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.
Veil of ignorance
The "veil of ignorance" is a method of determining the morality of issues. It amounts to imagine what a decision-maker would choose if he had enough information to know the consequences of his or her possible decisions for everyone but would not know, or would not take into account, which person he or she is. The idea is standard in moral philosophy at least since the eighteenth century. The veil of ignorance is part of a long tradition of thinking in terms of a social contract that includes the writings of Immanuel Kant, Thomas Hobbes, John Locke, Jean Jacques Rousseau, and Thomas Jefferson. Prominent modern names attached to it are John Harsanyi and John Rawls.