“I beseech you, in the bowels of Christ, think it possible you may be mistaken.”― Oliver Cromwell

Five years ago, I wrote a book about evolution and human cognition. In my research for that book, I learned two things that are, perhaps, the most depressing things I know: 1) that human reason did not evolve to help us find the truth; and 2) that people are spectacularly bad at using reason to reach correct conclusions, but spectacularly good at using it to defend conclusions arrived at in unreasonable ways.

The reasons for this lie deep in our reptilian brains. Nature selects for brains that can recognize

useful information—and in ancestral environments, utility and truth were only acquainted casually. Winning, on the other hand, is always useful. Organisms that compete successfully within their own species end up with more resources, more mating opportunities, and more offspring. Fortune favors the belligerent.

This is why it is almost impossible to have a decent political argument these days—and, by “these days,” I mean “since the middle of the Pleistocene Era.”

The cognitive obstacles that prevent us from talking productively about different values all contribute to what psychologists call the “confirmation bias.” We are all, to put it bluntly, profoundly, irrevocably, and quite possibly fatally biased toward whatever we happen to believe. And this bias controls the way that we process anything that might count as evidence in a political or a religious discussion.

If your Facebook feeds look anything like mine, then, at least once a day, you see a link to an article or an editorial expressing an over-the-top partisan position attached to words like” “finally, somebody is telling the truth” or “if every American would read this article, we would be rid of _____ for good.”

A message like this asserts roughly the following narrative: “Everything that anybody on the other side has ever said is factually incorrect, morally deficient, and intellectually embarrassing, and the article I have linked to is a self-evident truth that anybody who is not stupid, crazy, or evil should be able to recognize immediately.”

And let’s be honest, most of us feel this way a lot of the time. We are designed to feel this way. We have been programmed by millions of years of evolution to see the world as a series of events and inputs that confirm whatever we happen to believe. We are many times more likely to see information that confirms what we think as “true” and to dismiss information that challenges our beliefs as “false,” “biased,” “misleading,” or “wrong.”

And there may very well be nothing that we can ever do about it. We probably do not even have the ability to reason outside of the confirmation bias. But we can recognize it. We can be aware, going in to a debate or discussion, that our mind is going to process evidence in the way most favorable to us and most damaging to our opponents. And we can try to take to heart Oliver Cromwell’s advice to the General Assembly of the Church of Scotland almost 400 years ago: “I beseech you, in the bowels of Christ, think it possible you may be mistaken.” It is, I should add, advice that Cromwell was far better at giving than at taking.

But it is good advice nonetheless. Meaningful political discussions require an environment where everyone can influence, and be influenced by, everybody else—and this sort of environment simply cannot be produced by people who cannot recognize when they are in the grip of a confirmation bias.  Until we actually accept the possibility that we are wrong, we are unlikely ever to have the kind of conversations in which we can prove that we are right.