This is a very interesting question: when does a community become an echo chamber? To use the hunting example: I imagine sometimes the hunters talk about stuff to do with hunting itself; the merits of different rifles, or where to find game, or whatever. And this is a reasonable community discussion for them to have, and it wouldn't help to have activists shouting "hunting is evil" over conversations such as that.

But sometimes the hunters will talk about the politics of hunting: one will say, "those activists are wrong to complain about animals suffering, because <reasons here>", and then another will say "yes, it's so obvious they're wrong, because <reasons> are so obviously right", and the echo chamber is ringing - this is the situation where people ideally would be brought into contact with the opposing view.

Can an online community promote the first type of conversation while challenging the other? How would we set about that?

That's the job of good moderation I think.

Perhaps. But I think it would take a particularly far-sighted and philosophical moderator to down-vote/remove a perfectly civil post whose message he agreed with, _just_ because it was contributing to an echo-chamber effect.

I would think this could be accomplished with just a policy to never, ever discuss the politics of the community's niche, and to remove posts that do.

The problem isn't the occasional disagreement, it's when communities raid each other, since people are much more brazen online than in person. In person, thousands of atheists would never march into a church during mass and start berating members for their beliefs, but that's very common in unmoderated communities. Moderation solves this issue when you can shard your communities (see reddit), but Twitter is just a global blob. Whose going to moderate it?

"communities raid each other"

I love that image and it makes a clear picture for me. Playing on a PvP server of WoW before any expansions there was no formal PvP game. What spontaneously happened though was the raiding and taking over of the other factions town. Making a mess and disrupting otherwise normal play until everyone got tired and went to sleep.

It feels so much more intense (real?) in the social media world though.

I think because it takes so little effort. Even in an MMO, you have to man your character to do anything. On twitter all it takes it for at least one person to be tweeting at a given moment to ruin the other community.

Plus, people on WoW would be paying a subscription, people are much more risk averse when they pay. Social media is free, and there's little to lose for most people.

Back in the times of the meow wars ( http://xahlee.info/Netiquette_dir/_/meow_wars.html ) people were at least aware of exactly what they were doing...

Better for whom? I think that's condescending. People already know that some forums only contain like-minded people - that's the point! Connecting with like-minded people about some specialized interest is one of the great advantages of the Internet. You can get valuable things out of it, without being under any illusion that you're talking with a diverse crowd.

Maybe the issue is that we don't have enough forums for people who want to have that debate? A "hunting versus animal rights" forum, for example. You'd need really good moderators, though. Lots of people wouldn't be interested in participating, but sometimes there might be interesting posts to reshare.

If the average person is completely shielded from any kind of discourse surrounding their beliefs, society will suffer. Echo chambers are the main reason politics in the US have become a complete disaster. When you hear the other side's point of view presented by your side, it's going to be biased and will just reinforce your own beliefs.

As evidence of this, think of how many people think that $other_party wants to "destroy America" in some form. Cue (and possibly queue) commenters saying "but $x really does want that!"

I've found that people who claim to know the other side's motivations are projecting for the most part. I catch myself doing it too. Being more aware of bias does not make one less susceptible to it, unfortunately. If anything, it tends to bring overconfidence regarding it :/

I've realized that Americans are uniquely patriotic, but to wildly different countries whose only common trait are their borders.