ABSTRACT
The empirical evidence for the existence of a social norm of reciprocity is overwhelming. The material from evolutionary biology is most relevant to the work on reciprocal altruism. The social psychological literature on self-esteem raises some complications for moral theory. It is by no means clear what the 'optimal level' of self-esteem is, in part because high self-esteem can inhibit the perception of 'negative information', to the detriment of the individual. Laboratory experiments done by social psychologists suggest that behavior in accord with the norm of reciprocity is distinct from 'economic' or rational self-maximizing conduct. Philosophers have mentioned the importance of reciprocity, connecting it to notions of equity, requital, gratitude, fairness and justice. In The Needs of Strangers, Michael argues that if we focus on what humans need, people's will find much of the debate between liberals and socialists to be misplaced.
