Dutch-born pacifist minister A.J. Muste. Hook also debated the meaning of Marxism with radical Max Eastman in a series of public exchanges. Eastman, like Hook, had studied under John Dewey at Columbia University. In the late 1930s, Hook assisted Leon Trotsky in his efforts to clear his name in a special Commission of Inquiry headed by Dewey, which investigated charges made against Trotsky during the Moscow Trials. Anti-Communist The Great Purge encouraged Hook's increasing ambivalence toward Marxism. In 1939, Hook formed the Committee for Cultural Freedom, a short-lived organization that set the stage for his postwar politics by opposing "totalitarianism" on the left and right. By the Cold War, Hook had become a prominent anti-Communist, although he continued to consider himself both a democratic socialist and a secular humanist throughout his life. He was, therefore, an anti-Communist socialist. In 1973, he was one of the signers of the Humanist Manifesto II. In the late 1940s and early 1950s, Hook helped found Americans for Intellectual Freedom, the Congress for Cultural Freedom (CCF), and the American Committee for Cultural Freedom. These bodies—of which the CCF was most central—were funded in part by the Central Intelligence Agency through a variety of fronts and sought to dissuade American leftists from continuing to advocate cooperation with the Soviet Union as some had previously. Hook later wrote in his memoirs that he, "like almost everyone else," had heard that "the CIA was making some contribution to the financing of the Congress." On February 6, 1953, Hook discussed "The Threat to Academic Freedom" with Victor Riesel and others in the evening on WEVD radio (a Socialist radio station whose call letters referred to SPA founder Eugene V. Debs). In May 1953, the John Day Company published Heresy, Yes–Conspiracy, No, a 283-page book expanded from a 1952 pamphlet (Heresy, Yes–Conspiracy, No!), itself expanded from a 1950 New York Times article called "Heresy, Yes–But Conspiracy, No." In the 1960s, Hook was a frequent critic of the New Left. He was opposed to a unilateral withdrawal of U.S. forces from the Vietnam War and defended California Governor Ronald Reagan's removal of Angela Davis from her professorship at UCLA because of her leadership role in the Communist Party USA. Hook was elected a fellow of the American Academy of Arts and Sciences in 1965 and ended his career in the 1970s and 1980s as a fellow of the conservative Hoover Institution