Kahan conducted some ingenious experiments about the impact of political passion on people’s ability to think clearly. His conclusion, in Mooney’s words: partisanship “can even undermine our very basic reasoning skills…. [People] who are otherwise very good at math may totally flunk a problem that they would otherwise probably be able to solve, simply because giving the right answer goes against their political beliefs.”

In other words, say goodnight to the dream that education, journalism, scientific evidence, media literacy or reason can provide the tools and information that people need in order to make good decisions. It turns out that in the public realm, a lack of information isn’t the real problem. The hurdle is how our minds work, no matter how smart we think we are. We want to believe we’re rational, but reason turns out to be the ex post facto way we rationalize what our emotions already want to believe.

In Kahan’s experiment, some people were asked to interpret a table of numbers about whether a skin cream reduced rashes, and some people were asked to interpret a different table – containing the same numbers – about whether a law banning private citizens from carrying concealed handguns reduced crime. Kahan found that when the numbers in the table conflicted with people’s positions on gun control, they couldn’t do the math right, though they could when the subject was skin cream. The bleakest finding was that the more advanced that people’s math skills were, the more likely it was that their political views, whether liberal or conservative, made them less able to solve the math problem.