Pro-sociality as a Foundation for Intergroup Conflict

Abstract Intergroup conflict can be modeled as a two-level game of strategy, in which pro-sociality can take the form of trust and cooperation within groups or between groups. We review recent work, from our own laboratory and that of others, that show how biological and socio-cultural mechanisms that promote pro-social preferences and beliefs create in-group bounded, parochial cooperation and, sometimes, parochial competition. We show when and how parochial cooperation and competition intensifies rather than mitigates intergroup conflict.