->''"To know and not to know, to be conscious of complete truthfulness while telling carefully constructed lies, to hold simultaneously two opinions which cancelled out, knowing them to be contradictory and believing in both of them, to use logic against logic, to repudiate morality while laying claim to it, to believe that democracy was impossible and that the Party was the guardian of democracy, to forget whatever it was necessary to forget, then to draw it back into memory again at the moment when it was needed, and then promptly to forget it again: and above all, to apply the same process to the process itself. That was the ultimate subtlety: consciously to induce unconsciousness, and then, once again, to become unconscious of the act of hypnosis you had just performed. Even to understand the word 'doublethink' involved the use of doublethink."''

The ability to simultaneously believe in at least two or more mutually contradictory concepts, without any [[FridgeLogic cognitive dissonance]]. You do know better and what's really true, but you still keep BelievingYourOwnLies as the truth just because.

There are two kinds of straight examples here: ''Verified'' examples, where a reliable narrator or similar gives the audience insight into the mind of the character, and ''apparent'' examples where a character appears to be engaging in doublethink but we don't know for sure what's really going on in his mind. Examples of the latter kind are more effective when a character suspects another of doublethink.

{{Hypocrite}}s often engage in doublethink, though the StrawHypocrite doesn't have to, being dishonest to others rather than themselves. In cases where doublethink is combined with some version of TheMasquerade, it becomes an extremely potent tool of the ConsummateLiar: No liar is as believable as the honest liar who truly believes in his own lies.

Compare and contrast NoExceptYes and FromACertainPointOfView, where a character tries to glue opposing viewpoints together as being the same thing, giving it a resemblance of coherence by various esoteric distinctions. Compare MemoryGambit & PoesLaw. Contrast BecomingTheMask, where cognitive dissonance sets in and a character who has pretended to be loyal to a certain group starts gaining true loyalty towards it, and BothSidesHaveAPoint where both sides are respected but kept separated. See also TwoPlusTortureMakesFive and TheTreacheryOfImages.

* The entire ''Film/SuckerPunch'' story runs on this, as the character(s) live simultaneously in two or sometimes even ''three'' different levels of realities, requiring quite a bit of multitasking from the audience if they are to have any real clue as to what's going on. [[spoiler:At the end it is revealed that Baby Doll did manage to help Sweet Pea to escape in the real world. This means that she must have been active in all three realities simultaneously, and actually accomplishing real deeds while trapped within a dream within a show within a hallucination. Wow.]]

* George Orwell's ''Literature/NineteenEightyFour'' is the TropeNamer. The party requires that all citizens believe everything that the party says, even when they know for a fact that it is not true. Ingrained in this concept is also the idea that YourMindMakesItReal. If everyone believes that something is true, then it ''is'' true. Thus, the party can literally dictate reality.
* ''Literature/{{Discworld}}'':
** Dios and the other Djelibeybian priests from ''[[Literature/{{Discworld}} Pyramids]]'' are noted for this ability, as religious dogma in that country obliges them to believe that several different gods all exclusively and simultaneously fill the same divine offices. Most of the priests are dedicated to one god (not dismissing the existence of the others, but at least not having to think about their interaction too much), but as high priest Dios believes in all of them.
** Vorbis from ''Discworld/SmallGods'' has mastered doublethink to the levels applied by [[Literature/NineteenEightyFour the Party]], as he's quite comfortable declaring that the way things may actually be found to be in the world is insignificant compared to the [[TheFundamentalist fundamental]] truth. For example, if you could actually go to the edge of the world and see that it is a disc (which you can, in this case), that doesn't matter because the real truth still is and always will be the dogma that the world is round, though of course anyone claiming it's a disc must be silenced before they corrupt the minds of believers.
* In order to use [[FunctionalMagic sympathy]] in ''TheKingkillerChronicle'', one must be able to hold two opposite beliefs at once. It sounds simple at first, but it's also one of the reasons most Arcanists go mad.
* In ''Literature/BlaTornet'', the protagonist survives through his youth by developing this mindset. He is truly a heretic, but he is also a priest in a society hellbent on sniffing out all heretics and burying them alive. His solution is to never lie, a lie would eventually be discovered. Instead, he actively chose to believe in two simultaneous realities... and he quite incorrectly assumes that everyone else is smart enough to pull off the same kind of dual reality. In reality, almost everyone else in his world is actually exactly as narrow-minded as they come across.
* In CHERUB:Divine Madness, the Survivor's manipulate people into joining their cult whilst simultaneously not seeing that they are being manipulated.
* In ''Literature/CatsCradle'', the religion of Bokononism is essentially built around doing this for the sake of comforting oneself: The Book of Bokonon preaches that one should "live by the foma [shameless lies] that make you brave and kind and healthy and happy". In fact, the first sentence of the Book reads "all of the true things that I am about to tell you are shameless lies." Basically, Bokononists are aware that all the principles and mythology of Bokononism are basically stuff that Bokonon made up because he thought it sounded nice, but they continue to wholeheartedly believe and practice it because it gives them comfort and makes them better people.
-->"Anyone unable to understand how a useful religion can be founded on lies will not understand this book either. So be it."
-->-'''John''', the novel's narrator
* In "The Beguiling", Literature/CiaphasCain describes his aide Jurgen thus: "He wasn't the biggest bang in the armoury by any means, but made up for his lack of intellect with a literally minded approach to orders and an unquestioning acceptance of even the mutually contradictory parts of Imperial doctrine which would have done credit to the most devout ecclesiarch."
* In ''TheHandmaidsTale'', the protagonist doesn't know what's happened to her husband, but states that she simultaneously believes that he was killed, that he was captured, and that he escaped.
* In ''Literature/TheDaggerAndTheCoin'', the members of the Spider Priest cult possess a combined LivingLieDetector and CompellingVoice ability, and while they seem to sincerely believe they are fighting against lies and spreading truth, in practice, their powers are used in a sinister way. If someone sincerely believes something, even if false, it registers as "true" to a Spider Priest, and they can convince each other and muggles of its truth without feeling any cognitive dissonance. The Priests claim to hate books because people can lie with the written word in a way they cannot with speech, but they define the truth as whatever they say it is, and use their powers to make people doubt facts contained in texts and instead believe in the lies [[BelievingTheirOwnLies sincerely preached by the Spider Priests]].

* In one [[http://en.wikipedia.org/wiki/Chain_of_Command_%28Star_Trek:_The_Next_Generation%29 unusually creepy episode]] of ''Series/StarTrekTheNextGeneration'', [[spoiler:Picard]] gets captured as a spy and tortured by the enemy. One recurring question is how many lights are illuminating the room. It's really four, but the torturer [[TwoPlusTortureEqualsFive insists that they are five]] - and he isn't satisfied with a lie about there being five lights, the hero is required to truly believe it. In the end, [[spoiler:the protagonist thinks he truly sees five lights for a moment, and he later confesses this to the ship's counselor. While the torture scene is directly inspired by ''Literature/NineteenEightyFour'', the ending offers a few new twists to the theme. "[[ShutUpHannibal There are FOUR lights!]]"]]
* In an episode of ''Series/{{Frasier}}'', Frasier gets irrationally bothered by the thought of Daphne having sex with her new boyfriend in her room in his apartment. This is resolved when Daphne, quite implausibly, decides to claim that the man is actually incapable of having sex, so they're not doing it. Frasier accepts the explanation, but the subtext is very clearly that she's offering him an explanation he can accept in his mind, even though he knows it's not really true, so that he can stop worrying about it.

* ''Evanescence's'' [[http://www.youtube.com/watch?v=hHxHSoHOnZ8 Anything for You]], where the protagonist claims to believe any lies her lover make (in spite of knowing they are lies).
* "Paths of Glory" by FaithNoMore uses the line "I'm not afraid / But I'm afraid" to demonstrate a mentality frequent in WarIsHell scenarios: living in very obvious and unavoidable fear while at the same time attempting to adopt the {{Badass}} mentality that one isn't in order to cope with the twisted soldier fantasy/reality paradox.

* In ''ComicStrip/BeetleBailey'', Plato invokes this trope as a demonstration of how an officer's mind works by handing [[YesMan Lt. Fuzz]] a black paper and lying that the General said it was white, but... This prompts Fuzz to go on a rant about how you shouldn't question your superiors and how it all may be of vital importance somehow and culminating with his holding up the black paper and declaring firmly that it is white. The General happens to be passing and, without looking particularly surprised, just thinks he's nuts.

* In ''TabletopGame/MageTheAscension'', the entire universe ran on this trope. The laws of nature are subjective, so you can bend them in any way you make yourself believe is true. ''However'', you have against you not only your own preconceptions of reality, but also everyone else's views of reality. If you abandon consensual reality in favor of your own, you become an insane Marauder. Thus, you need to live in two very different universes simultaneously, believe in your own reality as well as the reality imposed by mainstream civilization. One group of Mages, the "Void Engineers", are notoriously bad at this. Their style of Magic is like being a ''StarWars'' Jedi as well as a ''Franchise/StarTrek'' TechnoBabble engineer who can solve any problem by ReversePolarity, and they keep forgetting that technology doesn't work like that in RealLife. To avoid going off the deep end, they have little computers constantly reminding them to treat the mainstream laws of nature with a minimum of politeness. No lightsabers in public places!
* Other games in the ''TabletopGame/OldWorldOfDarkness'' also contained certain vampire disciplines and maybe wraith arcanoi that allowed people to manipulate themselves in this way, securing them against mind-reading et cetera. (''Most'' countermeasures against mindreading was merely mental shields or masks, however.)
* ''TabletopGame/GeniusTheTransgression'' has the Phenomenologists, a MadScientist Splat based on a [[IRejectYourReality rejection]] of [[SarcasmMode silly outdated concepts]] like "[[ClapYourHandsIfYouBelieve truth]]" and "[[InsaneTrollLogic logic]]". Their special ability allows them to [[ConsummateLiar automatically succeed on Subterfuge checks]], since they always [[BelievingTheirOwnLies Believe Their Own Lies]].

* In the video game adaptation of ''VideoGame/TheHitchhikersGuideToTheGalaxy'', "intelligence" is defined as the ability to do this, and the only way to enter Marvin's room is to demonstrate that you have intelligence. [[spoiler: Appropriately enough, you ultimately accomplish this by physically removing your common sense, allowing you to carry "tea" and "no tea" at the same time.]]
* Implied for the BigBad in MightAndMagic VIII. He starts his conversation with you by lamenting the fact that his underestimation of your people led to him being forced to destroy your world needlessly, outright telling you that he doesn't ''want'' to, but his programming leaves him no choice but to continue. He ''ends'' it by blatantly giving you hints about where to go and what to do without actually admitting that is what he is doing, and then giving you an object, telling you that since you are so unimportant and weak people, and don't know what it is or what to do with it anyway, he can safely give it to you without compromising his mission.
* The Prophet of Truth from ''{{Halo}}'' could fall under this trope. He knows that the Covenant's religious tenants are wrong, but continues to believe in them anyway (the parts that are convenient anyway).

* In TheVerse of ''ComicBook/ChickTracts'', fundamentalist Christianity is not only true, but a very [[EasyEvangelism obvious]] truth. Some characters who understand this at heart still chose to not believe in it, instead embracing whatever false teachings that will be good for their career and social life. In some cases this is merely playing along with the lies, but in others they appear to honestly believe in them.
* Parodied (not the concept itself but its presence in a certain context) in ''Webcomic/SaturdayMorningBreakfastCereal'': [[http://www.smbc-comics.com/index.php?db=comics&id=2221]]
* ''Webcomic/TheOrderOfTheStick'' has Elan genuinely shocked that his EvilTwin survived - even though his GenreSavvy skills meant that he knew his brother wouldn't be killed off screen - because he ''also'' knew that he, as the hero, should be shocked by the revelation.
-->'''Nale:''' I think I'm giving myself a migraine trying to understand the level of wilful ignorance that requires!
** Though, considering that Elan's response to Nale's migraine is "First blood, Elan," he ''might'' have said this to screw with Nale.

* ZinniaJones's [[http://www.youtube.com/watch?v=CNcWdV0LYG4 episode on Pascal's Wager]], briefly argues the potential benefits of believing in different religions separately from each other but simultaneously.
* A necessary skill to develop for anyone living in [[Podcast/WelcomeToNightVale Night Vale]]. The show's narrator, Cecil, certainly seems to engage in it, though the degree to which he truly believes the contradictory things he says is difficult to determine.
* Two tropes, ThereAreNoGirlsOnTheInternet and MostFanficWritersAreGirls, are able to exist simultaneously probably because of this trope.

* A cornerstone tenet of the Church of the [=SubGenius=] is to "pull the wool over your own eyes" -- if you're going to believe in bullshit, it better be ''your own'' bullshit. One mark of a [=SubGenius=] sermon is that it {{Lampshades}} its absurdity while preaching it with the most sincere conviction.
* Medieval European theologians, prior to and during the thirteenth century, sometimes articulated the doctrine of the "double truth" (veritas duplex) to explain how their authoritative Scriptures sometimes said one thing but the works of authoritative Classical science (Neoplatonic works before the late Twelfth Century, and Aristotle's natural philosophy thereafter) pointed to another. Proponents of the double truth would claim that both versions were true according to their own sphere - philosophy or theology - and reconciling them was both impossible and unnecessary. The last great proponent of this doctrine was Sigier of Brabant, and it was thoroughly rejected by scholars in the Latin world from Aquinas onward, thanks to increasing familiarity with and borrowings from Aristotelian logic.
* A rare "good" use of this trope can be found in Creator/{{Orson Scott Card}}'s ''How to Write Science Fiction and Fantasy''. He posits that when considering one's own work, a writer must be able to believe that it is both the greatest work in the history of the written word and a terrible piece of garbage, simultaneously if possible. That way, one can believe the first while writing it, the second while editing it, the first again while submitting it for publication, and the second again if a rejection slip comes.
* A frequent attribute of {{narcissist}}s, [[TheSociopath sociopaths]] and other such personality types, particularly those involved in crime or deviancy. Its also the reason ThePerryMasonMethod is rarely effective in the real world- most criminals (or simply liars, bullies etc.), especially hardened criminals- rarely ever crack or confess to a crime even in the face of overwhelming evidence, refusing to admit any wrongdoing either because of delusions of their own infallibility or because total denial is how most innocent people would react and BelievingYourOwnLies seems like a good way of avoiding jail or garnering sympathy.
* Quite a lot of "common sense" beliefs contradict other "common sense" beliefs. [[http://beebo.org/smackerels/contradictory-proverbs.html Here are some examples.]]
** Stereotypes too, as noted on their trope pages - AllWomenAreLustful vs AllWomenArePrudes would be just one example. It's safe to say that everyone does this to at least some extent.
** Similarly, this is quite common anywhere strong opinions are found, such as politics, where people who embrace a particular principle on one issue will embrace the opposite principle on another. [[RuleOfCautiousEditingJudgement No examples are needed.]]