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.
Invincible ignorance fallacy
The invincible ignorance fallacy is a deductive fallacy of circularity where the person in question simply refuses to believe the argument, ignoring any evidence given. It is not so much a fallacious tactic in argument as it is a refusal to argue in the proper sense of the word, the method instead being to either make assertions with no consideration of objections or to simply dismiss objections by calling them excuses, conjecture, etc. or saying that they are proof of nothing; all without actually demonstrating how the objection fit these terms (see ad lapidem fallacy).