Chris Mooney has a great piece in Mother Jones on why people aren’t persuaded by evidence:
In Kahan’s research (PDF), individuals are classified, based on their cultural values, as either “individualists” or “communitarians,” and as either “hierarchical” or “egalitarian” in outlook. (Somewhat oversimplifying, you can think of hierarchical individualists as akin to conservative Republicans, and egalitarian communitarians as liberal Democrats.) In one study, subjects in the different groups were asked to help a close friend determine the risks associated with climate change, sequestering nuclear waste, or concealed carry laws: “The friend tells you that he or she is planning to read a book about the issue but would like to get your opinion on whether the author seems like a knowledgeable and trustworthy expert.” A subject was then presented with the résumé of a fake expert “depicted as a member of the National Academy of Sciences who had earned a Ph.D. in a pertinent field from one elite university and who was now on the faculty of another.” The subject was then shown a book excerpt by that “expert,” in which the risk of the issue at hand was portrayed as high or low, well-founded or speculative. The results were stark: When the scientist’s position stated that global warming is real and human-caused, for instance, only 23 percent of hierarchical individualists agreed the person was a “trustworthy and knowledgeable expert.” Yet 88 percent of egalitarian communitarians accepted the same scientist’s expertise. Similar divides were observed on whether nuclear waste can be safely stored underground and whether letting people carry guns deters crime. (The alliances did not always hold. In another study (PDF), hierarchs and communitarians were in favor of laws that would compel the mentally ill to accept treatment, whereas individualists and egalitarians were opposed.)
There are a lot of bad policy consequences associated with humanity’s tendency to reason like this, and I don’t really know how to solve them. But it’s worth trying to fight confirmation bias in your own life by making sure to make an effort to seek out strong arguments against your own point of view. The world is full of bad arguments, and it’s easy to become obsessed with how bad the arguments being made by “the other side” are. And at times this is an important fact about the world. But it’s worth making sure you’re up-to-date on what the strongest arguments for the other side are.