Plural ignorance

Plural ignorance or pluralistic ignorance is a term which gives a name to a situation where a majority of group members privately reject a norm, but at the same time, they assume incorrectly that most others accept it. The term describes a context in which "no one believes, but everyone thinks that everyone believes." 
A context of plural ignorance can be caused by the structure of the underlying social network.
A situation of plural ignorance develops when each individual decision-maker in a group of decision-makers does not have the necessary information to solve a problem.
History.
The term "pluralistic ignorance" was coined by Daniel Katz and Floyd H. Allport in 1931. 
Plural ignorance may partially explain why people are more likely to intervene in an emergency situation when alone than when other persons are present. If people monitor the reactions of others in such a situation, they may conclude from the inaction of others that other people think that it is not necessary to act.