I've often wondered what would be possible in terms of designing a website that aims to moderate debate in a way that leads to new ideas and conclusions and attempts to negate as many of these types of effects as possible.
Some formal system, that the users would have no choice but to follow, that begins with some one making a statement such as "X is true because of Y and Z" and then everyone debates it, reforms the statement as necessary and at some point it gets locked in as either true or false and then the discussion has to proceed based on that understanding.
People are forced to address each others points and eliminate as much bias as possible in their statements.
You could visually map out the progress that gets made until perhaps some new interesting conclusion gets reached.
Obviously no perfect solution exists but for me its an interesting question of how useful a system could be designed. There's also the obvious problems that a) few people are likely to want to use such a system and b) those that do are probably skewed to favor some particular point of view.
There is just so much wasted energy on the internet not being harnessed for actual progress. There are many blogs etc that have been created with the specific purpose of progressing some cause or area of expertise but people are just turning up, yelling opinions at one another and leaving with very little gained. Such is life I guess...