Where does our sense of right and wrong come from? Most people think it is a gift from God, who revealed His laws and elevates us with His love. A smaller number think that we figure the rules out for ourselves, using our capacity to reason and choosing a philosophical system to live by.

Moral naturalists, on the other hand, believe that we have moral sentiments that have emerged from a long history of relationships. To learn about morality, you don’t rely upon revelation or metaphysics; you observe people as they live.

All emphasis mine. Via Op-Ed Columnist - The Moral Naturalists - NYTimes.com.

I have to say I am highly sympathetic to that view. So was Adam Smith, as noted by the guys as Cafe Hayek:

It’s worth noting that Adam Smith arrived at the same conclusion 251 years ago. In The Theory of Moral Sentiments (1759), this brilliant scholar – who, in 1776, published an even more influential book – wrote that “Our continual observations upon the conduct of others insensibly lead us to form to ourselves certain general rules concerning what is fit and proper either to be done or to be avoided.”

Just as workable economic arrangements are not, and cannot be, designed and imposed by a higher power, so too, Smith explained, workable morality itself is the product not of any grand design but of the everyday actions, reactions, observations, and practical assessments of ordinary people going about their daily business.

Via The Origins of Moral Sentiments.