Argue/debate.. I prefer "discussion". .

Don has a good point though. I would walk away and think about that if I were you .

I think people are obsessed with getting the last word. Not all, but a good chunk. Your advice is what I've been practicing, and it seems to work. Argue to listen, not to counter. Especially in my line of work, when we'e able to discuss possible additions to a game. When someone has an idea, you MUST hear them out. Too many times you hear the SAME person interrupt the person presenting an idea, and he'll pose a problem of a suggestion that is an extremely rare scenario. This often drives the focus elsewhere, and people forget just how rare this issue would be. It really slows the design process down, as Mason stated.

I really hope a lot of people read your advice. It really doesn't just apply to forums.