Repeated interactions provide a prominent but paradoxical hypothesis for human cooperation in one-shot interactions. Intergroup competitions provide a different hypothesis that is intuitively appealing but heterodox. We show that neither mechanism reliably supports the evolution of cooperation...

This paper surveys recent experimental and field evidence on the impact of concerns for fairness, reciprocity and altruism on economic decision making. It also reviews some new theoretical attempts to model the observed behavior.

Most economic models are based on the self-interest hypothesis that assumes that material self-interest exclusively motivates all people. Experimental economists have gathered overwhelming evidence in recent years, however, that systematically refutes the self-interest hypothesis, suggesting...

We show that concerns for fairness may have dramatic consequences for the optimal provision of incentives in a moral hazard context. Incentive contracts that are optimal when there are only selfish actors become inferior when some agents are concerned about fairness. Conversely, contracts that...

In recent years a large number of experimental studies have documented the existence of strong reciprocity among humans. Strong reciprocity means that people willingly repay gifts and punish the violation of cooperation and fairness norms even in anonymous one-shot encounters with genetically...