THERE probably aren’t many things that the Islamic State, Jon Stewart and the president of Iraqi Kurdistan agree on, but there is one: the pernicious influence of the Sykes-Picot Agreement, a secret plan for dividing up the Middle East signed by France and Britain, 100 years ago this week. It has become conventional wisdom to argue, as Vice President Joseph R. Biden Jr. recently did, that the Middle East’s problems stem from “artificial lines, creating artificial states made up of totally distinct ethnic, religious, cultural groups.”

That Western imperialism had a malignant influence on the course of Middle Eastern history is without a doubt. But is Sykes-Picot the right target for this ire?

The borders that exist today — the ones the Islamic State claims to be erasing — actually emerged in 1920 and were modified over the following decades. They reflect not any one plan but a series of opportunistic proposals by competing strategists in Paris and London as well as local leaders in the Middle East. For whatever problems those schemes have caused, the alternative ideas for dividing up the region probably weren’t much better. Creating countries out of diverse territories is a violent, imperfect process.