Samuel J. Huntington’s 1993 “The Clash of Civilizations?” is the most assigned article in American political science. It predicts a worldwide culture war (but not the kind you're thinking of). The book became a massive bestseller, Huntington was all over TV and his theory is still talked about all the time. It made him a darling to the press but reviled by his fellow academics. Think of "Clash" as a dark rejoinder to Fukuyama’s already-pretty-morose “End of History.” Instea...