Behind my reciprocation of a friend's gift may lie both instrumental reasons (I expect further future gifts) and communicative reasons (I want to establish or confirm a friendship per se ). In a theory of rational individual action, such communicative reasons can be incorporated as an argument...

This paper addresses the question of whether our evolutionary history suggests that humans are likely to be individually selected selfish maximizers or group selected altruists. It surveys models from the literature of evolutionary biology in which groups are formed and dissolved and where the...