Why it was said

Rolf Dobelli gives confirmation bias two chapters of the ninety-nine in The Art of Thinking Clearly and opens the first with this line. He treats it as the root from which most of the other errors grow.

What it actually means

Once you hold a view, evidence for it looks like proof and evidence against it looks like noise, and this does not feel like bias from the inside; it feels like being right. Dobelli calls it the mother of misconceptions because it protects every other error from correction: the sunk cost, the story, the forecast all survive because the mind collects what agrees with them. The defence is to look for the disconfirming case on purpose, since it will never arrive on its own.

How to use it

1. 1For your current strongest opinion, write the evidence that would change it, then go and look for that evidence.
2. 2Assign someone, or yourself for ten minutes, to argue the other side properly before a decision.