Known trolls aren't ignored by the hive mind, they're repeatedly dogpiled by a bunch of different people, some of whom react emotionally and some of whom do not.
I believe I know what you're talking about And it's too disorganized, emotional, and over all directed *against* the troll rather than in support of the troll's target(s) to constitute what I'm proposing.
I can think of a couple of posts today that'd fit with what I'm talking about... but always one-offs part of a larger dogpile.
and yet those very same people end up as perfect trollbait and respond, like lemmings, to those very same trolls.
Underlying why support is just as important - if not more so - than engaging the troll.
I should have been more specific about what I mean by "support". It is definitely not a message addressed to the troll. (Confused poster, belligerent poster, whatever) but one directed toward a troll's target. (Person responding to the confused poster, belligerent poster, whatever.) And the support doesn't even need to be public. A PM with "Don't worry about it. You're right, the guy is just a troll." would suffice.
The more err... "judgmental" a comment the more likely it should be private rather than public. But ideally, in my scheme, you'd have a small group of posters opine in various ways that there's no need to engage further with the troll. (Ex: "I think you're right about X but you can't convince Bill Huggins. Just move on.")
That's the "defense". The "Offensive" difference between what I'm talking about and the usual dogpile is that I suggest people point out when a troll (confused... etc.) has misunderstood, ignored, distorted, whatever, another person's posts a LOT more often. And build off each other's posts more often.
Basically, rather than half a dozen people separately fencing with a troll make it half a dozen people collectively engaging, then dismissing, a troll. Don't just keep feeding the troll: Hold up the stuff it's spit out and shove it back down it's throat.
All this, btw, is not something I suggest the mods try to impose from the top down, or do themselves. I think the "common" posters should have each other's back more often. Not all going after the same trolls but amplifying worthwhile posts, and being more willing to acknowledge ones we agree with *in place of* going after ones we don't like.
So rather than the troll getting a bunch of people arguing with him he gets one... and a bunch of people telling *that guy* he's right. Some trolls might be quite happy with that. I hesitate to make a claim about troll psychology, but I think such trolls to be rare. (And if all we're dealing with is a poster whose problem does not involve the intent to sabotage the forum it's a lot easier to deal with.)
EDIT: I think this would work, I think we should try it, and it seemed to more or less work elsewhere, but I don't mean to present this as anything other than a (relatively) casual suggestion. I've tried to explain why I don't think Dach's counter arguments are compelling, for example, but they may be 100% correct for all I know.