We study the evolution of both characteristics of reciprocity: the willingness to reward and the willingness to punish. First, both preferences for rewarding and preferences for punishing can survive provided that individuals interact within separate groups. Second, rewarders survive only in...

This paper shows how the fear of signaling distrust can endogenously lead to incomplete contractual agreements. We consider a principal agent relationship where the agent may be trustworthy (dedicated to the project) or not. The principal may trust the agent (i.e. have a high belief of facing a...

We study the evolution of preferences under perfect and almost perfect observability in symmetric 2-player games. We demonstrate that if nature can choose from a sufficiently general preference space, which includes preferences over outcomes that may depend on the opponent's preference-type,...

The separation of the legislative, executive, and judiciary powers is a key principle in most democratic constitutions. We analyze the costs and benefits of separating legislature and executive in an incomplete contracts model: the executive can decide to implement public projects. Under...

We study impersonal exchange and ask how agents can behave honestly in anonymous transactions without contracts. We analyze repeated anonymous random matching games, where agents observe only their own transactions. Little is known about cooperation in this setting beyond the prisoner's dilemma....