Anthropologies

Rob continues my question on God and anthropology.  He looks at the question from the perspective of one who rejects the claimed moral obligation. If there is a Creator and I reject his moral order, then, as Rob suggests, there are temporal consequences (failure to fully develop as a human being) and possibly eternal consequences (damnation).  And, this hold true whether I contest or reject the Creator's morality.  Whether or not there is a Creator, if I reject the moral order imposed by my society, there will be temporal consequences ranging from a cold stare to criminal sanction. 

I want to explore the other side of the equation.  On what basis does a society impose moral obligations on its denizens?  And, how does it arrive at that morality, especially on those issues backed by criminal sanction.   If a given society's public anthropology holds that human beings are all accidents (in other words the idea that our rights are self-evident, given to us by a Creator, finds no purchase in the halls of power), then what is that society's basis for saying that any individual is obligated by that society's moral norms, whether those norms are generated by a dictator or a majority?