In the 1960s, Hofstadter saw paranoia as a pernicious and growing influence in American life, citing the rise of groups like the anticommunist John Birch Society. He laid out a blueprint for the paranoid style that, even after all these years, sounds familiar to anyone who ever watched Glenn Beck sweat onto his chalkboard.

And while those furies sometimes ebb, they also sometimes flow. In a November 1963 lecture that formed the basis of a Harper’s cover story and of a book, the Columbia historian Richard Hofstadter defined what he called “the paranoid style in American politics,” a recurring popular tendency to adhere to extreme conspiratorial theories about threats