Tolerance always has limits - it cannot tolerate what is itself actively intolerant.

John Dewey: An Intellectual Portrait 1939. Hook opposed all forms of determinism and argued as William James did that humans play a creative role in constructing the social world and to transforming the natural environment. Later years as anti-Communist
The Great Purge encouraged Hook's increasing ambivalence toward Marxism.

Sidney Hook (December 20 1902 – July 12 1989) was an American philosopher of the Pragmatist school known for his contributions to the philosophy of history the philosophy of education political theory and ethics. A pragmatic social democrat Hook sometimes cooperated with conservatives particularly in opposing Communism.