Social norms and the evolution of conditional cooperation

This paper develops a model of social norms and cooperation in large societies. Within this framework we use an indirect evolutionary approach to study the endogenous formation of preferences and the coevolution of norm compliance. Thereby we link the multiplicity of equilibria, which emerges in the presence of social norms, to the evolutionary analysis: Individuals face situations where many others cooperate as well as situations where a majority free-rides. The evolutionary adaptation to such heterogenous environments will favor conditional cooperators, who condition their pro-social behavior on the others' cooperation. As conditional cooperators react flexibly to their social environment, they dominate free-riders as well as unconditional cooperators.