A half-century ago, the ideology of the American political establishment was liberal—the New Deal was still new and big government was getting bigger. Today, after a political revolution that began with Barry Goldwater and Ronald Reagan, it may be argued that conservativism has become the dominant ideological force in American politics. But what does conservativism mean today? And if it is ascendant, how long can it remain so? Peter Robinson speaks with Clark S. Judge and John Micklethwait.