CLARK McCAULEY is professor of sciences and mathematics and co-director of the Solomon Asch Center for Study of Ethnopolitical Conflict at Bryn Mawr College. His research interests include the psychology of group identification, group dynamics and intergroup conflict, and the psychological foundations of ethnic conflict and genocide. McCauley is co-author of the recent book, Friction: How Radicalization Happens to Them and Us, which examines how radicalization can lead to political violence in individuals and groups.