What is bias?

The brain makes thousands of decisions every day. It has neither the time nor the energy to analyze everything from scratch, so it uses shortcuts — what psychologist Daniel Kahneman calls 'System 1': fast, automatic, intuitive thinking.

These shortcuts work well most of the time. But they also produce predictable errors. When asked something hard, we often answer an easier question instead — without noticing. We remember dramatic events better than ordinary ones, and so overestimate how likely they are. We seek information that confirms what we already believe.

Bias is not a sign of stupidity or bad will. It is a side effect of a brain built for efficiency rather than accuracy.