Groupthink

In principle, a cohesive group—one whose members generally agree with one another and support one another's judgments—can do a much better job at decision making than it could if it were noncohesive. When cohesiveness is low or lacking entirely, compliance out of fear of recrimination is likely to be strongest. To overcome censor what they say out of fear of being punished socially for antagonizing their fellow members.

But group cohesiveness can have pitfalls as well: while the members of a highly cohesive group can feel much freer to deviate from the majority, their desire for genuine concurrence on every important issue often inclines them not to use this freedom. In a highly cohesive group of decision makers, the danger as "a deterioration of mental efficiency, reality testing, and moral judgment that results from in-group pressures."

Based on analyses of major fiascoes of international diplomacy and military decision making, researchers have identified groupthink behavior as a recurring pattern that involves several factors: overestimation of the group's power and morality, manifested, for example, in an illusion of invulnerability, which creates excessive optimism; closed-mindedness to warnings of problems and to factors that determine whether group cohesiveness will deteriorate into groupthink or allow for effective decision making.