American educator and social philosopher who studied historical theory in relation to American philosophy. He was among the first U.S. scholars to analyze Marxism and was firmly opposed to all forms of totalitarianism, holding liberal democracy as the most viable political structure for social and scientific advancement.

After receiving a doctorate from Columbia University (1927) with John Dewey as his mentor, Hook taught at New York University (1927–69) until he retired to become senior research fellow at the Hoover Institution on War, Revolution, and Peace at Stanford University (1973–89). An exponent of pragmatism, secularism, and rationalism, he advocated a general philosophy of personal development. He wrote and edited more than 35 books including Towards the Understanding of Karl Marx: A Revolutionary Interpretation (1933), The Hero in History (1943), Education for Modern Man (1946; rev. ed. 1963), In Defense of Academic Freedom (1971), and Revolution, Reform, and Social Justice (1975). His autobiography, Out of Step: An Unquiet Life in the 20th Century, was published in 1987.