybody, I think, would expect me, in discussing the status of sense-data, to discuss, among other things, the question whether there are any sensibles which are not "given." It is true that the etymology of the term "sense-data" suggests that nothing should be called a sense-datum, but what is given; so that to talk of a non-given sense-datum would be a contradiction in terms. But, of course, etymology is no safe guide either as to the actual or the correct use of terms; and it seems to me that the term "sense-data" is often, and quite properly, used merely for the sort of entities that are given in sense, and not in any way limited to those which are actually given. But though I think I might thus have used "sense-data" quite correctly instead of "sensibles," I think the latter term is perhaps more convenient; because though nobody ought to be misled by etymologies, so many people in fact are so. Moreover the term "sense-data" is sometimes limited in yet another way, viz, to the sort of sensibles which are experienced in sensations proper; so that in this sense "images" would not be "sense-data." For both these reasons, I think it is perhaps better to drop the term "sense-data" altogether, and to speak only of "sensibles."

My discussion of the status of sensibles will be divided into two parts. I shall first consider how, in certain respects, they are related to our minds; and then I shall consider how, in certain respects, they are related to physical objects.

(I)

(1) We can, I think, distinguish pretty clearly at least one kind of relation which sensibles, of all the kinds I have mentioned, do undoubtedly sometimes have to our minds.

I do now see certain blackish marks on a whitish ground, and I hear certain sounds which I attribute to the ticking of my clock. In both cases I have to certain sensibles—certain blackish marks, in the one case, and certain sounds, in the other—a kind of relation with which we are all perfectly familiar, and which may be expressed, in the one case, by saying that I actually see the marks, and in the other, by saying that I actually hear the sounds. It seems to me quite evident that the relation to the marks which I express by saying that I see them, is not different in kind from the relation to the sounds which I express by saying that I hear them. "Seeing" and "hearing," when thus used as names for a relation which we may have to sensibles, are not names for different relations, but merely express the fact that, in the one case, the kind of sensible to which I have a certain kind of relation is a patch of colour, while, in the other case, the kind of sensible to which I have the same kind of relation is a sound. And similarly when I say that I feel warm or smell a smell these different verbs do not express the fact that I have a different kind of relation to the sensibles concerned, but only that I have the same kind of relation to a different kind of sensible. Even when I call up a visual image of a sensible I saw yesterday, or an auditory image of a sound I heard yesterday, I have to those images exactly the same kind of relation which I have to the patches of colour I now see and which I had yesterday to those I saw then.

But this kind of relation, which I sometimes have to sensibles of all sorts of different kinds, images as well as others, is evidently quite different in kind from another relation which I may also have to sensibles. After looking at this black mark, I may turn away my head or close my eyes, and then I no longer actually see the mark I saw just now. I may, indeed, have (I myself actually do have at this moment) a visual image of the mark before my mind; and to this image I do now have exactly the same kind of relation which I had just now to the mark itself. But the image is not identical with the mark of which it is an image; and to the mark itself it is quite certain that I have not now got the same kind of relation as I had just now, when I was actually seeing it. And yet I certainly may now have to that mark itself a kind of relation, which may be expressed by saying that I am thinking of it or remembering it. I can now make judgments about it itself—the very sensible which I did see just now and am no longer seeing: as, for instance, that I did then see it and that it was different from the image of it which I am now seeing. It is, therefore, quite certain that there is a most important difference between the relation I have to a sensible when I am actually seeing or hearing it, and any relation (for there may be several) which I may have to the same sensible when I am only thinking or or remembering it. And I want to express this difference by using a particular term for the former relation. I shall express this relation, which I certainly do have to a sensible when I actually see or hear it, and most certainly do not have to it, when I only think of or remember it, by saying that there is in my mind a direct apprehension of it. I have expressly chosen this term because, so far as I know, it has not been used hitherto as a technical term; whereas all the terms which have been so used, such as "presented," "given," "perceived," seem to me to have been spoilt by ambiguity. People sometimes, no doubt, use these terms as names for the kind of relation I am concerned with. But you can never be sure, when an entity is said to be "given" or "presented" or "perceived," that what is meant is simply and solely that it has to someone that relation which sensibles do undoubtedly have to me when I actually see or hear them, and which they do not have to me when I only think of or remember them.

I have used the rather awkward expression "There is in my mind a direct apprehension of this black mark," because I want to insist that though, when I see the mark, the mark certainly has to something the fundamental relation which I wish to express by saying that it is directly apprehended, and though the event which consists in its being directly apprehended by that something is certainly a mental act of mine or which occurs in my mind, yet the something which directly apprehends it may quite possibly not be anything which deserves to be called "I" or "me." It is quite possible, I think, that there is no entity whatever which deserves to be called "I" or "me" or "my mind"; and hence that nothing whatever is ever directly apprehended by me. Whether this is so or not, depends on the nature of that relation which certainly does hold between all those mental acts which are mine, and does not hold between any of mine and any of yours; and which holds again between all those mental acts which are yours, but does not hold between any of yours and any of mine. And I do not feel at all sure what the correct analysis of this relation is. It may be the case that the relation which unites all those acts of direct apprehension which are mine, and which is what we mean to say that they have to one another when we say they are all mine, really does consist in the fact that one and the same entity is what directly apprehends in each of them: in which case this entity could properly be called "me," and it would be true to say that, when I see this black mark, I directly apprehend it. But it is also quite possible (and this seems to me to be the view which is commonest amongst psychologists) that the entity which directly apprehends, in those acts of direct apprehension which are mine, is numerically different in every different act; and that what I mean by calling all these different acts mine is either merely that they have some kind of relation to one another or that they all have a common relation to some other entity, external to them, which may or may not be something which deserves to be called "me." On any such view, what I assert to be true of this black mark, when I say that it is seen by me, would not be simply that it is directly apprehended by me, but something more complex in which, besides direct apprehension, some other quite different relation was also involved. I should be asserting both (1) that the black mark is being directly apprehended by something, and (2) that this act of direct apprehension has to something else, external to it, a quite different relation, which is what makes it an act of mine. I do not know how to decide between these views, and that is why I wished to explain that the fundamental relation which I wish to call direct apprehension, is one which quite possibly never holds between me and any sensible. But, once this has been explained, I think no harm can result from using the expression "I directly apprehend A" as a synonym for "A direct apprehension of A occurs in my mind." And in future I shall so speak, because it is much more convenient.

The only other point, which seems to me to need explanation, in order to make it quite clear what the relation I call "direct apprehension" is, concerns its relation to attention; and as to this I must confess I don't feel clear. In every case where it is quite clear to me that I am directly apprehending a given entity, it seems also clear to me that I am, more or less, attending to it; and it seems to me possible that what I mean by "direct apprehension" may be simply identical with what is meant by "attention," in one of the senses in which that word can be used. That it can, at most, only be identical with one of the relations meant by attention seems to me clear, because I certainly can be said to attend, in some sense or other, to entities, which I am not directly apprehending: I may, for instance, think, with attention, of a sensible, which I saw yesterday, and am certainly not seeing now. It is, therefore, clear that to say I am attending to a thing and yet am not directly apprehending it, is not a contradiction in terms: and this fact alone is sufficient to justify the use of the special term "direct apprehension." But whether to say that I am directly apprehending a given thing and yet am not attending to it, in any degree at all, is or is not a contradiction in terms, I admit I don't feel clear.

However that may be, one relation, in which sensibles of all sorts do sometimes stand to our minds, is the relation constituted by the fact that we directly apprehend them: or, to speak more accurately, by the fact that events which consist in their being directly apprehended are in our minds, in the sense in which to say that an event is in our minds means merely that it is a mental act of ours—that it has to our other mental acts that relation (whatever it may be) which we mean by saying that they are all mental acts of the same individual. And it is clear that to say of a sensible that it is directly apprehended by me, is to say of it something quite different from what I say of a mental act of mine, when I say that this mental act is in my mind: for nothing is more certain than that an act of direct apprehension or belief may be in my mind, without being itself directly apprehended by me. If, therefore, by saying that a sensible is in our minds or is ours, we mean merely that it is directly apprehended by us, we must recognise that we are here using the phrases "in our minds" or "ours" in quite a different sense from that in which we use them when we talk of our mental acts being "in our minds" or "ours." And why I say this is because I think that these two relations are very apt to be confused. When, for instance, we say of a given entity that it is "experienced," or when the Germans say that it is "erlebt," it is sometimes meant, I think, merely that it is directly apprehended, but sometimes that it is in my mind, in the sense in which, when I entertain a belief, this act of belief is in my mind.

But (2) it seems to me to be commonly held that sensibles are often in our minds in some sense quite other than that of being directly apprehended by us or that of being thought of by us. This seems to me to be often what is meant when people say that they are "immediately experienced" or are "subjective modifications"; though, of course, both expressions are so ambiguous, that when people say that a given entity is immediately experienced or is a subjective modification, they may mean merely that it is directly apprehended. And since I think this view is held, I want to explain that I see no reason whatever for thinking that sensibles ever are experienced by us in any other sense than that of being directly apprehended by us. Two kinds of argument, I think, are sometimes used to show that they are.

(a) It is a familiar fact that, when, for instance, we are in a room with a ticking clock, we may seem suddenly to become aware of the ticks, whereas, so far as we can tell, we had previously not heard them at all. And it may be urged that in these cases, since the same kind of stimulus was acting on our ears all the time, we must have experienced the same kind of sensible sounds, although we did not directly apprehend them.

But I think most psychologists are now agreed that this argument is quite worthless. There seem to me to be two possible alternatives to the conclusion drawn. It may, I think, possibly be the case that we did directly apprehend the ticks all the time, but that we cannot afterwards remember that we did, because the degree of attention (if any) with which we heard them was so small, that in ordinary life we should say that we did not attend to them at all. But, what, I think, is much more likely is that, though the same stimulus was acting on our ears, it failed to produce any mental effect whatever, because our attention was otherwise engaged.

(b) It is said that sometimes when we suddenly become aware, say, of the eighth stroke of a striking clock, we can remember earlier strokes, although we seem to ourselves not to have directly apprehended them. I cannot say that I have ever noticed this experience in myself, but I have no doubt that it is possible. And people seem inclined to argue that, since we can remember the earlier strokes, we must have experienced them, though we did not directly apprehend them.

But here again, the argument does not seem to me at all conclusive. I should say, again, that it is possible that we did directly apprehend them, but only with a very slight degree of attention (if any). And, as an alternative, I should urge that there is no reason why we should not be able to remember a thing, which we never experienced at all.

I do not know what other arguments can be used to show that we sometimes experience sensibles in a sense quite other than that of directly apprehending them. But I do not know how to show that we do not; and since people whose judgment I respect, seem to hold that we do, I think it is worth while to say something as to what this sense of "experience" can be, in case it does occur.

I have said that sometimes when people say that a given entity is "experienced" they seem to mean that it belongs to some individual, in the sense in which my acts of belief belong to me. To say that sensibles were experienced by me in this sense would, therefore, be to say that they sometimes have to my acts of belief and acts of direct apprehension the same relation which these have to one another—the relation which constitutes them mine. But that sensibles ever have this kind of relation to my mental acts, is a thing which I cannot believe. Those who hold that they are ever experienced at all, in some sense other than that of being directly apprehended, always hold, I think, that, whenever they are directly apprehended by us, they also, at the same time, have to us this other relation as well. And it seems to me pretty clear that when I do directly apprehend a sensible, it does not have to me the same relation which my direct apprehension of it has.

If, therefore, sensibles are ever experienced by us at all, in any sense other than that of being directly apprehended by us, we must, I think, hold that they are so in an entirely new sense, quite different both from that in which to be experienced means to be directly apprehended, and from that in which to be experienced means to occur in some individual's mind. And I can only say that I see no reason to think that they ever are experienced in any such sense. If they are, the fact that they are so is presumably open to the inspection of us all; but I cannot distinguish any such fact as occurring in myself, as I can distinguish the fact that they are directly apprehended. On the other hand, I see no way of showing that they are not experienced in some such sense; and perhaps somebody will be able to point it out to me. I do not wish to assume, therefore, that there is no such sense; and hence, though I am inclined to think that the only sense in which they are experienced is that of being directly apprehended, I shall, in what follows, use the phrase "experienced" to mean either directly apprehended or having to something this supposed different relation, if such a relation there be.