This is what Wikipedia says about Groupthink:
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. Group members try to minimize conflict and reach a consensus decision without critical evaluation of alternative viewpoints by actively suppressing dissenting viewpoints, and by isolating themselves from outside influences.
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“). Furthermore, groupthink can produce dehumanizing actions against the “outgroup”.
More at: https://en.wikipedia.org/wiki/Groupthink
The following are excerpts from “GROUP DYNAMICS AND THE ART OF LEADERSHIP”:
1. Leadership is a function of the group, not of any individual. The group is conceived as an independent, self-directing organism. A number of functions must be performed in its service if it is to operate efficiently, of which the leadership functions are one type. It is more accurate to refer to “leadership functions” than to refer to “a leader”. For the leadership functions may at times be performed by several or all of the group members, as well as by a designated “leader”.
2. Leadership is responsible for establishing the climate of the group. The climate of the group is determined largely by the person who helps organize it. His actions can produce an atmosphere of competition and hostility, formality and reserve criticism and threat, or permissiveness and freedom. If he regards himself as an authority or as possessing some kind of superiority, his actions are likely to be of a directing type, and the group climate will be authoritarian. The group members will certainly feel somewhat restricted in what they can or cannot do, at least until they get the approval of the leader.
3. Leadership helps the group to define its purposes and objectives. One method found useful in determining group objectives is to conduct a problem-census in which the members of the group state the problems they are concerned about that might be considered by the group. These can be listed, priorities can be assigned to them, and general objectives can be drawn from them. The leader is free to express his own needs as the needs of a member of the group, not as the desires of a superior.
4. Leadership helps the group to organize itself. When the group defines its objectives, it really is taking the first step in organizing itself, since a group’s objectives greatly influence its form of organization. For example, a group that exists primarily for the purpose of receiving instruction is likely to put more emphasis on the role of resource leadership than would a group that exists for the purpose of social fellowship.
More at: http://bathtubbulletin.com/group-dynamics-art-leadership-courtesy-prosperos/