In the wake of the Paris, Beirut, and San Bernardino terrorist attacks, fears over "homegrown terrorism" have surfaced to a degree not seen since September 11, 2001--especially following the news that all of the perpetrators in Paris were European citizens. A sought-after commentator in France and a widely respected international scholar of radical Islam, Farhad Khosrokhavar has spent years studying the path towards radicalization, focusing particularly...