Interdependent preferences and endogenous reciprocity

This paper employs an indirect approach to formally examine the evolutionary stability of interdependent preferences when players randomly engage in pairwise interactions. Following the model specification for altruism and spitefulness in experiments proposed by Levine (1998), we also explore the stability of reciprocity and reciprocal preferences. In particular, we study how individuals equipped with intrinsic preferences such as altruism, selfishness or spitefulness adjust their behavior depending on who they interact with. The key aspect of our method is that behavioral preferences are choice variables that optimally evolve, accounting for strategic interaction. Our model predicts that in a specific economic framework characterized by negative externalities and strategic substitutes, there is a continuum of evolutionary stable interdependent preference profiles: At least one player behaves spitefully, and at most one acts selfishly. The emergence of altruism as an evolutionarily stable preference crucially depends on how large the support for preferences is. When players have reciprocal preferences, altruism might arise even in meetings where one player is intrinsically spiteful, but not necessarily from the intrinsically altruistic player.