People have a tendency to interpret new facts as being consistent with their strongly held beliefs. This propensity, known as confirmation bias, is well known. What is not generally appreciated, however, is that confirmation bias is not just a mild affliction. It is a dominating factor in human thinking — especially with matters distant from one’s direct personal experience. 

Nobel Prize-winning cognitive psychologist Daniel Kahneman explained that “confirmation bias comes from when you have an interpretation, and you adopt it, and then, top down, you force everything to fit that interpretation.” And Karl Popper noted “if we are uncritical we shall always find what we want: we shall look for, and find, confirmations, and we shall look away from, and not see, whatever might be dangerous to our pet theories.”

Confirmation bias has two basic components. First, we embrace and amplify facts that confirm our existing narratives. And second, we resist and diminish evidence that is inconsistent with our narratives.

Confirmation bias is endemic in politics. And it’s getting worse. Today’s unprecedented partisanship largely results from the toxic mixture of confirmation bias and an explosion of information. The internet is an elaborate menu allowing people to pick and choose what they want to believe.

The examples of confirmation bias in politics are endless. Conservatives, for instance, often celebrate the “Trump economy,” citing the stock market as a principal reason why President Donald Trump runs the economy significantly better than President Barack Obama. The fact that the stock market increased 150 percent under Obama (and has increased significantly less under Trump) is typically missing from the presentation.

Sure, Trump has been president less than half as long as Obama was. And grading economic performance requires looking beyond simply the stock market. But to ignore Obama’s historically impressive stock market record — while touting Trump’s performance — is confirmation bias on full display.

On the other side of the aisle, there is a constant liberal drumbeat that Trump is soft on Russia. But Trump has sanctioned Russia repeatedly, expelled Russian diplomats from the U.S. and sold arms to Russian foe Ukraine. And Trump ordered the bombing of Russian ally Syria — where Russia’s military maintains a significant presence — prompting Vladimir Putin to call the strikes an “act of aggression” that could “have a destructive effect on the entire system of international relations.”

True, Trump’s relationship with Russia is complicated and his behavior regarding Putin raises legitimate concerns, but to ignore the numerous hard lines Trump has drawn with Russia distorts and oversimplifies the story.

As Charlie Munger noted, Charles Darwin “always gave priority attention to evidence tending to disconfirm whatever cherished and hard-won theory he already had. In contrast, most people early achieve and later intensify a tendency to process new and disconfirming information so that any original conclusion remains intact.” 

Darwin’s approach of resisting confirmation bias and seeking facts that conflict with our own narratives is best. Giving a fair shake to disconfirming evidence sometimes forces us to concede our theory was wrong, which isn’t easy for us prideful humans. But doing so is, as Darwin understood, far better than continuing to embrace a false narrative. 

William Cooper has written for The Wall Street Journal, Baltimore Sun, New York Daily News, St. Louis Post-Dispatch and USA Today, among others.