Consider the opposite

Actively argue the case against your first conclusion before accepting it.

Why it works

Confirmation bias makes System 1 retrieve only evidence that fits the conclusion it already reached. Deliberately asking "what would make this wrong?" forces retrieval of disconfirming evidence, counteracting the one-sided search that produces overconfidence.

How to do it

1. State your conclusion, then ask: "Suppose this is wrong — why?"
2. List concrete reasons and evidence that point the other way.
3. Only then re-weigh; the goal is calibration, not flipping for its own sake.

Evidence

"Consider the opposite" is one of the better-supported debiasing techniques, shown in experiments to reduce overconfidence and hindsight and confirmation effects. (rct)

It reduces but does not eliminate bias, and it costs effort — people drop it under time pressure.

Sources

• Lord, Lepper & Preston (1984), considering the opposite reduces biased assimilation, J. Personality & Social Psychology

Common mistake

Generating a token counter-argument you never believed, then dismissing it. The exercise only works if you genuinely try to build the opposing case.