How Do Terrorist Cells Self-Assemble: Insights from an Agent-Based Model of Radicalization

Abstract

Since the 9/11 attacks, there has been a steady increase in the incidence of self-starter terrorist plots in both Western Europe and the United States. Past studies of self-starter terrorism focused on how persons come to acquire radical beliefs but take the additional step for granted - the transformation of isolated radical individuals into cells or networks that produce violent collective action. To better understand this search and assembly aspect of radicalization we constructed an agent-based computational model of radicalization and then validated its predictions with empirical data. Our work yielded three distinct contributions: 1) we operationalized radicalization with precise network measures and distinguished between four types of radicalization scenarios; 2) we characterized the factors that contribute to radicalization as well as deradicalization; 3) we extended radicalization theory by identifying specific network mechanisms such as occlusion, encapsulation, and magnet-rewiring by which radicals self-organize. Our findings may allow us to distinguish the conditions that lead to small transient cells from conditions that lead to large long-lasting terrorist organizations.