Karl Robert Reichsgraf von Nesselrode-Ehreshoven, also known as Charles de Nesselrode was a Russian German diplomat. For forty years (1816–1856) Nesselrode guided Russian policy as foreign minister. He was also a leading European conservative statesman of the Holy Alliance.
Karl Philipp Moritz was a German author, editor and essayist of the Sturm und Drang, late Enlightenment, and classicist periods, influencing early German Romanticism as well. He led a life as a hatter's apprentice, teacher, journalist, literary critic, professor of art and linguistics, and member of both of Berlin's academies.
Sir Karl Raimund Popper was an Austrian-British philosopher, academic and social commentator. One of the 20th century's most influential philosophers of science, Popper is known for his rejection of the classical inductivist views on the scientific method in favour of empirical falsification. According to Popper, a theory in the empirical sciences can never be proven, but it can be falsified, meaning that it can be scrutinised with decisive experiments. Popper was opposed to the classical justificationist account of knowledge, which he replaced with critical rationalism, namely "the first non-justificational philosophy of criticism in the history of philosophy".
Karl Berngardovich Radek was a Russian revolutionary and writer active in the Polish and German social democratic movements before World War I and a Communist International leader in the Soviet Union after the Russian Revolution.
