For instance, I’ve read cases where I would have endorsed permanently shuting down the corporation as a remedy. Right or wrong, I would not have even made it through jury selection to participate in the above cited study. Nader couldn’t get on any jury in this country I bet, yet millions respect his work.

I would tend to fall back on my general faith in people and guess that most of us can spot and resist real wackos. The real danger is in a mass of slightly off-center people self-reinforcing out into the weeds because of a lack of diversity inputs to the system.

Of course, my own experience posting on the Posner blog leads me to notice that many people there DO consider me a real wacko. If am accustomed to being considered left of everyone I know, but standing in a group of free-market ideologues, I look like Trotsky.

And that raises an interesting point about where one places the “center” in these discussions and empirical measurements.
There is an initial condition problem there. There are a great many views that are simply off the line, and get excluded from the whole debate in a number of ways (for a list, one might read Chomsky or look at how people respond to him).

Posting these sort of views on hostile forums can cause the poster to get labeled, dismissed, and may actually push the debate farther in the opposite direction, by giving people evidence of an “enemy”. It is a terrible problem for people who happen to think that truth lies off the bounded left–center–right line.

I think this is the same problem that innovators in science have faced. The information aggregator model might well have rejected Galileo jst as quickly as the ecclesiastical model initially did. Anomalous data points don’t do well in large averages. However, much development can be traced back to such a data point. Think of Jules Verne or Arthur C. Clarke… at the time it was just Fiction.

Over the last five years of internet banter I’ve occassionally tried to be what you might call a “control rod” in the “nucleur reactor” of certain highly ideological forums, as in by (1) taking the non-prevailing positions using somewhat sympathetic arguments and (2) agreeing as much as I can. My experience is that this can improve online discussions by eliciting selective attempts at persuasion, but does nothing reduce the overall extremism of the forum.

As experiments go, one would like to know more about the following:

Is having a vast majority of somewhat outraged deliberators more polarizing than having a small group of real wackos? What factors most often increase conciliatory deliberating, a small number of people at each pole or some sufficient number in the middle?

Sooner or later, a group that runs away into extremism in either direction must report back to a larger society. Jury verdicts are subject to approval by a judge, or can be appealed. Judges face publication of many of their opinions and all of their results. Blogs that go far out are ridiculed or ignored. Wikis face revision.

So really the harm of group polarization is limited to the local harms that exceed the capacity of the larger society’s checks on extremism. For instance, if there are too many outrageous jury results for lawyers to appeal. One thing will help improve the checks on all of these examples, and that is open, participatory deliberation. Published judicial opinions, jury verdits, (and even settlements) are easier to critique, comment-enabled blogs are easier to refute when they err. Wikis are perhaps the ultimate in this regard.

I am personally much more in line with Habermas than Hayek. I think that information/prediction cascades happen in environments when little is known about the process. Extremism is quite easy to spot when one is well informed about the subject. For instance, lawyers familiar with the law can tell when a judge panel is being radical. However, few know how Bush’s brain works, so a nomination process that boils down to his whims is difficult to predict. It is impossible to add expert knowledge to a rumor one hears about the result, leading people to just repeat it.