Institutions, assortative matching and cultural evolution

This paper studies the role of institution in a Darwinian evolutionary process of cultural selec-tion. The primary function of an institution is to determine how citizens in a society are matched pairwisely to interact. We examine three different types of institutions: utilitarian, egalitarian, and Nash. Two cultural types stand out in the long run through the evolutionary process. The opportunistic cultural type maximizes individual payoff against another opportunistic cultural type, while the civic-minded cultural type maximizes the total payoff of a pair. We show that the structure of the underlying interactions among citizens plays a critical role. On the one hand, the evolutionary stability of the civic-minded cultural type requires supermodularity of the citizens' payoff function under the utilitarian institution and log-supermodularity in addition under the Nash institution. On the other hand, the evolutionary stability of the opportunistic cultural type requires submodularity of the citizens' payoff function under the utilitarian institution and log-submodularity under the Nash institution. Neither type's evolutionary stability is guaranteed under the egalitarian institution.