Groupthink, Peer Disagreement, and Rational Belief Revision

Irving Janis coined the term "groupthink" in Victims of Groupthink (1972), a psychological study of American foreign-policy fiascoes, most notably the 1961 Bay of Pigs invasion, in which he argued that cohesive decision-making groups can develop a collective drive toward consensus that overrides individual members' realistic appraisal of alternative courses of action. Janis identified several symptoms of groupthink, including an illusion of invulnerability, collective rationalization of warning signs, self-appointed "mindguards" who shield the group from dissenting information, and direct pressure on any member who expresses doubt to conform to the apparent group consensus — a social dynamic that epistemologists have since analyzed as a case where increased social cohesion and interpersonal trust, ordinarily epistemically beneficial, perversely undermines the group's collective truth-tracking capacity by suppressing exactly the kind of independent judgment the Condorcet Jury Theorem requires for its optimistic conclusion to hold.