I think he's way overconfident in assuming that everyone is or has to be concerned with the "well-being of conscious creatures." Some people do not think that the suffering of all conscious creatures counts, morally. Some people think that suffering ennobles. Some people think that there is such a thing as just punishment (not to prevent further suffering, but purely as retribution.) You're not going to prove those people wrong with science!
On the other hand, there are areas of broad agreement, especially within a society. Usually it's enough to say "But that will cause thousands of deaths!" or "But that leads to lifelong psychological trauma!" or "But that will destroy the economy!" It's so common to assume that death and poverty are bad, that objective facts can usually advance moral discussions. But those assumptions are not universal. Sam Harris can't persuade the Taliban that women are worth caring about. All he can do is to persuade the rest of us not to tolerate the Taliban.
There's a certain unity -- not universal unity, but broad unity -- in what people value. Sociopaths do not have empathy, but most people do. There's even more unity in the common values of modern industrialized democracies. But there are correspondingly more dissenters -- people who could not be persuaded to be concerned for women or children or the families of murderers. Science can tell us a lot about the consequences of actions; it doesn't tell us if we should care about the consequences.
I think that Sam Harris is actually advocating for more confidence on the part of those of us who care about the "well-being of conscious creatures." He's broadly a humanist; he doesn't like unnecessary suffering, and he thinks that the suffering or joy of any conscious creature counts. I have the same views. But you can't prove those views are worth having. At best you can say, empirically, that they're pretty common. You can say that the direction of history moves towards recognizing those views more and more fully.
Sam Harris can't persuade the Taliban that women are worth caring about. All he can do is to persuade the rest of us not to tolerate the Taliban.
I dunno, if the Taliban magically became convinced of the "objective fact" that their god didn't exist, I suspect that they'd be more willing to listen to arguments about the value of girls' schools and such. If there really were an evil bastard deity out there sending people to hell for not following the rules that the Taliban imposes, then, well, it would be better to force women to wear burqas and keep them out of school than let them end up as yet another victim of said evil deity.
Sam Harris has a new book, The Moral Landscape, in which he makes a very simple argument, at least when you express it in the terms we tend to use on LW: he says that a reasonable definition of moral behavior can (theoretically) be derived from our utility functions. Essentially, he's promoting the idea of coherent extrapolated volition, but without all the talk of strong AI.
He also argues that, while there are all sorts of tricky corner cases where we disagree about what we want, those are less common than they seem. Human utility functions are actually pretty similar; the disagreements seem bigger because we think about them more. When France passes laws against wearing a burqa in public, it's news. When people form an orderly line at the grocery store, nobody notices how neatly our goals and behavior have aligned. No newspaper will publish headlines about how many people are enjoying the pleasant weather. We take it for granted that human utility functions mostly agree with each other.
What surprises me, though, is how much flak Sam Harris has drawn for just saying this. There are people who say that there can not, in principle, be any right answer to moral questions. There are heavily religious people who say that there's only one right answer to moral questions, and it's all laid out in their holy book of choice. What I haven't heard, yet, are any well-reasoned objections that address what Harris is actually saying.
So, what do you think? I'll post some links so you can see what the author himself says about it:
"The Science of Good and Evil": An article arguing briefly for the book's main thesis.
Frequently asked questions: Definitely helps clarify some things.
TED talk about his book: I think he devotes most of this talk to telling us what he's not claiming.