I'm with Carroll here; I'm also with you, in the sense that I think there are areas of pretty broad agreement on the moral basics, where questions of fact become very relevant.

One thing I wonder about sometimes is what to do about people who have a pretty alien moral system -- but not completely alien. Fundamentalist Christians, for example. Or people in Asian or African societies where they place a higher value on tradition than on freedom.

Are these people "wrong"? That's a lot of people to place outside the pale of reasonable discussion. There are a lot of non-humanists out there -- at least, to some degree or another. On the other hand, if they start to make things morally worse, by my lights -- if they drive gay teenagers to suicide or cut off girls' clitorises -- then I'm not going to say "meh, to each his own." I don't think we have to let just anything stand unchallenged, in the name of tolerance. On the other hand, if we don't have some notion of tolerance of disagreement, we could become pretty dogmatic and dangerous. I do not want to live in a world where some measure of happiness was maximized ruthlessly without my say-so.