Public Goods Game

The public goods game is the canonical multi-person social dilemma used to study cooperation. Each member of a group is endowed with money and simultaneously decides how much to keep privately and how much to contribute to a common pool; the pool is multiplied and split equally among all members regardless of contribution. Because the marginal per-capita return is less than one but the group return exceeds one, every individual is privately better off free-riding while the group is collectively better off if all contribute -- the defining tension of a social dilemma. Experiments consistently show people contribute well above the self-interested zero, but contributions decay over repeated rounds unless institutions intervene. Fehr and Gachter's influential demonstration that allowing players to pay to punish free-riders restores and sustains high cooperation made the paradigm central to research on norms, altruistic punishment, and collective action.