To understand the "pure" incentives of altruism, economic laboratory research on humans almost always forbids communication between subjects. In reality, however, altruism usually requires interaction between givers and receivers, which clearly must influence choices. Charities, for example,...

If social institutions, like fundraising, create incentives that generate utility from deciding to give, then some donors would decline a request to give to charity now while agreeing now to give later. This meets the classic definition of time-inconsistent choices. This is not because of a...

We report experimental results for a twice-played prisoners' dilemma in which the players can choose the allocation of the stakes across the two periods. Our point of departure is the assumption that some (but not all) people are principled to "do the right thing," or cooperate, as long as their...

This paper compares two methods to encourage socially optimal provision of a public good. We compare the efficacy of vigilante justice, as represented by peer-to-peer punishment, to delegated policing, as represented by the "hired gun" mechanism, to deter free riding and improve group welfare....