What is confirmation bias, and why is it the central cognitive bias for critical thinking?

The tendency to seek, notice, and remember information that confirms what you already believe, while discounting what contradicts it.

A cognitive bias is a systematic, predictable error in how we process information — a mental shortcut (heuristic) that usually helps but reliably misfires in certain situations. Confirmation bias (Bestätigungsfehler) is the tendency to:

• search preferentially for evidence that supports your existing view,
• interpret ambiguous evidence as supporting it, and
• recall supporting cases more easily than disconfirming ones.

It's central because it directly attacks the core critical-thinking move: one of the "10 commandments" is seek refutation, not confirmation. Confirmation bias is the default that this rule has to override. It also powers filter bubbles and makes us feel certain on the basis of one-sided evidence.

Tip: The discipline that beats confirmation bias is actively trying to prove yourself wrong. If you only ever find support, you probably only ever looked for support.