Have you ever noticed the group dynamic in which a patently foolish idea or ideas gains momentum in a discussion, with everyone sort of going along -- until one person courageously speaks up and raises a solid objection? That can change the whole direction of a conversation. Groupthink is unfortunately how much evil is perpetuated in the world, when the ignorant or malicious exploit it. Fortunately, one person standing up in speech can arrest groupthink’s momentum, inducing other objectors to speak up and forcing the group as a whole to deliberatively rethink their claims. This often leads to the rejection, modification, or slowing of bad ideas and bad policy, and at a minimum gets people to examine assumptions they take for granted. It’s partly what is meant by the maxim, “Let cooler heads prevail.”
Why does groupthink happen at all? One explanation is a cognitive bias called the “bandwagon effect,” in which people do or believe things simply because others do; humans are social animals that tend to follow the lead of others, especially in unfamiliar situations where someone else seems to know what they are doing. Another cognitive bias is “false consensus,” a tendency for people to believe that others agree with them more than they actually do. And certainly there are groupthink pressures from society and culture, or subcultures: in some group situations non-consensus opinions are more welcomed (many or most graduate seminars in philosophy) while in others conformity is expected or even imposed (many corporate boardrooms, or in ideological think tanks).
The problem is that once the momentum of a discussion gets going in a bad direction, people around the table may silently nod their heads in agreement, perhaps thinking that the initial discussant has some special authority or expertise, or going along because they believe that the group as a whole concurs with the original claim. Thus people often don't say anything in the face of objectionable ideas or policy, which only allows those bad ideas or policies to flourish uncontested. It is that contestation of ideas that gives deliberation its power, whether in a small meeting or in a large modern democracy. And contestation doesn’t occur unless someone speaks up first.
Speaking up works because it breaks the hold of groupthink. It snaps people’s brains to attention and induces them to think with more conscious effort about the topic at hand. It makes others who may object, but are doing so silently, see that they are not alone in their doubts, and that those doubts are not unreasonable but are, in fact, worthy of talking about. Speaking up also works by exposing the merits of other perspectives to the group, which probably has only been exposed to limited perspectives so far. And when the conversation has been dominated by one perspective or one person, speaking up arrests the momentum, putting those who have dominated the floor on notice that their claims will be subject to critical examination.
(I want to note that it does not follow from any of this that all consensus is bad. Indeed, people wouldn't be able to function socially and cooperatively without forming consensus views on a great many things. But any consensus -- even a well-supported theory from the sciences -- is subject to revision in light of better evidence, or of historical context, or of the more complete picture offered by different or wider perspectives. Not all consensuses are false products of groupthink, but all consensuses are, in principle, subject to critical examination. As John Stuart Mill rightly wrote, if deliberation doesn’t reveal flaws, then it gives us more confidence in the original opinion and allows us to support the consensus with greater confidence.)
Speaking up takes courage. It is not always an easy thing to do, but it does get easier with practice. It is important, to encourage yourself, to know that you might head off something bad just by talking and changing the direction of a conversation. I know that I have prevented some bad things from happening in the organizations I’ve belonged to -- in the military, in government, in academia, in charitable organizations -- simply by stopping the momentum of a bad idea and getting people to think more critically. Speaking up is also not an either-or proposition, for sometimes you will have a partial success, slowing or diverting a bad policy even if you don’t stop it. Partial success is better than no success. Furthermore, by speaking up you can open an initial crack in people’s habits of thought which can widen with time, for it usually takes time for people to accept new or different ideas. Like dripping water that wears away a rock face, patient, persistent effort is often necessary to make headway, but speaking up in the first instance is one place to start.