The Moral Landscape , by Sam Harris has now been out long enough to attract some reviews. Here's a disclaimer - I haven't yet read the book (although I did go and buy a copy, which is calling to me from the shelf over to my left), so I can't comment much on the reviews. Not much.
Here's Kwame Anthony Appiah in The New York Times.
A review by Troy Jollimore for Barnes and Noble.
And a review by John Horgan in Scientific American.
All three make some points that sound plausible, based on what I know of the views that Harris has been expressing. But I'll need to read the book for myself. Horgan makes a point that struck Jerry Coyne as silly - and I agree with Jerry on this. You can't argue, as Horgan more or less does: lots of scientists have acted in ways that we all now regard as immoral; therefore questions of morality cannot be scientific questions (or questions with scientific answers). Surely Harris is not arguing that the actual scientists of any particular era are moral exemplars. He is saying something like the following:
P1. All questions about morality are questions about what actions make sentient beings happy.
P2. All questions about what actions make sentient beings happy are empirical questions.
P3. All empirical questions are open to study by science and have scientific answers.
C. All questions about morality are open to study by science and have scientific answers.
This is a valid argument, so it is sound and leads to a correct conclusion as long as its premises are true. Premises P1. through to P3. are pretty damn controversial, and I doubt that P1. is true without qualification even if the others are, but you can't dismiss the argument simply by claiming that various actual scientists have acted immorally. You need to explain which premise is false, and why.
Even if it's true that all ethical questions have scientific answers, it doesn't follow that the scientists concerned had those answers (or that anyone yet has those answers). Even if the scientists concerned did have the answers - which is vanishingly unlikely - it's not obvious that they'd have understood their application in specific circumstances or that they'd be motivated to apply the answers to their own circumstances. Note that if the Harris sort of argument goes through - or rather, if its premises are true - this tends to imply a theory in which morality is not the sort of thing that intrinsically motivates people. Horgan can't help himself to the absurd idea that "All questions about morality have scientific answers" entails the plainly false and absurd "All scientists are morally exemplary" or "All scientific theories, once believed, have morally good consequences."
So, I put no weight on this line of argument from Horgan. But I do fear that Harris ends up begging some of the most important questions about what morality really is. We shall see: I'll comment on the book here, when I've read it, and I'll be writing a more substantial review for The Journal of Evolution and Technology.