Majority decisions tend to be made without engaging the systematic thought and critical thinking skills of the individuals in the group. Given the force of the group's normative power to shape the opinions of the followers who conform without thinking things through, they are often taken at face value. The persistent minority forces the others to process the relevant information more mindfully. Research shows that the deciscions of a group as a whole are more thoughtful and creative when there is minority dissent than when it is absent.
Philip G. Zimbardo, The Lucifer Effect: Understanding How Good People Turn Evil
conformity, decision-making, dissent, obedience, power, social-dynamics