Stop showing people other people's comment scores. They stimulate argumentative comments.
I do like that idea. I think I tried it a while ago, but users complained that without comment scores it was too hard to figure out what were the most interesting comments in a thread. Is there some other way to show what the most interesting comments in a thread are? How about if I displayed the point totals for subtrees, but not for individual leaves? Would it solve the problem if you could follow other users, and…
Have you thought at all about discerning between vote value based on some metric? You'd need something that doesn't disproportionately disadvantage new users.