“He would have kept my house for himself if it wasn’t for the Taliban. They were quick and fair.” Thus did a resident of Kandahar, Afghanistan, recently describe Taliban justice to the New York Times. Such words sound jarring to Western ears. Taliban courts may be called quick and brutal in Western accounts, but never quick and “fair.” Yet this observation provides some explanation for the emergence and staying power of extremist movements, from Afghanistan to the Middle East to Nigeria….