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.
Willful blindness
Although the term was originally—and still is—used in legal contexts, the phrase "willful ignorance" has come to mean any situation in which people intentionally turn their attention away from an ethical problem that is believed to be important by those using the phrase (for instance, because the problem is too disturbing for people to want it dominating their thoughts, or from the knowledge that solving the problem would require extensive effort).