Steven Pinker's essay on the moral sciences (Adam Smith, anyone?) in the Times is written in the excited tone of a true believer, and I'm a heretic. The claim is that morality is hard-wired into the brain, and that experimental psychology (with its LiteBrite phrenology, the fMRI) is the window into that wiring.
The main problem I have, grosso modo, is lightly touched upon by Pinker about midway through his article where -- in the context of categorizing the moral priorities of various cultures -- he tosses off a brief disclaimer about whether a given anthropologist is a "lumper or a splitter." The implication is that, if one lumps enough, one can find a useful number of moral categories whose distribution can be predicted by presumed psychological laws.
But morality (which Pinker, if you notice, never gets around to defining) is the very art (or science, or discipline-of-thought) of making such distinctions. Recourse to broad generalities of human behavior (that millions of people around the globe tend to respond the same way to a an Internet survey about counterfactual trolley accidents) is not the same thing as discerning the sources - let alone the definition or guiding principle - of morality. That various approved opinions or behaviors are "moralized" (smoking) or "demoralized" (premarital sex) does not mean they are indicators of changing boundaries of morality, merely that high dudgeon is fungible.
Lumping and splitting is particularly tricky when it comes to religion. This is important, because comparative religionists like to lump. I don't know about the details of many religions, but when "the holy ablutions and dietary restrictions of [...] Orthodox Jews" (that 'Orthodox' drives me nuts, but never mind) is taken as an exemplar of the moral categorization "purity," I raise an eyebrow. The same mistake is made here by which Chomsky facilely lumps all languages into the same hard-wired diagram. Which "holy ablutions" are meant exactly? There are a number in the Torah, and they don't all serve the same purpose. The aim of kashrut, in the Biblical worldview, is a vexing question. I think Milgrom has it right with his proposal that the dietary restrictions are a way to separate out the Jewish people in holiness from the nations. But this is a crucial distinction and something different from "purity."
I don't deny that moral psychology is a science that will contribute to our understanding of morality. But definitions, and fine distinctions, make morality a very tangled tissue to see with any scan.