"For decades, Ronald Reagan's name has served as shorthand for the entirety of the modern conservative movement. Contrary to conventional wisdom, however, Reaganism was, from today's vantage point, a brief digression in conservatism's history. In the 1980s, an unusual set of economic and political conditions and an unusually charismatic leader combined to win huge majorities for Reagan's vision of American exceptionalism, commitment to small government,...