Doublethink
Doublethink is a process of indoctrination in which subjects are expected to simultaneously accept two conflicting beliefs as truth, often at odds with their own memory or sense of reality. Doublethink is related to, but differs from, hypocrisy.
George Orwell coined the term doublethink (as part of the fictional language of Newspeak) in his 1949 dystopian novel Nineteen Eighty-Four. In the novel, its origins within the citizenry is unclear; while it could be partly a product of Big Brother's formal brainwashing programs, the novel explicitly shows people learning doublethink and Newspeak due to peer pressure and a desire to "fit in," or gain status within the Party—to be seen as a loyal Party Member. In the novel, for someone to even recognize—let alone mention—any contradiction within the context of the Party line is akin to blasphemy, and could subject that person to disciplinary action and the instant social disapproval of fellow Party Members.