Contestants have to choose whether to initiate a contest or war, or whether to remain peaceful for another period. We find that agents wait and initiate the contest once their rival is sufficiently weak to be an easy target.

We study how norms can solve distributional conflict inside a clan and the efficient coordination of collective action in a conflict with an external enemy. We characterize a fully non-cooperative equilibrium in a finite game in which a self-enforcing norm coordinates the members on efficient...