We study infinitely repeated anonymous random matching games played by communities of players, who only observe the outcomes of their own matches. It is well known that cooperation can be sustained in equilibrium for the prisoner's dilemma (PD) through grim trigger strategies. Little is known...

Reputation concerns can discipline agents to take costly effort and generate good outcomes. But what if outcomes are not always observed? We consider a model of reputation with shifting observability, and ask how this affects agents' incentives. We identify a novel and intuitive mechanism by...

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...