[PHI 3800] Can science answer moral questions?

Some philosophers accept some sort of fact/value distinction, which is often said to have originated in Hume's claim that an 'ought' cannot be derived from an 'is'.

According to the fact/value distinction, factual statements about the world are different from value statements about what is good/bad, moral/immoral, just/unjust, etc. And the latter cannot be deduced in any straightforward way from the former.

Now, recently, Sam Harris has argued against the fact/value distinction. For Harris, values are simply one kind of facts: they are facts about the well-being of sentient creatures.

Since it is often thought that science deals with facts and must remain silent about value questions, Harris rejects the fact/value distinction in order to argue that science can answer moral question. His overall argument seems to go something like this:

1. Moral questions are questions about the well-being of sentient creatures.
2. Science can answer questions about the well-being of sentient creatures.
3. (Therefore) Science can answer moral questions.

Philosophers in general didn't like Harris' argument (to say the least). What do you make of it?