Our mental image of a major nation in decline is Britain. And, in retrospect, the British handled their decline pretty gracefully. In just a couple of generations Britain sank from economic and political superpower to second-rank member of a second-rank regional bloc. Yet the transformation happened without much domestic rancor, despite Britain's supposedly bitter class divisions. At worst, the general attitude was a certain sullen resignation. At best, there was a jolly, fatalistic insouciance. The Brits almost seemed to enjoy their ride down.
America will not be so lucky. In David Duke, we have seen the face of American decline. Of...