A Theory of Endogenous Commitment

Commitment is typically modeled by assigning to one of the players the ability to take an initial binding action. The weakness of this approach is that the fundamental question of who has the opportunity to commit cannot be addressed, as it is assumed. This paper presents a framework in which commitment power arises endogenously from the fundamentals of the model. We construct a \u85nite dynamic game in which players are given the option to change their minds as often as they wish, but pay a switching cost if they do so. We show that for games with two players and two actions there is a unique subgame perfect equilibrium with a simple structure. This equilibrium is independent of the order and timing of moves and robust to other protocol speci\u85cations. Moreover, despite the perfect information nature of the model and the costly switches, strategic delays may arise in equilibrium. The exibility of the model allows us to apply it to various environments. In particular, we study an entry-deterrence situation. Its equilibrium is intuitive and illustrative of how commitment power is endogenously determined.