One of the ironies of the post-Cold War world, in which the power of the United States is without rival, is that the costs of isolationism and ignorance are greater than ever. The temptation to imagine that the rest of the world matters less than before is enticing, as America basks in the triumphant glow of a world in which capitalism and democracy, under the aegis of American leadership, are thought to have vanquished all rivals. Although it...