Bargaining, interdependence, and the rationality of fair division

We consider two-person bargaining games with interdependent preferences and bilateral incomplete information. We show that in both the ultimatum game and the two-stage alternating-offers game, our equilibrium predictions are consistent with a number of robust experimental regularities that falsify the standard game-theoretic model: occurrence of disagreements, disadvantageous counteroffers, and outcomes that come close to the equal split of the pie. In the context of infinitehorizon bargaining, the implications of the model pertaining to fair outcomes are even stronger. In particular, the Coase property in our case generates “almost” 50-50 splits of the pie, almost immediately. The present approach thus provides a positive theory for the frequently encountered phenomenon of the 50-50 division of the gains from trade.