Pluralistic ignorance
Everyone privately doubts a norm, but each assumes everyone else accepts it, so it survives.
What it means
Pluralistic ignorance is a state in which most members of a group privately reject a norm or belief yet go along with it because they mistakenly believe that most others accept it. The mechanism is a collective misreading of public behavior: because everyone conforms outwardly, each person infers private endorsement from others' compliance, while keeping their own dissent hidden — so the silence is self-reinforcing. It differs from simple conformity in that the conformity is grounded in a false belief about what the group actually thinks, which means the norm has no real majority support at all. The condition is fragile: making private attitudes visible, or simply correcting the misperception of what others believe, can cause the apparent consensus to collapse quickly. It has been documented in campus drinking, classroom participation, bystander inaction, and support for unpopular regimes, where fear of being the lone dissenter sustains a norm few privately hold. It matters because it traps groups in arrangements almost no one wants, and because the remedy — surfacing true preferences — is often cheap.
Examples
Students overestimate their peers' comfort with heavy drinking, so each drinks more to fit a norm that few of them actually endorse.
After a baffling all-hands, nobody asks a question — each person reads the silence as everyone else following along, and stays quiet rather than look like the only one lost.
Neighbors keep up an exhausting Christmas light display every year, each convinced the others love it; the first household to skip it finds relief, not scandal.
First described in Floyd Allport; Katz & Allport (1931).