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....

We motivate this paper with a puzzle. When we asked subjects to give five dollars to charity today, about 30 percent agree, but when the donation would instead be paid in one week, giving increases by 50 percent. The puzzle is that received models of self-control cannot explain this...