As moral as we need to be

In response to the idea that morality originated when subordinate members o f groups banded together to constrain more dominant members, I argue that a more general function of morality is to uphold systems of cooperative exch ange ever threatened by the temptation to contribute less than one's share and to take more than one's share. Humans inherit biologically-evolved disp ositions to behave morally, that is to say to uphold systems of cooperation , and to behave immorally, that is to say to exploit the systems of coopera tion from which they benefit. We are as moral as we need to be to reap the benefits of cooperation.