Pluralistic ignorance
Pluralistic ignorance can be contrasted with the false consensus effect. In pluralistic ignorance, people privately disdain but publicly support a norm (or a belief), while the false consensus effect causes people to wrongly assume that most people think like they do, while in reality most people do not think like they do (and express the disagreement openly). For instance, pluralistic ignorance may lead a student to drink alcohol excessively because she believes that everyone else does that, while in reality everyone else also wishes they could avoid binge drinking, but no one expresses that due to the fear of being ostracized. A false consensus for the same situation would mean that the student believes that most other people do not enjoy excessive drinking, while in fact most other people do enjoy that and openly express their opinion about it.
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.