Sidney Hook (December 20, 1902 – July 12, 1989) was an American philosopher of pragmatism known for his contributions to the philosophy of history, the philosophy of education, political theory, and ethics. After embracing communism in his youth, Hook was later known for his criticisms of totalitarianism, both fascism and Marxism–Leninism. A social democrat, Hook sometimes cooperated with conservatives, particularly in opposing Marxism–Leninism. After World War II, he argued that members of such groups as the Communist Party USA and Leninists like democratic centralists could ethically be barred from holding the offices of public trust because they called for the violent overthrow of democratic governments. Background Sidney Hook was born on December 20, 1902, in Brooklyn, New York City, to Jennie and Isaac Hook, Austrian Jewish immigrants. He became a supporter of the Socialist Party of America during the Debs era when he was in high school. In 1923, he earned a BA at the City College of New York and in 1927 Ph.D. at Columbia University, where he studied under pragmatist philosopher John Dewey. Career In 1926, Hook became a professor of philosophy at New York University and was head of the Department of Philosophy from 1948 to 1969. He retired from the University in 1972. In 1931, Hook began teaching at the New School for Social Research through 1936, after which he taught night school there until the 1960s. By 1933, Hook and New School colleague Horace M. Kallen were serving also on the ACLU's academic freedom committee. Marxist At the beginning of his career, Hook was a prominent expert on Karl Marx's philosophy and was himself a Marxist. He attended the lectures of Karl Korsch in Berlin in 1928 and conducted research at the Marx-Engels Institute in Moscow in the summer of 1929. At first, he wrote enthusiastically about the Soviet Union, and, in 1932, supported the Communist Party's candidate, William Z. Foster, when he ran for President of the United States. However, Hook broke completely with the Comintern in 1933, holding its policies responsible for the triumph of Nazism in Germany. He accused Joseph Stalin of putting "the needs of the Russian state" over the needs of the international revolution. However, Hook remained active in some of the causes of the Marxist left during the Great Depression. In 1933, with James Burnham, Hook was one of the organizers of the American Workers Party, led by the