As observed by Aldag and Fuller (1993), the groupthink phenomenon seems to rest on a set of unstated and generally restrictive assumptions:

• The purpose of group problem solving is mainly to improve decision quality
• Group problem solving is considered a rational process.
• Benefits of group problem solving:
  • variety of perspectives
  • more information about possible alternatives
  • better decision reliability
  • dampening of biases
  • social presence effects
• Groupthink prevents these benefits due to structural faults and provocative situational context.
• Groupthink prevention methods will produce better decisions
• An illusion of well-being is presumed to be inherently dysfunctional.
• Group pressures towards consensus lead to concurrence-seeking tendencies.

According to Janis, decision-making groups are not necessarily destined to groupthink. He devised ways of preventing groupthink:

• Leaders should assign each member the role of "critical evaluator." This allows each member to freely air objections and doubts.
• Leaders should not express an opinion when assigning a task to a group.
• Leaders should absent themselves from many group meetings to avoid excessively influencing the outcome.
• The organization should set up several independent groups working on the same problem.
• All effective alternatives should be examined.
• Each member should discuss the group's ideas with trusted people outside of the group.
• The group should invite outside experts into meetings. Group members should be allowed to discuss with and question the outside experts.
• At least one group member should be assigned the role of devil's advocate. This should be a different person for each meeting.