Who is David Brooks? I've read the bio that I just linked to, but it doesn't say much about a background in philosophy or psychology, which is what he writes about today. His article is a bit of a mess. Let me count some of the ways.
1. "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."
Can this be true? Would most Asians say this, for instance? Perhaps by "people" he means Americans, and then it might be true that most think our sense of right and wrong comes from God. The stuff about God revealing His laws and elevating us with His love sounds like an aside of praise, but is perhaps meant to indicate how God gives us a sense of right and wrong: he reveals laws and loves us enough to raise us to the level of moral agents. This is very obscure though. The laws in the Bible are laws, not a sense of anything. Only those with a sense of right and wrong are capable of caring about them (qua moral laws, and not as practical guides for the self-interested who want to avoid hellfire). The laws don't create this sense. How God's love would do so is a mystery, and wouldn't you expect a believer to say that our knowledge of good and evil comes from the fall? I suppose that depends on how you translate and interpret Genesis.
2. "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."
The relation between reason and choice is obscure here, but I think it has to mean we first choose a system arbitrarily and then reason within it. Does anyone believe this?
3. "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."
If this emergence was a gift from God, then moral naturalists are on the same hand as "most people." If reason and choice were parts of the long history of relationships then moral naturalists seem not so different from the "smaller number of people."
Is "metaphysics" supposed to refer to the reason and choice combo? Odd.
And while it is surely true that we have moral sentiments, it does not follow that to learn about morality you observe people as they live. Except in the sense that you can see what people's morals are by seeing how they live, but we don't need psychologists to tell us that. You don't learn what is actually right or wrong by seeing what people do.
There is an awful lot of confusion here and I can't tell from Brooks' piece whether this is all his fault (some of it surely is) or whether it is there in the work of some or all of the moral naturalists that he cites. Perhaps they are spewing confusion and he has captured it perfectly in his finely ambiguous prose. If you want to spark debate it's probably best not to be too clear after all.