UC San Diego

If war results from disagreement about relative strength, then it ends when opponents learn enough about each other. Learning occurs when information is revealed by strategically manipulable negotiation behavior and non-manipulable battlefield outcomes. I present a model of simultaneous bargaining and fighting where both players can make offers and asymmetric information exists about the distribution of power. In the Markov perfect sequential equilibrium, making and rejecting offers has informational value that outweighs the one provided by the battlefield. However, states use both sources of information to learn and settle before military victory. The Principle of Convergence posits that warfare ceases to be useful when it loses its informational content, and that belief in defeat (victory) is not necessary to terminate (initiate) hostilities. Thus, the standard puzzle in international relations that seeks to account for prewar optimism on both sides may not be that relevant.