Extraordinary Popular Delusions and the Madness of Crowds documents national delusions, peculiar follies and philosophical delusions. Collective delusions have always existed and they still do and they may cause serious harm. So how is it possible they exist at all? And how may we break their power over us?
Steven Pinker explains part of how it is possible that delusions on a large scale exist: "If dissenters are punished and can anticipate they are going to be punished then you might have a situation that no one actually believes something but everyone believes that everyone else believes it. And therefore no one is willing to be the little boy who says the emperor is naked. And this pluralistic ignorance as it is sometimes called is easily implemented when you have the punishing or censoring of unpopular [dissenting, CV] views."
Whether they are tied to religion, nationalism or other ideologies, collective delusions exist and may thrive when the expression and critical evaluation of ideas is suppressed. In those circumstances they may not only hurt us but also control us to such an extent that when we start to realize that they are delusions we may feel unable to expose them. This is why the suppression of the freedom to express dissenting ideas and critically evaluate dominant beliefs is dangerous to all of us.
This is why freedom of expression of dissenting ideas, including ideas which may be perceived as offensive, remains so important. It is an essential ingredient for societal progress.