The false consensus effect is the tendency for people to project their way of thinking onto other people.[1] In other words, they assume that everyone else thinks the same way they do. This supposed correlation is unsubstantiated by statistical data, leading to the perception of a consensus that does not exist. This logicalfallacy involves a group or individual assuming that their own opinions, beliefs and predilections are more prevalent amongst the general public than they really are.
This bias is commonly present in a group setting where one thinks the collective opinion of their own group matches that of the larger population. Since the members of a group reach a consensus and rarely encounter those who dispute it, they tend to believe that everybody thinks the same way.
As an extension, when confronted with evidence that a consensus does not exist, people often assume that the others who do not agree with them are defective in some way.[2] There is no single cause for this cognitive bias; the availability heuristic and self-serving bias have been suggested as at least partial underlying factors. There could also be protective mechanisms behind this phenomenon.
Ross L., Greene D. & House, P. (1977). The false consensus effect: An egocentric bias in social perception and attribution processes. Journal of Experimental Social Psychology13, 279-301.
Fields, James M., and Howard Schuman, (1976-77) "Public Beliefs about the Beliefs of the Public," Public Opinion Quarterly, 40: 427-448.
