Christopher Caldwell is not a household name. But for the relatively small set of people who care deeply about political writing, he is a towering figure. His prose — full of wit and irony, enlivened by an eye for paradox and the telling detail, informed by a polyglot and polymathic erudition — is second to none in the world of conservative journalism and exceeds nine-tenths of what is published in the press at large. In a review of Caldwell’s previous book, 2008’s immigration-skeptic Reflections on the Revolution in Europe, the Marxist historian Perry Anderson, himself one of the most learned...