- And we wonder what can be that 'philosophy of education' which believes that young people can be trained to the duties of citizenship by wrapping their minds in cotton wool.
- The greatest danger that threatens us is neither heterodox thought nor orthodox thought, but the absence of thought.
- Freedom, Loyalty, Dissent (1954)
- The Bill of Rights was not written to protect governments from trouble. It was written precisely to give the people the constitutional means to cause trouble for governments they no longer trusted.
- Letter to the Editor, in The New York Times (1971).