In the afterword of The Ethics of Voting, I wrote up a brief account of political bias and some measures one could take to overcome it (somewhat). An excerpt:

Dangerous Biases in Politics

We suffer from many biases. Here are a few of the most dangerous in politics…

…Confirmation Bias

Confirmation bias means we tend to search for and uncritically accept evidence that favors our current opinions. We ignore, reject, are bored by, or are suspicious of evidence that undermines our current opinions. We give every benefit of the doubt to arguments and people supporting our views. We dismiss arguments and people critical of our views. We care not about the truth but about defending our turf.

Confirmation bias explains how we consume news and information. The Internet makes good information cheap and easy to get. Why isn’t everyone well informed? The problem: Most people only read news that supports their preexisting opinions. Left-liberals read the New York Times. Conservatives flock to Fox News. People who consume news want to be informed—they want to be informed that they were right all along.

In-Group/Out-Group Bias

For all but 600 of the past 200,000 generations, our ancestors’ survival depended on group solidarity in tight-knit family clans. These clans were often at war. We thus evolved with a bent toward tribalism.

We are biased to believe that our group is usually good and right, and that other groups are usually bad and wrong. We tend to stereotype and demonize members of other groups.

The psychologist Henri Tajfel produced many famous experiments testing this bias. He would randomly assign subjects to groups. He would then lie and tell group members they shared some trait. Subjects would immediately play favorites with their own group and show animosity toward other groups. For example, if asked to rate other subjects’ personalities, subjects rated people in their own group as most likable, although they had no basis for this opinion. (In the experiments, group members did not speak or interact with one another.)

Once you commit to a group identity, you become biased to forgive your group’s biggest mistakes, but to damn the other group for slight errors. You are biased to believe that anything the other side says is wrong, just because it is their view. You are biased to believe that anything your group believes or does—no matter how baseless or bad—is good, just because your group believes or does it.

The afterword was meant to be a popular treatment, but for a more scholarly account, see the excellent Oxford Handbook of Political Psychology.

Here’s a related bit from the main body of The Ethics of Voting:

…the existence of rational irrationality is supported by at least one recent psychological study. Drew Westen published an experiment on motivated reasoning, the theory that the brain tries to converge on beliefs that produce maximum positive feelings and minimize negative feelings.

Westen’s subjects were loyal Republicans and Democrats. Subjects were shown a statement by a celebrity, followed by information potentially making the celebrity seem hypocritical. Then, subjects were presented with an “exculpatory statement.” (A test run had a quote by Walter Cronkite saying he would never do TV work again after retiring, followed by footage showing he did work again after retiring, followed by an explanation saying it was a special favor.) In the experiment, the celebrities were identifiable as Republicans or Democrats. Democrat subjects strongly agreed that the famous Republicans contradicted themselves but only weakly agreed that the Democrats contradicted themselves. Republican subjects likewise readily accepted exculpatory statements from their favored party, but not the other party. Functional magnetic resonance imaging (fMRI) showed that subject’s pleasure centers were activated when condemning members of the other party, and activated again when subjects denied evidence against members of their own party.

Anyways, these kinds of biases are why I think it’s important not to be a team player. For an intellectual to see himself as belonging to Team Libertarian (or Team Left-Liberal, Team Marxist, Team Paleoconservative Academy-Hater, or whatever) is both corrupting and a sign of  existing corruption. If you find yourself defending just any work that has conclusions you agree with, you’re probably intellectually corrupt. It’s important that you be able to identify people with whom you disagree, but who you think do good work, and people with whom you agree, but who you think do bad work.

I don’t care to be on Team Libertarian. I care to be on Team Good Argument. And so I am willing to criticize libertarians who do bad work, especially when the biographical evidence available to me indicates they did bad work because they were intellectually and morally corrupt. (Mere incompetence doesn’t call for condemnation, especially public condemnation.) And I am willing to praise non-libertarians and even anti-libertarians who do good work, even if I think their arguments are ultimately flawed and their conclusions are mistaken.