Nationalist sentiment has played a pivotal role in uprisings throughout history, from eastern Europe to the United States to Africa. In the Arab world, nationalism has played less of a role. Attempts at a pan-Arab movement fell apart while nationalism evolved over the years into Islamism. But recent uprisings in the Middle East aren't springing entirely from any of the three. So, which "ism" is inspiring revolution in Egypt, Tunisia, Libya and the Gulf? Aviel Roshwald is a professor of history at Georgetown University.