Pluralistic ignorance
In social psychology, pluralistic ignorance is a situation in which a majority of group members privately reject a norm, but go along with it because they incorrectly assume that most others accept it. This is also described as "no one believes, but everyone thinks that everyone believes". In short, pluralistic ignorance is a bias about a social group, held by the members of that social group.
Veil of ignorance
The version proposed in 1971 by American philosopher John Rawls in his "original position" political philosophy is based upon the following thought experiment: people making political decisions imagine that they know nothing about the particular talents, abilities, tastes, social class, and positions they will have within a social order. When such parties are selecting the principles for distribution of rights, positions, and resources in the society in which they will live, this "veil of ignorance" prevents them from knowing who will receive a given distribution of rights, positions, and resources in that society. For example, for a proposed society in which 50% of the population is kept in slavery, it follows that on entering the new society there is a 50% likelihood that the participant would be a slave. The idea is that parties subject to the veil of ignorance will make choices based upon moral considerations, since they will not be able to make choices based on their own self- or class-interest.