Fairness, Commitment, and Inequality

Abstract

Conditional cooperation is a prominent explanation of reciprocal cooperation in repeated exchange. However, empirical evidence for commitment behavior indicates that people tend to build long-term cooperative relationships characterized by largely unconditional cooperation. Using an agent-based ecological model, earlier work showed that in competitive environments commitment can be a more successful strategy than fair reciprocity. We move further in two respects. First, we add the possibility of randomly mutating strategies under evolutionary pressures. Our results show the lack of evolutionary stable strategies but we also find that commitment strategies still outperform fairness strategies on average. Our second extension introduces inequality in individual capabilities. We find that inequality shifts the balance from commitment towards fairness strategies. Our explanation is that under inequality, strategies benefit from changing interaction partners from time to time because this gives more agents access to strong partners.