A Bargaining Theory of Conflict with Endogenous Preferences∗

Bargaining models play a central role in International Relations, particularly in the study of conflict. A common criticism of this approach is that it takes the preferences of the actors as fixed. We augment a standard bargaining model by allowing actors ’ preferences over con-flict to diverge from the “objective ” payoffs typical to such a game. Preferences are subject to evolutionary forces, where those who get high objective payoffs reproduce faster. In par-ticular, we apply an indirect evolutionary approach to a canonical bargaining model. We find (1) there is a tradeoff where being “irrationally ” tough leads to better bargains but also more inefficient conflict (2) individuals develop behavioral biases consistent with laboratory results, and (3) these behavioral biases inevitably lead to conflict. Our results shed new light on major questions such as how leader personalities affect foreign policy, why some conflicts appear intractable, and how to interpret the purported decline of violence over recent human history