He said it once. He also said that downvoting for disagreement is a problem - that's why comment scores are no longer shown.

He said it at least 3 times:

http://news.ycombinator.com/item?id=117171 "I think it's ok to use the up and down arrows to express agreement. Obviously the uparrows aren't only for applauding politeness, so it seems reasonable that the downarrows aren't only for booing rudeness."

http://news.ycombinator.com/item?id=392347 "Downvoting has always been used to express disagreement."

http://news.ycombinator.com/item?id=658691 "IIRC we first had this conversation about a month after launch. Downvotes have always been used to express disagreement. Or more precisely, a negative score has: users seem not to downvote something they disagree with if it already has a sufficiently negative score."

I'm not aware of a comment where he said downvoting for disagreement is a problem. I recall comments about gratuitous negativity, and comments about how certain excessively rude comments were getting upvoted when they should be downvoted. But it's possible I'm behind the times on that front.

Thanks for those! I've added them to my list.

I can't cite sources, but the reason comment scores are no longer shown was because having comment scores was getting pg dragged into chest-beating karma competitions, so he hid the scores to have to deal personally with less of that. Having no scores showing prevents the scores from being a way that each "side" on an argument can keep score of "who is winning" so upvotes don't fuel those kinds of ego-based arguments anymore. It was effective in getting him what he wanted, though it was decried by many people for depriving them of information concerning comment quality that they had previously valued.

This is the post I was thinking of:

https://news.ycombinator.com/item?id=1057347

> My plan for dealing with downvoting is just not to display points on comments any more. The hard part is that to make that work, I also have to come up with alternative ways for people to find the comments they're most interested in on big threads.

But as you say there's probably more to it than that. I'll have a noodle around with search later to see if I can find more.

I am really, really terrible at finding things on HN, but I am inclined to remember things about social dynamics. Somewhere, he said something to the effect that he is being dragged into these arguments fueled by upvotes less often, so he feels that comment scores being hidden was successful in getting him what he wanted because he was spending too much time on that, so, no, comment scores are not likely to come back. You might look for some kind of follow up question of the Ask PG variety where people were hoping he would bring them back. It might have been something like that. (/Real hand wavy clues -- enjoy the hunt.)