Have you considered a CAPTCHA-like system whereby you must solve some propositonal logic puzzle or calculate conditional probabilities before being allowed to comment?
It seems to me that something like this may help promote constructive discussion by (1) filtering out those of low analytical ability, (2) bumping those with sufficient analytical ability up into system 2 thinking, and (3) priming everyone with a problem in which they are actually seeking an answer rather than merely justifying a previously held belief.
I think that that would be a very interesting experiment. You'd have to choose a problem that people couldn't simply Google, but we aren't aiming for a perfect filter, just a good enough filter.
In a recent poll, many LW members expressed interest in a separate website for rational discussion of political topics. The website has been created, but we need a group of volunteers to help us test it and calibrate its recommendation system (see below).
If you would like to help (by participating in one or two discussions and giving us your feedback) please sign up here.
About individual recommendation system
All internet forums face a choice between freedom of speech and quality of debate. In absence of censorship, constructive discussions can be easily disrupted by the inflow of the mind-killed which causes the more intelligent participants to leave or descend to the same level.
Preserving quality thus usually requires at least one of the following methods:
On the new website, we are going to experiment with a different method. In brief, the idea is to use an automated recommendation system which sorts content, raising the best comments to the top and (optionally) hiding the worst. The sorting is done based on the individual preferences, allowing each user to avoid what he or she (rather than moderators or anyone else) defines as low quality content. In this way we should be able to enhance quality without imposing limits on free speech.
UPDATE. The discussions are scheduled to start on May 1.