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.
Argument from ignorance
Argument from ignorance (from ), also known as appeal to ignorance (in which "ignorance" represents "a lack of contrary evidence") is a fallacy in informal logic. It asserts that a proposition is true because it has not yet been proven false or a proposition is false because it has not yet been proven true. This represents a type of false dichotomy in that it excludes the possibility that there may have been an insufficient investigation to prove that the proposition is either true or false. It also does not allow for the possibility that the answer is unknowable, only knowable in the future, or neither completely true nor completely false. In debates, appeals to ignorance are sometimes used in an attempt to shift the burden of proof. In research, low-power experiments are subject to false negatives (there would have been an observable effect if there had been a larger sample size or better experimental design) and false positives (there was an observable effect, however this was a coincidence due purely to random chance, or the events correlate, but there is no cause-effect relationship). The term was likely coined by philosopher John Locke in the late 17th century.