Our ability to reason did not develop simply to help us find the truth. Instead, reasoning evolved to fulfill fundamentally social functions, like cooperating in large groups and communicating with others.
This is one of the arguments advanced in “The Enigma of Reason,” a book by cognitive scientists Hugo Mercier and Dan Sperber. According to their theory of reasoning, reason’s primary strengths are justifying beliefs we already believe in and making arguments to convince others. While this kind of reasoning helps us cooperate in a social environment, it does not make us particularly good at truth-seeking. It also makes us fall prey to a number of cognitive biases, like confirmation bias, or the tendency to search for information that confirms what we believe.
Their ideas also help explain why politics seems to make us so bad at reasoning. If most of reasoning is for social cohesion instead of truth-seeking, then belonging to a particular political party should distort our reasoning and make us pretty bad at finding the truth.
A number of studies document the many ways in which our political party distorts our reasoning. One study found that people who had strong math skills were only good at solving a math problem if the solution to the problem conformed to their political beliefs. Liberals were only good at solving a math problem, for instance, if the answer to that problem showed that gun control reduced crime. Conservatives were only good at solving this problem if the solution showed that gun control increased crime. Another study found that the higher an individual’s IQ, the better they are at coming up with reasons to support a position—but only a position that they agree with.
Amazing article