Invite an adversarial collaborator

Find someone whose genuine prior is the opposite of yours, and work together on the same evidence.

Why it works

Adversarial collaboration — proposed by Daniel Kahneman as a method for scientific disputes — assigns a person with an opposing prior to co-investigate the same question. Unlike mere exposure to opposing arguments, this requires genuine collaborative analysis, which makes dismissal structurally harder: the adversary is in the room and will challenge any motivated reasoning immediately. The shared public commitment to the outcome also reduces motivated reasoning on both sides.

How to do it

1. Identify an important decision or belief where you have a strong prior.
2. Find someone who has a genuine opposing view and a stake in being right — not just a devil’s advocate.
3. Agree on what evidence would count and share the analysis process.
4. Commit publicly to accepting the conclusion, even if it contradicts your prior.

Evidence

Adversarial collaboration was used by Kahneman and colleagues to resolve scientific disputes about unconscious cognition. Its effectiveness as an individual debiasing tool is mechanistically sound but has less formal experimental testing than the laboratory bias interventions. Mellers, Hertwig & Kahneman (2001) is a documented instance of the method in practice — opposing researchers jointly designing experiments to settle whether frequency framing eliminates conjunction effects, showing how shared commitment to the design constrains motivated reasoning. (clinical)

Adversarial collaboration requires a willing, capable, and genuinely opposing partner — difficult to arrange in everyday life. Most useful for high-stakes decisions.

Sources

• Mellers, B., Hertwig, R., & Kahneman, D. (2001). Do frequency representations eliminate conjunction effects? An exercise in adversarial collaboration. Psychological Science, 12(4), 269–275.

Common mistake

Using a "devil’s advocate" who does not actually believe the opposing view — they produce weaker, less persistent challenges than a genuine believer, and both parties know it.