Violent Radicalization in Europe: What We Know and What We Do Not Know

When, why, and how do people living in a democracy become radicalized to the point of being willing to use or directly support the use of terrorist violence against fellow citizens? This question has been at the center of academic and public debate over the past years as terrorist attacks and foiled plots inspired by militant Islamism have grabbed European and American headlines. This article identifies and discusses empirical studies of radicalization and points to the strengths as well as the weaknesses characterizing these studies. The aim is to take stock of the current state of research within this field and to answer the question: From an empirical point of view, what is known and what is not known about radicalization connected to militant Islamism in Europe?