It's a hard problem. One of Hacker News's greatest strengths is that no one can downvote submissions. That will result in every story getting a fair chance at the front page (no bury brigades). However, any general topic that people find sufficiently interesting will get upvoted. And -technically-, stuff like this isn't offtopic. We're hackers, and we find it interesting. But this thread isn't really hacker related.
The only counterbalance to this right now is admins killing topics. Doing that after a story has generated a lively discussion like this one might cause users to revolt.
It's easy to get a big response about any topic people feel strongly about. I don't think there's anything hard about killing this thread. I really wish I could. Purely political and religious threads must be banned or this site will quickly begin to suck. These topics are simply too divisive. They will pollute the entire site.
Who cares about a "user revolt"? This site has a focus and that's what makes it great. Those people can discuss this stuff a million other places. There's only one place for hacker news.
Users have rights. If the community decides something they've done is bad, they can't get mad. If one person in the sky that they can't see decides they've done something bad, oh boy will they get mad. And they'll take anyone attached to that thread with them. You thought there was a lot of drama when it came to public attention that editors edit titles? Just wait until they start killing topics that have generated 30+ comments. And any drama that comes from that (topics like "omg goodbye 2 u hackr news i are leaving") can't be killed otherwise it would look like blatant censorship and would make even more people mad.
A counterbalance to this sort of thing that works is a community action, not an admin action.
A one way to implement the community action is to add downarrows. But when someone downvotes a story, the story karma is unaffected. It's only when the story has more downvotes than upvotes that the editors get the option to kill that topic. So that way, the community has decided something is offtopic, but the editor still uses his good judgment about killing a story. I don't see how users could get upset under that sort of arrangement.
I don't see the problem. We all have broad interests. Hackers do things other than hack. If a discussion doesn't interest you, don't participate. You say that politics will pollute the site but you give nothing to back this up. Certainly there is a big difference between day to day USA politics and questions about optimal governance. One is explicitly off-topic and the other isn't.
Of course the politics discussion is going to be lower quality than the startup discussion. We have practical experience with startups. That doesn't mean it isn't worthwhile to discuss things other than hacking and startups.
Social news has been around for two years. Giving one example doesn't mean a whole lot, especially when the community of reddit is fundamentally different from the community of news.ycombinator. The editors of reddit believe in non-intervention. The editors of news.yc believe in active and regular intervention, which means that news.yc won't turn into reddit.
The discussion in this thread isn't anywhere close to what you see on reddit. We have a problem when discussions start actually polluting the site. But they haven't yet, so I don't understand what the problem is.
We need to consider exactly what we don't want to allow on this site. See my new thread.
As staunch implies, a good approach is to keep the general nebulous statement about what we do want, but then be pretty specific about what we don't want.
The only counterbalance to this right now is admins killing topics. Doing that after a story has generated a lively discussion like this one might cause users to revolt.