Nearly a century after it first emerged in Egypt, political Islam is redefining the Muslim world. Also called Islamism, this potent ideology holds that the billion-strong global Muslim community would be free and great if only it were pious—that is, if Muslims lived under state-enforced Islamic law, or sharia, as they have done for most of Islamic history. Islamists have long been confronted by Muslims who reject sharia and by non-Muslims who try to get them to reject it. At times benign and at times violent, these confrontations have fueled the revolutions in Egypt in 1952 and Iran in 1979, the al Qaeda attacks in 2001, the Arab Spring of 2011, and the rise of radical Islamist groups such as the self-proclaimed Islamic State (also known as ISIS).
It is not Islam the religion that is generating discord. Rather, the problem is a deep disagreement among Muslims over the degree to which Islam ought to shape the laws and institutions of society. Most Muslims, Islamist or otherwise, are, of course, not jihadists or revolutionaries. But the ongoing competition over what constitutes good public order has polarized them, creating vicious enmities that resist compromise. The result is a self-tightening knot of problems in which each aggravates the others.
Western scholars and policymakers have long struggled to understand the nature of this conflict, but so far, their efforts have fallen short. Although experts on Islamic jurisprudence, theology, and history have produced rich scholarship on Islamism, they have tended to treat it as if it were unique. What they forget is that Islamism is not only Islamic but also an “ism”—an ideology and a plan for ordering common life that should be analyzed alongside other ideologies. No part of the world has generated as many isms as the West itself, and so to aid clear thinking about the contemporary Middle East, it is useful to look back at the West’s own history of ideological strife.
Parts of the Muslim world today, in fact, bear an