CODEXCard 7 of 8 · Core Cognitive Biases
Confirmation bias
You seek what you already believe.
Confirmation bias is the habit of testing a belief by hunting for evidence in its favour. Once you hold a view, your attention drifts toward facts that fit and away from facts that do not. Ambiguous information gets read in the friendliest possible way. The result is a belief that feels better supported than it is.
Kahneman explains part of this through the fast mind's preference for coherence. It builds the most consistent story it can from the information in front of it and does not ask what is missing. Searching for confirming evidence is easy and pleasant. Searching for disconfirming evidence takes effort, so the slow mind rarely bothers unless pushed.
The trap many people fall into is seeing the bias clearly in others while calling their own version good judgment. That double standard is the bias itself. A fair approach applies the same scrutiny to your own conclusions as to anyone else's, and assumes you are as susceptible as the people you disagree with.
A practical counter is to write your belief down, then argue the other side as strongly as you can. If you cannot build a decent case against your own view, you probably have not looked hard enough. This pairs well with inversion, which asks you to imagine how you could be wrong.
Example
You are convinced a new coworker is lazy, and you start noticing every late arrival and long lunch. The mornings they come in early and the evenings they stay to finish a report barely register. A week of noting every arrival and departure might paint a very different picture.
Try it this week
Choose one belief you hold firmly and spend fifteen minutes this week writing the strongest case against it.
From Core Cognitive Biases (Daniel Kahneman · 2011).
