Sam Harris recently had a talk on TED Talks called "Science can Answer Moral Questions". So what's that old horseman of the apocalypse doing these days, anyway? He's writing a book called "The Moral Landscape: How Science can Determine Human Values". He's devoting a whole book to ending "religion’s monopoly on morality and human values."
If I had just read the title, I might have agreed with Sam Harris. It's not that hard. First we start with some basic principle, like "fed people are better than unfed people", and then we can use science to figure out which actions will ultimately feed more people. Easier said than done, but then no one said ethics was easy.
But Sam Harris got a lot of criticism for his talk, because he argued something much stronger. He thinks that you can use science to decide the basic principle itself. Sam Harris argues for the basic principle that "we should value the wellbeing of humanity". If I ask why, Sam Harris responds that this is a "profound and profoundly stupid question." I think he means that there's no real justification for it, but it's obvious.
As far as I'm concerned, that's basically conceding that it's not science. Science is not in the business of justifying unjustifiable statements, whether they're obvious or not. In any case, wellbeing is only an obvious value as long as you consider extreme cases and are unclear about the details.
But rather than continuing my apocryphal rant on metaethics, let me discuss Sam Harris' motivations.
Popular wisdom says that if God exists, then there is objective morality, and if God doesn't exist, then there isn't. Sam Harris wants to argue that objective morality is possible even without God.
But I would go in the completely opposite direction. You cannot derive "ought" from "is", even if the "is" includes God. If you believe in a benevolent deity, you might claim that values come from God. But why should we just accept these values? Because it's "obvious" (particularly if there is a heaven and hell, since one is obviously more desirable). But not because it's justifiable. Same problem Sam Harris ran into.
Sam Harris' other motivation is that he would like to have objective grounds from which he can condemn burqas and nazis. But does having an objective morality really help?
Imagine that I got in a hypothetical argument with Hitler. There are two possibilities. The first possibility is that Hitler and I agree on enough moral precepts that I could in principle persuade him to stop the Holocaust. The fact that the moral precepts are not objective truths does not matter, because we already agree on them. The second possibility is that we do not agree on enough moral precepts. I daresay that claiming that the moral precepts are objectively true because they're "obvious" would not move Hitler.
In conclusion, Sam Harris is wrong, and for the wrong reasons. You know, I'm not sure when I last agreed with Sam Harris on any major point.