[vorpalhex]

HN generally sets the expectations that downvotes are only for off-topic or non-helpful posts. Someone disagreeing productively should get your upvote - even if you still disagree with them.

Subreddits often become a way for mods to push their agenda. There are exceptions to this - /r/moderatepolitics has done a decent job of becoming a good place for across-the-aisle discussion, etc. Unfortunately even productive subreddits get raided by crazy people and extremists from time to time.

HN by not having scores (visible to anyone but you) prevents the "playing for internet points" game. As a user you have very little history and exposure to others so each argument is generally standalone. Whereas on reddit someone will dig through my comment history and bring up the subreddits I'm on ("Oh, you claim to be a moderate so you're really just a nazi!") or stalk me, that kind of bad behavior is just not possible on something like HN.

[ghaff]

You do still get a degree of downvoting for unpopular opinions even if they're made in a calm, reasoned manner. But I agree in general. You have mostly relatively mature, rational participants and, someone has to have something of a positive track record before they can downvote. Plus there is a degree of active moderation. None of these individually is a silver bullet but the combination works better than most places.

[0xffff2]

Reddit used to set that expectation too. I think HN's restriction of the downvote button to relatively high-karma users has a much bigger impact than (or at least in combination with) the cultural expectation.