One of the most controversial figures in the history of American philosophy, Sidney Hook was "an intellectual street fighter" and "probably the greatest polemicist" of the twentieth century (Edward Shils). Widely known as a Cold War liberal and an intellectual progenitor of neoconservativism, Hook began life as a feisty radical. This now-classic intellectual biography reconstructs Hook's youthful project of fusing American pragmatism and Marxism to create a distinctive approach to philosophy and a politics of revolutionary democratic socialism, carefully charting his interaction with intellectuals such as John Dewey and Max Eastman and his relationship to the Socialist Party, the Communist Party, the American Workers Party, and other political currents.