The first forum I joined was one of people who enjoyed ripping on people who said stupid things and who wasted space. I joined there at a pretty young age: I still credit it for teaching me to think about and revise things that I post online. I still remember it fondly, in part because it was a tight community: it scared most people away, but that was good, because it was a site for a niche audience. (Similar, I'd say, to the niche audience that ought to be in Hacker News.)

I've also worked with forums that aimed towards nice: they tended to have a less fanatic userbase, and the people who remained were of wildly varying quality. Nice in excess leads to a downfall.

(I also haven't noticed much unfair hostility until the last month: the election polarized a lot of people, and brought in a lot of attitudes that seem less concerned with new information and interesting articles. Hopefully it will pass.)

I think you've combined two meanings in the word hostility: one is to argue and debate, i.e. antagonistic or Socratic; the other is to be disrespectful and insulting - aggressive domination, to win by making the other lose. The same with nice as its opposite: one meaning is to approve of anything with no objectivity or truth; the other is to respect others. I agree that challenging people is a good thing (even though it can feel uncomfortable and "not nice"), provided it is done is in a respectful way.

I think the key is whether one's goal is to get to the truth and learn and build; or whether one's goal is humiliation to show your superiority. However, it's fraught with danger to evaluate what someone else's goal is, because your interpretation of their intention is necessarily a step distant from the truth about them. But I see many comments on HN that are clearly seem way or the other (the remainder I'm not sure of).

I really love being shown I'm wrong by someone who sees more than I do. For the supernatural sense of expanding one's world, it's second only to experience. :-)

I've always defined hostility in a kind of weird way. For me, it's absolute intolerance to new ideas until a good reason is given for them. Which is to say, if somebody suggests something new, the burden of proof is entirely on them to explain themselves, before I'll consider the idea. In return, I assume everybody else works similarly, and post accordingly. It's a policy that leads to people contributing lots of fleshed-out ideas, and it keeps noise way down.

Of course, by that definition it's possible to be both hostile and polite. I just see hostility as being a slight notch above debate: in debate, there are two well-defined sides that play off each other. On a site where there can be a wide variety of opinions and ideas, the barrier for entry should be set a wee bit higher.

For when you are reading, I guess it keeps your own personal attention uncluttered by noise. It also implies you wouldn't challenge poorly presented ideas, but just ignore them as noise. Interesting.

Yeah, I was mainly thinking hostile as opposed to polite.