Groupthink is a psychological phenomenon that occurs within a group of people in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome. Cohesiveness, or the desire for cohesiveness, in a group may produce a tendency among its members to agree at all costs. This causes the group to minimize conflict and reach a consensus decision without critical evaluation.
Groupthink requires individuals to avoid raising controversial issues or alternative solutions, and there is loss of individual creativity, uniqueness and independent thinking. The dysfunctional group dynamics of the “ingroup” produces an “illusion of invulnerability” (an inflated certainty that the right decision has been made). Thus the “ingroup” significantly overrates its own abilities in decision-making and significantly underrates the abilities of its opponents (the “outgroup”).