I’m not a big fan of Cass Sunstein but this is pretty good (emphasis added):

There is no standard definition of the all-important term “wing nut,” so let’s provide one.  A wing nut is someone who has a dogmatic commitment to an extreme political view (“wing”) that is false and at least a bit crazy (“nut”).

When wing nuts encounter people with whom they disagree, they immediately impugn their opponents’ motivations. Whatever their religion, they are devout Manicheans, dividing their fellow citizens into the forces of light and the forces of darkness…

The good news is that wing nuts usually don’t matter. The bad news is that they influence people who do. Sadly, more information often fails to correct people’s misunderstandings. In fact, it can backfire and entrench them. Can anything be done?

For a positive answer, consider an intriguing study by Philip Fernbach, a University of Colorado business school professor, and his colleagues. Their central finding is that if you ask people to explain exactly why they think as they do, they discover how much they don’t know — and they become more humble and therefore more moderate…