The modern age is clogged with—or more descriptively, cursed by—political causes. Every such cause trumpets peaceful and progressive virtues but, in practice, each is a turbulence of violence. The worst of them—Communism, Nazism, Islamism—provide the ideological framework for mass murder. With whatever messianic fervor a political cause is promoted, at its core is the defense of some partisan interest, usually religious or national. Purportedly universal causes—pacifism, human rights, ecological issues—have a similar tendency to define themselves as moral absolutes that legitimize aggression. And as that old rake Norman Douglas was the first to point out, somebody will be found to defend even the vilest cause. An English poet, for instance, judged the Khmer Rouge to be merciful because in spite of their poverty they shot their victims rather than clubbing them to death.

A cause offers purpose where previously there might have been none. The divide between Us and Them, between believer and unbeliever, between this nation and that, follows from the overriding psychological motives that great novelists explore, such as ambition and hunger for power, utopianism, vanity, adventure, a sense of superiority—all the various paths to self-righteousness, that most satisfying and all-encompassing of human illusions.

It was not always so. True, for centuries people had fought and died in wars of religion. In the Age of Enlightenment, however, England and France each developed the doctrine of nationalism, whereby subjects of a king were to see themselves instead as citizens of a nation-state. To the rest of