“It is the responsibility of intellectuals to speak the truth and to expose lies.” So declared Noam Chomsky fifty years ago today in his landmark anti–Vietnam War essay “The Responsibility of Intellectuals.” Writing in the pages of the New York Review of Books, Chomsky asserted that intellectuals have a moral duty to use their training and access to information to challenge American imperialism.

The essay’s core argument — that thinkers can best contribute to social change by using their position to tell truths the powerful wish to keep hidden — remains essential for comprehending Chomsky. And the strengths and limitations of Chomsky’s analysis are a valuable starting point for understanding how left-wing intellectuals today can help defeat resurgent right-wing nationalism and revive the socialist movement.