Johnson and Johnson in Joining Together: Group Theory and Group Skills define effective group decisions as having these characteristics:
These authors cite studies that illustrate the power of group decision making. The first advantage is that of "process gain," in which interacting with others causes most people to think new thoughts that they wouldn't have had by considering the issue individually. The second advantage is that thinking errors or blind spots can be more easily recognized and addressed by groups. A third advantage is that groups have more accurate recall of events or factual information than individuals. A fourth advantage is that groups encourage achievement by members helping one another and giving encouragement. Humans just try harder when others give social support and cooperation! Competitiveness, fear of punishment, and embarrassment are lessened by group membership. Called "social facilitation," this process strengthens group decision making.
A fifth advantage is that involving others in decision making increases commitment in implementing the decisions that are made. Through discussion, people learn new information which may cause them to modify their opinions. They also hear persuasive arguments that may cause them to reconsider the issues. Especially if brainstorming has occurred, unique ideas may be brought to light. Additionally, people discern in discussion thoughts and impressions that are common to all in the group, so that underlying issues and ideas become apparent. Plus, in discussion, people's training and experiences add to the resources available to the group.
So what's not to like about group decision making! Well conducted, group discussions and subsequent decisions can change attitudes and behavior in people. Process determines outcome. Being able to conduct decision-making meetings is a powerful tool in meeting management!