Confirmation Bias

If you only remember one kind of bias to watch out for, make it this.

– Tom Chatfield

What is confirmation bias?

We live our lives using a set of beliefs. Regardless of how we gain these beliefs, through philosophical inquiry or by an opinion passed on from a friend, our natural tendency is to protect these beliefs. As we move through life, we search for evidence that supports our beliefs, and we exclude evidence that doesn’t. We call this activity of confirming and protecting our beliefs confirmation bias.

Why do we care?

Confirmation bias in and of itself isn’t a terrible thing. Without it, we’d be questioning our beliefs about everything. Our minds would be in constant flux and casting about with nowhere solid to stand. Our brains would run out of energy contemplating which 30 flavors of ice cream is our favorite or wondering if we can trust the first law of thermodynamics.

But confirmation bias can also work against us. Humans tend to seek evidence that confirms our beliefs and ignores contrary information. It’s that tendency that prevents us from changing our minds. And changing our ideas and beliefs in the face of newly discovered information is sometimes prudent.

In 1850 Dr. Ignaz Semmelweis discovered that sanitizing hands after working with cadavers drastically reduced hospital patient deaths. But surgeons didn’t begin washing their hands until the 1870s because it flew in the face of accepted medical knowledge at that time. Cognitive bias caused a lot of deaths that didn’t have to happen.

How to avoid confirmation bias.

To avoid cognitive bias, first, learn how to identify when it might be present. Signs to look out for:

  • You’re in an argument and call someone close-minded.
  • While researching a topic you notice you’re only reading information that supports your beliefs.
  • You become uncomfortable when someone challenges one of your ideas, and you immediately fight back with evidence supporting your view.

There’s no magic bullet that will help you avoid cognitive bias. It’s going to take work, and this is how you do it, actively seek out evidence that is contrary to beliefs that you hold. Take your cherished opinion or belief and do your best to rip it to shreds. If it survives, it’s worth keeping, at least for a while.

To learn more about cognitive biases check out our Critical Thinking Resource page.


  • The Little Book of Stupidity: How We Lie to Ourselves and Don’t Believe Others, by Sia Mohajer

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