Many things changed on September 11, 2001, and apart from the profound sense of loss, there was also stunned disbelief—a question of “How?”

In the aftermath, Justin Lyon enrolled in a graduate program at MIT, studying system dynamics, or, to put it very simply, how complex things—systems with many moving parts—act and change over time. There, he focused on simulating the growth of radical Islam—that is, predicting likelihoods of violence, insurgencies, and counterinsurgencies in tandem with