(Janis 1972) A mode of thinking in cohesive groups in which the drive for unanimity overrides a realistic appraisal of alternative courses of action. It is the social analogue of individual bias — consensus pressure degrading the quality of analytic judgement in teams.
Symptoms
- Illusion of invulnerability — collective overconfidence and risk-taking.
- Collective rationalisation — dismissing warnings that contradict the shared view.
- Self-censorship and pressure on dissenters; "mindguards" who shield the group from disconfirming information.
- Illusion of unanimity — silence read as agreement.
In intelligence analysis
- Analytic teams converge on an estimate without genuine challenge; dissent is suppressed or self-censored.
- Reinforces Confirmation Bias at the group level — the group confirms a shared view rather than testing it.
Countermeasure
- Devil's Advocacy and red-teaming: appoint someone to argue against the prevailing judgement.
- Structured techniques (ACH) and parallel/anonymous assessment so dissent is not personally costly.
- Deliberately invite outside perspectives before the group converges.
Related
- Cognitive Bias — the taxonomy this bias sits within
- Confirmation Bias — the individual-level analogue
- Structured Analytic Techniques — Devil's Advocacy, red-teaming