Crimestop is a concept of Newspeak, featured in George Orwell's 1984. It denotes a learned mental discipline; a conditioned inability even to grasp thoughts contrary to one's own belief system.
"Crimestop means the faculty of stopping short, as though by instinct, at the threshold of any dangerous thought. It includes the power of not grasping analogies, of failing to perceive logical errors, of misunderstanding the simplest arguments if they are inimical to Ingsoc, and of being bored or repelled by any train of thought which is capable of leading in a heretical direction. Crimestop, in short, means protective stupidity." 
Enthetha in Scientology
Probably the closest example of the principle in practice can be seen in the doctrine of the Church of Scientology to regard certain information as Entheta. Entheta, short for 'enturbulated theta', is any thought, concept or argument that might be damaging to the Church of Scientology. Scientologists are required to actively avoid any and all entheta, regardless of whether it is true or not. It is a serious violation of Scientology ethical standards to even hear or read any entheta, the Church members must take every step to isolate themselves from it via self-censorship. Failure to do so can result in punishment and/or extra auditing hours having to be bought (at hundreds of dollars an hour).
- ↑ p. 220, 1984 - George Orwell, Penguin, 1989
- ↑ Thought Control - Ask the Scientologist
- ↑ Operation Clambake - Scientology v 1984