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").
A wing nut might believe George W. Bush is a fascist, Barack Obama is a socialist, big banks run the Department of the Treasury or that the U.S. intervened in Libya because of oil.
When wing nuts encounter people with whom they disagree, they impugn their opponents' motivations. They divide their fellow citizens into the forces of light and the forces of darkness.
Wing nuts have a lot of fellow travelers - people who don't fit the definition, yet whose views, though not crazy, aren't exactly evidence-based. You can be a wing nut on a particular issue without being one in general. Most of us can hear the voice, at least on occasion, of our inner wing nut.
The good news is wing nuts usually don't matter. The bad news is 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?
Consider an intriguing study by Philip Fernbach, a University of Colorado professor, and his colleagues. They found 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.
The study came in four stages. First, people were asked to state their positions on a series of political issues, including a cap-and-trade system for carbon emissions, a national flat tax, merit-based pay for teachers and unilateral sanctions on Iran for its nuclear program. They were asked to describe their position on a seven-point scale whose endpoints were "strongly in favor" and "strongly opposed."
Second, people were asked to rate their degree of understanding of each issue. The third step was the crucial one; they were asked to "describe all the details you know about (for example, the impact of instituting a 'cap and trade' system for carbon emissions), going from the first step to the last, and providing the causal connection between the steps." Fourth, people were asked to rerate their understanding and to restate their position on the relevant issue.
The results were stunning. On every issue, the result of requesting an explanation was to persuade people to give a lower rating of their own understanding - and to offer a more moderate view on each issue. In a follow-up experiment, Fernbach and his co-authors found that after being asked to explain their views, people were less likely to want to give a bonus payment to a relevant advocacy group.
Interestingly, Fernbach and his co-authors found no increase in moderation when they asked people not to "describe all the details you know" about the likely effects of the various proposals, but simply to say why they believe what they do. If you ask people to give reasons for their beliefs, they tend to act as their own lawyers or public relations managers, and they don't move toward greater moderation. The lesson is subtle: What produces an increase in humility, and hence moderation, is a request for an explanation of the causal mechanisms that underlie people's beliefs.
The economist Albert Hirschman lamented the "overproduction of opinionated opinion." He feared strong opinions, as such, "might be dangerous to the health of our democracy," because they can make it harder for people to understand one another and to find mutually agreeable solutions.
If Fernbach and his co-authors are to be believed, the problem is curable - at least if those who have "opinionated opinions" have less than solid foundations for their beliefs and if they can be convinced of that fact.
For wing nuts and their many fellow travelers, however, there is a serious obstacle, and it goes by the name of "motivated reasoning." When people have a strong emotional attachment to their initial convictions, they tend to heap ridicule on anything that runs counter to those convictions and to give a lot of weight to anything that supports them.
Motivated reasoning helps to account for two defining characteristics of wing nuts and their fellow travelers: a readiness to attack people's good faith, rather than their actual arguments, and an eagerness to make the worst, rather than the best, of opposing positions.
If Fernbach and his co-authors are right, this obstacle may not be insuperable. Efforts to examine the assumptions behind your own beliefs, and to identify what you don't know, are likely to produce an increase in humility. Whether or not you change your view, you may be humbled - and end up being more charitable to those who see things differently.
Cass R. Sunstein, a professor at Harvard Law School, is a Bloomberg View columnist. He is the former administrator of the White House Office of Information and Regulatory Affairs and author of "Simpler: The Future of Government."