We'd say that Daryl and Wanda are demonstrating the trope, but we know that you already know that.
Captain Amazing: I knew you couldn't change. Casanova Frankenstein: I knew you'd know that. Captain Amazing: Oh, I know. And I knew you'd know I'd know you knew. Casanova Frankenstein: But I didn't. I only knew that you'd know that I knew. Did you know that? Captain Amazing:(clears throat) ... Of course.
Paranoia can be a funny thing. It seems no matter how well you've prepared or how you anticipate possible outcomes, there's always someone who can mess your plan up if he knows about it. Ah, but how do you know he knows? He may be acting like he doesn't know so you won't do anything different that he can't predict. This, inevitably, leads to the following paranoid rant:
"Yes, but if he knows I know he knows, he may do (X) instead. But what if he knows more than I think he does? He could be acting like he only knows that I know he knows, when in fact he knows that I know he knows I know he knows!"
Typical punchline: "...what was I doing again?"note Extra punchline: "I don't know."
Something of an overblown version of the classic chess axiom "think three moves ahead", this is one of the most common sights in a duel of Chessmasters. A Gambit Roulette may also have them, as the level of paranoia necessary to pull one off suggests he's suspecting everyone of knowing and reacting accordingly. Of course, if there's a Gambit Pileup in the making, that attitude might be justified...
May not feature the exact line, but often uses a scene where one character or the other remarks on how his opponent would react if he knew, and what he's doing in case that happens. In Real Life, humans are capable of keeping track of many degrees of what people know ("I know that he knows that she knows that they know that we know about the party..."), though even when taking the game seriously, they tend to find the string of "knowing" comical.
I Know You Know I Know breaks down logically, and it obeys some rules. Here are the levels of deception, with examples:
Level 0: absolute honesty, no deception.
Level 1: X plays level 1 (hereafter abbreviated X(n)). X(1) has information that Y(0) does not, and utilizes this in a deception.
Level 2: Y(2) knows that X(1) is playing a deception. Y(2) reacts accordingly.
Level 3: X(3) knows that Y(2) is well aware of the deception, and thus plans for the outcome of the first deception being revealed.
Level 4: Y(4) is aware of the above play, and knows that the logical reaction to finding out the deception will play right into X(3)'s hands. Thus, Y(4) plays around X(3).
Level 5: X(5)'s entire deception is a deception, maybe meant only to engage Y(4).
And so on, and so on.
This chain can go on indefinitely. In the really hairy cases, one or more deceptions are being played parallel or maybe even in conjunction with one another, making the above-mentioned Gambit Pileup.
From the second level on, the recipient of the deception (in this case Y) has two choices: either Y plays a counter-game so that the deception is revealed, or Y willingly plays the deception to X's logical conclusion. The first option will reveal Y to be playing a higher level, but will foil X's deception. The second option will let X fulfill the deception, but will not reveal Y's level. Reaction from Y is crucial, as this separates Y from a player of equal level to X. If that was the case, Y would simply be aware of the deception but unable to act upon it. In reacting, Y steps it up a level.
Of course, with each rise in level, the below levels become meaningless, so this gambit only works if X is not playing an even higher level, in which case Y would either be playing into X's hands or letting X win.
X also runs the risk of misjudging Y's level. If Y is playing a higher level than anticipated, then the deception is, as mentioned above, meaningless. If Y is playing a lower level, then X will be Crazy-Prepared but never engaged on the higher levels, which may leave X Properly Paranoid.
See also most instances of the Poisoned Chalice Switcheroo. Frequently a consideration in Feed the Mole. In many an Absurdly High-Stakes Game this will take the form a (often internal) monolog. Sometimes circumvented by making a completely random, unrelated, or unexpected move, which is where the Indy Ploy might come in handy.
Usually results in an Overly Long Gag. Frequently ends with an "I Didn't See That Coming". May result in Archive Binge-like behavior when plans are laid for both eventualities, and then for both of those eventualities, and then all four of those, and then all sixteen... This may develop into a Gambit Roulette if it hasn't done so already.
Not to be confused with "I Know I Know I Know" or the theme song to Psych.
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Anime & Manga
One episode of Yu-Gi-Oh! does this word-for-word, during Joey's battle with Yugi. He gives a long internal monologue about whether or not the card Yugi placed down was a trap card or if that was too obvious...
"Aw, forget it, I'm just gonna attack."
This exact scenario, with whatever permutations, has gone on in in the mind of every person who has played the game in real life, at least once.
Any duel involving Crow becomes this for his opponent, sometimes because he makes it a point to flaunt his foolproof strategy (which actually works) and sometimes because his opponents think too much.
Neon Genesis Evangelion is based around this trope — Gendo Ikari's relation with SEELE for instance. They each know that the other is planning to betray them, so both work with that, but both know that the other knows. They just keep on trying to get one step ahead using their unimportant pawns, such as Shinji, Rei, Asuka, Toji, Kaworu etc. Both are surprised when one of their pawns (Rei) decides to end the world rather spectacularily in favor of another pawn. So all the planning failed. Suckers.
Every fight during the second part of JoJo's Bizarre Adventure follows this pattern. Jojo attacks, the opponent declares they saw it coming and counters, Jojo explains he saw that coming and twists the attack as needed, and so on until one side or the other goes down. This carries over to later parts of the series — For example: Jotaro "faking" his genuine ability to move through stopped time so that Dio would be caught off-guard after calling him on his apparent bluff.
This makes up about a third of Kaiji, the other two-thirds being basic game theory and heroic determination. In particular, the defeat of Tonegawa in the first season is based on Kaiji's realization of when Tonegawa will stop knowing he knows. Tonegawa's observant enough to notice that two of Kaiji's cards are bloodstained on the back, and clever enough to realize that Kaiji has to know the cards are bloodstained. From there, Tonegawa assumes that Kaiji set a simple trap, bloodstaining cards other than the ones Tonegawa thought he had out, so as to trick him into playing the wrong card and losing. But because Tonegawa thinks he's better and smarter than lower-class gamblers like Kaiji, it doesn't occur to him that Kaiji would realize that Tonegawa would realize this, and that the cards are exactly the ones he initially thought they were.
Appears in Ghost in the Shell: Stand Alone Complex, strangely not as a part of an Evil Plan, but in a sniper duel. In fact, the whole episode revolves around knowing and predicting enemy tactics. The story is told by one character during a poker game to illustrate to the other players why he is so good at bluffing.
This is ALL of Spiral once the Blade Children storyline starts.
And all of Death Note from the time L shows up. So, all of it, really. It might as well be called I Know You Know I Know: The Manga Series.
Especially when L and Light start working together to catch Kira, who is actually Light. L was always slightly better at the up close and personal mindgames, but Light fared better in the end.
The series finale may be the largest example of this anywhere. Light and Near are somewhere around eight deep into this, both of them believing that they are one step ahead of the other. There's an entertaining panel in the manga where other characters witnessing a conversation between Light and Near begin to wonder why neither of them is saying anything.
The third round in Liar Game becomes this with Akiyama and Yokoya. The fourth round features it even more.
Most of the point of Legend of Galactic Heroes is like this, with Yang Wenli and Reinhard (and various other pairs) making plans, which may include knowing their opponent's plans (and sometimes involve a plan being an opponent seeing though the plan, with an extra layer of fake planning below it).
Eyeshield 21 does something like this during the big game between Ojou and Deimon during the Fall Tournament, with a whole string of characters reacting with shock, then going "Is that what you expected me to say?" when a dramatic play seems to go one way, then the other.
A major plot point of a certain Spice and Wolf arc. Holo is a semi-deity, one incredibly adept at quick thinking and long term planning both. Her sharp senses and silver tongue can turn practically any bargain into an incredible deal. So when Lawrence manages to find himself in a make-or-break financial showdown with Amati, (who is also an incredible merchant), he almost breaks down trying to out-think their combined plans. Holo was actually helping him the whole time, he was just so distraught over the matter that he missed the hints she was dropping, and completely misinterpreted the few he caught.
An episode of Pokémon had the group seeing a basket of fruit on the road. Ash wanted to eat it, but Misty points out that it's an obvious trap by Team Rocket. She then points to some fruit growing in the trees, which the gang decided to take... causing them to fall right into a trap set by Team Rocket, who set up the basket knowing it would be ignored.
Mirai Nikki Considering it's a series that's about people trying to kill each other to become God where each and every one of them can predict the future this happens often.
In the "Little Army" prequel manga of Girls und Panzer, Miho knows that the StuG III her sister Maho is commanding in their practice battle against each other doesn't have a rotating turret, but she's aware that Maho knows she knows this. Maho then plans on setting an ambush, but Miho plans to ambush Maho first, which results in Maho taking the initiative and almost taking out Miho's tank. The battle ultimately concludes in a final exchange of shells, resulting in Maho just barely winning.
Ravages Of Time runs on this trope. One strategist would lay out a plan, and in the end would say, "Of course, if the enemy strategist is any good, he would know that I will be planning this, so...".
Chapter 177 plays this up to at leastfifteenlayers deep. Zhang Fei and Chen Gong were scheming against each other; the former was trying to lure Lu Bu to Xiapi to kill him while the latter wish to drive out Zhang Fei to take Xiapi. Both of them outlines their plans, and the narrative switch back and forth between them anticipating each other.
According to Pang Tong, the ultimate strategy is to "Let your opponent know your next step. Even more brilliant is to let your opponent know your next two steps." (And then, the next three...)
In Log Horizon, there's a fair amount of this going on when the Eastal Alliance approaches the Round Table Conference for help against the goblin armies. Eastal desperately needs the Adventurers' superior military abilities, but they don't want to appear vulnerable, lest they make themselves out to be weak. The Round Table Conference, meanwhile, wants to help but don't want to make it seem like they are subservient or inferior to Eastal, lest the Eastal nobility think they can order the Adventurers around whenever they want. And of course, each side of the discussion is aware of the other side's agenda, and the fact that the other side knows their agenda. What follows is a complex and delicate battle of Verbal Judo between the two powers as they try to be allies while saving face.
Proper poker strategy, especially at higher levels, requires this kind of thinking and trying to stay one step ahead of your opponent(s). At its highest levels, the whole thing can get ridiculous, break down, and require game theory to come up with an ideal solution.
Blackjack strategy (eg, "counting cards") and trying not to let casinos notice you thinking too much is a meta-gambling example which can, at its extreme, surpass anything you've read in a spy novel.
Trading card games can have a variety of rules, exceptions, and so on to keep things interesting, but Yu-Gi-Oh! is well-known for the numerous and sometimes surprising ways the action can be altered, and the official rules tell you to expect this by saying that if a card says something contrary to the rules, you follow the card. There are cards to alter almost any aspect of the game: from draw to battle to endgame, so any action you take can begin this kind of mindgame.
The simple game "Rock-Scissors-Paper" tends to make for use of this trope to absurd degrees,all in simply figuring out what out of three moves your opponent will play.
Peanuts has used this joke quite a few times, when Charlie Brown is on the pitcher's mount, trying to figure out whether the hitter is expecting his fast ball. There was another incident involving Lucy's football-pulling stunt:
Charlie Brown: Ha! I know what she's got on her mind! Every year she pulls the same trick on me... she jerks the ball away just as I try to kick it... Well, this time I think she has a different idea. I think she's going to try to fool me by not jerking the ball away! This time she knows I know she knows that I know she knows I know what she's going to do... I'm way ahead of her! (Hilarity Ensues) Lucy: I figured you knew that I knew you knew I knew that you knew I knew you knew, so I had to jerk it away!
When Black Widow stops the hijacking of a NASA space shuttle she and the agent in charge of the hijacking keep one-upping the other after they reveal a part of their scheme to the other, each explaining how it "changes the game." First, Black Widow reveals that she is working with the CIA and has been impersonating the man's partner. The man, commenting that that changes the game, explains that he has just detonated the explosive in his partner's head, probably killing a few of his interrogators. Widow, saying that that changes the game, explains that she is still going to take this man in for questioning, though now she will make sure to hurt him while doing so. The hijacker, after commenting that that changes the game, explains that he is now crashing the shuttle to stop her. After that the game stops changing and Widow just beats the tar out of the man, but you have to wonder what game they started with and what they were playing when they finished.
Garfield had a case of this, when Garfield was trying to get a spider to come a bit closer so he could hit him with a (not very well concealed) newspaper. After a pileup of "Make me Make you"s, they forget what they were talking about... and the process was restarted in the last panel.
The Warhammer 40K comic Damnation Crusade has two Black Templars discover that the Chaos forces have run off despite not being particularly close to defeat, leaving behind heavy weapons and vehicles of great strategic value. One wonders why they ran off, the other thinks it's a trap, the first wonders if that's what the Chaos commanders want them to think, etc.
In Harry Potter and the Methods of Rationality, Harry learns methods of deception at higher levels, such that this becomes invoked. If you want to pretend that you do (or don't) know something, then instead of acting the way that you would if you really knew, you have to act the way that you think they think you would act if you really did (or didn't) know. You can fool a simple person by pretending you know everything and then subtly fishing for clues. And you can make them think you don't know anything, by making an obvious show of fishing for clues. But you have to anticipate that a higher level player could realise that you're only pretending to bluff, when in fact you really did know all along.
Harry successfully pulls this off in his first interaction with Lucius Malfoy, quite possibly by accident. When Lucius makes veiled references, Harry responds by playing along... badly. His deception is so obvious that Lucius sees through it almost immediately. Then Lucius starts to think it was too easy - Harry must have been only pretending to be a fool that pretended to understand. He says as much, and walks away, apparently confident that his original message was conveyed. Meanwhile, Harry doesn't have the faintest clue what's going on.
His new friend Draco's response to this? Screaming horror.
Played with in My Immortal. When Ebony Enoby travels back in time, she knows that Snape Snoop possessed James Samaro and made him kill Lucious Lucian. She, however, did not "want them to know [she] knew." Whether or not Tom knew she knew is not made clear, but it is likely, as he is Volxemort and commanded Snop. "Suddenly it's a sitcom," the dramatic reading snarked at this bit.
Tom knew she knew that he knew that Snoop worked for Volxemort and possessed Samaro and... it kind of melts from there.
In a recent chapter of Dragon Age The Crown Of Thorns, Theron Mahariel, the Dalish Elf Warden, contemplates how he's been passively spying / been allowed to eavesdrop on some secret talks between the Guile Hero dwarven noble protagonist and Alim Surana, One-Man Army mage. The extent of the I know he knows I don't, etc., has to be seen to be believed. And it's only slightly played for laughs.
So, basically, Theron knew that Raonar and Alim knew some things they didn't, and he also knew that Raonar knew that he knew this, but did not bother pointing it out or taking measures to prevent the tattooed elf, in the future, from coming to know of everything else Alim came to know, as long as said mage did not come to know of the hunter's knowing of what he thought everyone else did not know, meaning that Theron did not have to bother getting into the habit of finding lounging spots any way farther, since Raonar either did not have anything specifically against it or knew he was not going to inform the others of his knowing that Alim, who did not know that he knew of his knowing of things that only Raonar knew more about, knew more than what he thought he knew the others did.
Theron had continued to not-truly-eavesdrop on them occasionally, wondering when the crooked dwarf would come forth and inform Alim that, despite what he thought he knew, what he really knew was less than he believed, considering that he thought he knew for sure that no one besides the commander knew what he knew, and that, by extension, no one else knew he knew of those things, when in fact Theron had always known them without his knowing, Alim having been prevented from coming to know that the Dalish elf had always known of his knowing, as well as of Raonar's knowing that the latter knew whatever Alim knew of what he believed only the two of them knew, plus that Alim did not, in fact, know that Theron knew of his supposed knowing that no one besides the exile knew of his knowing of those things (a conviction which was false).
In Wreaking Havoc! Harry and Daphne Greengrass had a somewhat convoluted exchange concerning Nicholas Flamel.
Daphne: What do you know that he knows and suspects that you know? Harry: I suspect that he knows what I need to know and that I know that he suspects that I suspect he knows what it is that I need to know.
Light: Maybe if you told me what you were planning ahead of time...
Near: But I thought you would know what I was planning and plan around it and then I'd plan around your plans in a way you'd never see coming...
Films — Animation
Disney's Hercules has a variation. Hades is telling The Fates his Evil Plan, but they keep interrupting him by saying they already know his plan, because they're the Fates and they know everything. Hades eventually snaps and shouts ''I KNOW you know! I know! I get it! I get the concept!"
Films — Live-Action
The Princess Bride has this between Vizzini and the Man in Black, as he attempts to figure out which goblet contains the poison. (See the Literature entry below.) Subverted in that Vizzini isn't really trying to reason it out; he's just throwing possibilities at the Man in Black to see if any of them gets a reaction. If he were really playing I Know You Know I Know, he'd have realized that just as he wasn't about to leave the outcome to chance, the Man in Black wasn't about to leave it to chance either...
If Vizzini were paying attention to his own line of reasoning, he might have realized that he was getting dangerously close to the truth (as shown by the Man in Black getting increasingly nervous in this scene in the book) that neither goblet was safe to drink from.
Monkeyed around with in Mystery Men; see the page quote.
The Swedish movie The Shark Who Knew Too Much opens with the main lead chased by a helicopter while shouting this sort of dialogue. Given that he's spent his whole life masquerading as a group of identical triplets who can't stand each other's presence just to trick his father into giving him shareholder majority of the company, it's obvious there's a lot of deception involved.
In Sneakers, Martin is interrupted while breaking into an office. In the course of inventing a plausible explanation for why he's there, he finds himself inadvertently entangled in one of these:
Martin: And never let him know that you know what he thinks you don't know you know... y'know?
and give him he— he...lp.
Give him head?! — Be a beacon?!
The villain of Under Siege 2 Dark Territory does this while explaining to the muscle of the operation that he's going to demonstrate the power of his earthquake-shooting satellite by using it on a fertilizer plant in China: "[The fertilizer plant] is actually a secret chemical weapons testing facility. We know this. The Chinese know that we know. However, we pretend we don't know, and they pretend they don't know that we know that they know we know. But know that we know. In the end, everyone knows."
Inverted in a long-distance sort of way in We Were Soldiers, where throughout the entire battle, Colonel Hal Moore emphatically knew what his Vietnamese counterpart was going to try, whereas the Vietnamese CO emphatically did not.
Specifically because the Vietnamese were using more or less standard tactics, and Moore, using a never-before-testing air cavalry method, was forced to make up tactics as he went along.
"As I said before, I've allowed you to keep your wicked life for two reasons. And the second reason is so you can tell him [Bill] in person everything that happened here tonight. I want him to witness the extent of my mercy by witnessing your deformed body. I want you to tell him all the information you just told me. I want him to know what I know. I want him to know I want him to know. And I want them all to know they'll all soon be as dead as O-Ren.
Hot Lead and Cold Feet has Don Knotts' Sheriff deliver this line regarding his arch-nemesis, Rattlesnake: "'Cause he's here and I know he's here. And he knows I know he's here! But he doesn't know I know he knows I know he's here, but I know. So I got the edge!"
White Goodman: Cuz I know you. And you know you. And I know that you know that I know that you know you.
Of course, Goodman is an established blithering idiot, so the scene itself is a parody, but the character thinks he's playing it straight.
From the description above, the classic quasi-comedy The Court Jester. Everyone knows the pellet with the poison's in the flagon with the dragon, but the vessel with the pestle has the brew that is true!
Bob the Turk: I warn you, do not make me do something that I would not do, unless someone made me do it because they didn't do something someone told them to do. Gus Cardinale: Don't worry, Bob, I would never do something to make someone do something to someone, because that someone didn't do something that someone wanted them to do. Bob the Turk: I'm glad we understand each other. Gus Cardinale: ... Me too. (cue Aside Glance)
From the Harry PotterAlternate DVD CommentaryGag DubWizard People, Dear Readers: "Then, dear readers, Harry notices a tear in Snake's pants and blood all over her leg, and Snake notices that Harry has noticed, and he notices she noticed that! I mean, there is a trade of noticing going on that is just bewildering."
Played with hilariously by Professor Hilbert in Stranger Than Fiction, when Harold mentions his narrator said "Little did he know":
I've written papers on "Little did he know." I've taught classes on "Little did he know." I once gave an entire seminar based upon "Little did he know." Sonofabitch, Harold. "Little did he know" means there's something he did not know. That means there's something you don't know. Did you know that?
In the film (and play) Romanoff and Juliet, The General (Peter Ustinov) goes back and forth between the U.S. and Soviet ambassadors, discovering the layers of intrigue: The Soviets have broken the American code. The Americans know this, and are feeding the Soviets misinformation. The Soviets are aware that it is misinformation and are pretending to be fooled by it. When the U.S. ambassador hears that, he is flabbergasted.
From Little Big Man comes the great quote "You want me to think that you don't want me to go down there, but the subtle truth is you really *don't* want me to go down there!"
Down with Love, several times, one of them also counting as a Hurricane of Puns, as the discussion concerns two magazines called "Know Magazine" and "Now magazine"
Barbara Novak: You know I have no interest in seeing you.
Catcher Block: But you know you have to, and you know I know you have to. I'm sure you know how things are at KNOW ever since your new NOW.
Barbara Novak: I have no way of knowing how things are now at KNOW. I knew how things were at KNOW before NOW.
Catcher Block: Then you should know now at KNOW things are a lot like they are at NOW; we have to interview every applicant for every job, and so do you or you'd be going against NOW's definition of discrimination and you wouldn't want the readers of NOW or KNOW to know that, now would you?
Barbara Novak: Scooped you again.
Catcher Block: I knew you would.
Barbara Novak: I knew the minute I placed an ad as an equal-oportunity employer, you would be the first to apply.
Catcher Block: And I knew you knew and you'd let me in to ask you to marry me.
Barbara Novak:But you didn't know I'd say yes!
And Barbara's entire speech at the end where she reveals that she knew everything that happened in the movie would happen and planned the entire plot accordingly.
Akeem: Listen, I know what I like, and I know you know what I like, because you were trained to know what I like, but I would like to know, what do you like?
Seen in The Three Musketeers (2011). The musketeers have to break into the Tower of London. Milady, who's worked with them in the past, knows their methods, and can give Buckingham the information. They know she knows their methods and will tell Buckingham. She knows they know she knows and will tell Buckingham. The English capture D'Artagnan, who she knew they'd use to infiltrate while the others acted as decoys, assuming she wouldn't take him into account. Turns out, they knew she'd do that, he's the decoy, and they do something completely different.
An old joke, recounted in ''The Big Book of Jewish Humor, involves a merchant seeing his rival getting off a train, and asking him where he's just come from. "From Minsk," the rival replies. "Aha!" cries the first; "you are just saying that because you want me to believe that you have really just come from Pinsk!note Minsk-and-Pinsk jokes were a staple of nineteenth century Jewish humor in Russia But I already knew that you really have just come from Minsk. So why are you lying to me?"
A hilarious example exists in The Princess Bride with mid-level villain Vizzini. He goes through all sorts of permutations on which goblet has the poison in it, based on his observations and the defeat of his minions. In the end, he was right in all his deductions, as every conclusion he reached was that he could not choose one of the two goblets, but he failed to take his deductions to the logical conclusion: his opponent had poisoned both goblets of wine. His opponent had spent four years building up an immunity to that particular poison.
The Dune series is renowned for its incredibly intricate layers-upon-layers of this kind of gambit.
The first book alone features a subverted Red Herring Mole (someone suspected of being a traitor who is both too obvious to be the real mole as well as Beneath Suspicion, but actually turns out to be the traitor), followed by an elaborate mind game played by Thufir Hawat to set the Harkonnens against one another, and capped with Paul successfully bluffing and counter-bluffing the combined forces of the Bene Gesserit, the Imperium, and the Spacing Guild.
Dune Messiah continues the pattern, only this time it's Paul's enemies pulling a The Plan aimed at forcing him to choose between his beloved and his Imperium. He knows they are doing this, but falls into the trap anyway, only to be rescued from it by the son who will later replace him as the most powerful prophet in the universe.
Children of Dune sets up a three or four-way struggle for control of the Imperium, with the demon-possessed Alia on one side, the Bene Gesserit on another, the remnants of the Corrinos as a third, and an unknown quantity in the form of Paul's children, Leto and Ghanima. Leto is captured by people whom he believes to be working for the Bene Gesserit, only to have it turn out that Alia is secretly calling the shots. He himself, however has a deeper plan that eventually trumps all of theirs and renders them moot.
Parodied mercilessly in the National Lampoon's Doon, where two characters have a half-hour long conversation without knowing what the other is talking about.
Characters in the Lymond Chronicles are prone this. A particularly risible example is in The Game Of Kings, where Lymond, who is trying to help the Scottish forces, and knows his brother will disbelieve anything he says, LIES to him about the English intentions, knowing Richard will conclude the opposite.
Edgar Allan Poe plays this one straight in one of his mystery stories, "The Purloined Letter". Private eye Auguste Dupin actually explains that this is the reason he can outwit the police and get his man. The police know who stole the document; the thief knows the police know. The difference between Dupin and the police is that Dupin knows the suspect knows the police know, and the police don't know that.
Vetinari plays a subtle form of this game off-screen in Discworld. His mail packets to and from Uberwald are always clearly tampered with, and his semaphore transmissions are always intercepted. This is all as expected, and he encrypts his communiques with codes that are almost but not quite unbreakable. He could come up with a cypher no one else on the Disc could break, but that would be far less useful. This way, only his most resourceful rivals (specifically, Lady Margolotta) can read his messages, and then he knows exactly what they think he knows.
In Timothy Zahn's The Thrawn Trilogy (Star Wars Expanded Universe books), part of Magnificent Bastard Thrawn's effectiveness in battle is based on his reputation: his enemies know fully well he's a a nigh-unparalleled master strategist and tactician, so from their perspective each and every move he makes is like Schrodinger's Gambit, existing in a state of It's A Trap and It's Not A Trap until they open the box and the waveform collapses.
The climax of the third book brings this to an epic level. Thrawn knows that the New Republic wants to capture an important bit of technology, of which only three are known to exist, all on Imperial worlds. The New Republic knows that Thrawn knows this. They also know that one system is heavily protected while another is only lightly defended. Thrawn knows that they know this. The New Republic knows that Imperial Intelligence is very good and will pick up disinformation that shows an attack on the lightly protected system is in the works. Meanwhile they actually plan to attack the heavily-fortified one. Thrawn knows that the New Republic knows that his intelligence is that good, and that the "secret plans" are a deception, so he disregards those attack plans and prepares for the real attack.
In the Hand of Thrawn Duology, set a decade later, a trio of Imperials conspire very successfully to make it look like Thrawn is Back from the Dead. When Han Solo finally sees the (fake) Grand Admiral and has his suspicions deftly countered, it's a shock. Thrawn was, after all, alarmingly good at anticipating what people would do.
Han: From now on, we can't trust anything we see. Anything we see, anything we hear, anything we think we ought to do. Not with Thrawn back on the scene. Lando: Thrawn or no Thrawn, the Empire is still down to eight sectors. Maybe this is really all he's going for, hoping to confuse Coruscant so badly it just freezes up. Han: Who knows? That's what drives you so crazy about him. You try to do something and odds are it's exactly what he wanted you to do. You stand still and don't do anything, and he runs a smartrope around you.
Zhuge Liang is the master of this trope. Various plans include:
Empty City: Zhuge Liang sits alone in an empty city playing his harp while a rival army comes up. They know that Zhuge is a genius and is obviously up to something. Knowing they would know this, the city really is empty, and the whole thing was a stall tactic. That worked.
Two Roads: Cao Cao is leading his army through a mountain pass when he comes to a fork in the road, one direction he can see a lot of smoke as you would expect from army camp fires; down the other he sees very little smoke. Obviously, the big smoke path is a ruse and the little smoke path is an ambush. Actually? I Know You Know I Know, the big path is the real army.
In Rohmer's "President Fu Manchu", the object is to find the villain's New York base. The police reason that since Fu Manchu is such a wily mastermind, and the first place "anyone" would look for him is Chinatown, that is really the LAST place he will hide. Only Fu Manchu expects them to reason like that, and moves into Chinatown. Only Nayland Smith figures that is exactly what he will think.
Played with in Twilight. Edward and Alice Cullen play a chess game by using their abilities to figure out what move the other is going to make next... and countering... and being countered... and countering again... and so on.... The game is finished in their minds before two pieces are physically moved.
A children's book titled Finding Buck McHenry, about a man who may or may not be a retired pro baseball player, has the young narrator going, "I knew. And he knew that I knew. And I knew that he knew that I knew. Stop. You're making yourself dizzy." The story Mack Henry eventually tells is half true; he did play baseball as a young man, but he wasn't the same man the kids are confusing him with.
In Mistress of Dragons, Draconis knew that Edward knew that Draconis knew that Edward didn't trust him. I had to spend 5 minutes interpreting that.
In "Riding the Bullet", by Stephen King, the main character is on the verge of freaking out when he dizzies his own mind with how he can't let the dead guy next to him know that he knows that he knows that he's dead (or something, I'm quoting from memory).
Sometimes both parties can "win" at this (or at least, two out of three can). In one short story in Future on Ice (edited by Orson Scott Card), an immortal being finds two soldiers who're lost and starving to death, and it gives them each two boxes. It's observed them and claims it knows how they think, and if it predicted of one of them that he'd only open one box, it gave him food in one box, and in another box a device that will allow the user to become immortal if he so chooses. If it predicted one would open both boxes, one box will have food and the other will be empty. The Philosopher points out that no matter what the immortal thought, they lose nothing now from opening both boxes. The immortal predicted that he'd do this, but not that his comrade would listen to him, so said comrade is the only one to get an immortality device. The thing is, The Philosopher didn't want immortality, and he later figures out that the device in question actually disintegrates the user and creates an immortal copy.
In Neal Stephenson's Cryptonomicon, Detachment 2702 exists to generate enough random noise to cover up the fact that the Allies have broken German and Japanese ciphers. It stands to reason that if the Axis finds out, they'll switch to a new cipher, so being able to act on the information they got without revealing they have this information becomes very important. Partially Truth in Television; Detachment 2702 is fictitious, but using the information gained from broken codes without revealing that the codes were broken was a major concern for Allied Intelligence.
Discussed in the Belgariad. The Drasnian ambassador to Nyssa is bribing the staff of the Tolnedran embassy for information as part of his intelligence network. The Tolnedran ambassador knows this, and occasionally feeds his staff fake information as a result. The Drasnian ambassador knows this.
Silk: Does he know that you know? Ambassador: Yes, but I don't think that he's aware that I know that he knows that I know.
The BBC Doctor Who book The Doctor Trap has an entire plot based off this. The villain is convince the Doctor knows something the villain doesn't. Not really. The titular trap, the Doctor explains is what they think you know that they don't. Confused? Yeah, join everyone else in the book.
A Fourth Doctor book has the Doctor going on and on like this, until Sarah Jane Smith tells him to shut up.
Sarah: You know they're lying. Doctor: Of course I know. And they know that I know. And I know that they know, and they know that I know that they know [etc., etc.]
Subverted by Ephraim Kishon in a story with a bagel salesman. The narrator thinks he wants to fool him into buying lower quality bagels, and goes through lengths with this trope, only to find out at the end that all the bagels always were fresh, and he suspected an innocent guy lying.
The Gentleman Bastards first on-page job is engineering an elaborate Spanish Prisoner con involving a civil war and large amounts of valuable brandy. The Bastards then dress up as the local State Sec and bluntly tell the marks that the brandy salesman is running a con, that State Sec is investigating, and that if they just continue shelling out the money, they will be compensated and rewarded as soon as whoever is behind the con is caught. That the marks are now on level 2 means the Bastards no longer have to keep up the elaborate and expensive level 1 con.
The Changeover demonstrates a nonverbal example, as main character Laura had always been aware of Sorry's status as magical, with Sorry knowing that she knew.
In Michael Flynn's Spiral Arm novel In the Lion's Mouth, Silky Voice suggests telling Ravn the truth, because there's an advantage in that they would know she knew what they knew.
In the Magic: The Gathering novel Test Of Metal, Jace and Tezzeret play this game, each trying to anticipate the other's moves while knowing the other is doing the same thing and knowing the other knows this.
"Plugged" by Eoin Colfer: "He lied, and we both knew; what we didn't know was whether the other knew that we knew."
Played straight in the Known Space novel Protector. A superintelligent alien (sort of...) needs to fight a space battle with similarly intelligent aliens. He knows what the ideal weapon is for the circumstances—but also knows that the enemies would know what that ideal weapon is, and could use countermeasures. So instead, he comes up with four pretty-good weapons which would each require different countermeasures, and rolls a die to pick which one to use. (The enemies would be able to predict that he'd do that, too, but they wouldn't know which way the die came up.)
The first series in The Chronicles of Amber is about a large, immortal, royal family with the powers of demigods squabbling and scheming over the throne after the disappearance of their father. Being that they've had centuries worth of spying on one another, studying each other in an attempt to find and exploit any possible weaknesses, making and breaking alliances as soon as it's advantageous and so on, there's a lot of this going on.
In an episode of Friends, "The One Where Everyone Finds Out", Phoebe and Rachel find out about Monica and Chandler's secret relationship, and something of an arms race begins regarding whether or not "they know we know they know we know!" Joey gets caught in the middle (since he's known for a while), and eventually throws up his hands when he can't keep track of who knows what. When Rachel and Pheobe order him not to tell Chandler and Monica, he exclaims: "Couldn't if I wanted to!".
Parodied in the same episode, when Monica walks into the apartment and dramatically says, "They know." Cue the confusion.
Similar to the above example (but fewer levels), Richie in The Class must determine how Duncan's date went for Nicole, but since he's a Bad Liar, he ends up revealing Nicole's secret, then Duncan's secret, then both.
During Draft Day betting at Sports Night Dana and Casey try to figure out if the other knows anything about Tommy Castro's knees, and if so, do they know that the other person actually doesn't know anything about... etc. Ends when Casey explains the entire I Know You Know I Know situation to Dan, while wired so Dana can hear him.
The Doctor Who one-off comedy special The Curse of the Fatal Death has the Doctor and the Master engaging in a round of this. Since both have access to time machines, it quickly gets complicated.. ("624 years in a sodding sewer!")
Also in the regular series episode "Let's Kill Hitler", between the Doctor and River. Though it doesn't matter, because she's already poisoned him.
Sir Humphrey: Yes, but they don't know you probably wouldn't.
Hacker: They probably do.
Sir Humphrey: Yes, they probably know that you probably wouldn't, but they can't certainly know!
Hacker: They probably certainly know that I probably wouldn't.
Sir Humphrey: Yes, but even though they probably certainly know that you probably wouldn't, they can't certainly know that although you probably wouldn't there's no probability that you certainly would!
Used dramatically in Stargate Universe with Chloe revealing that she knows about the thing that he knows, it's just that... the 'thing'.. is Eli being in love with her whilst she's in love and in a relationship with one of Eli's best friends.
A common sight in Survivor, with the convoluted backstabbing, double-dealing, and mind-gaming that the players perpetrate on one another.
Relied on by Shawn in Psych, as it is unclear whether/how much most of the main cast believes his psychic stint. Lampshaded in the theme song, in fact, it's (almost) the name of the theme song.
It's also unclear who the "you" addressed in the lyrics "I know you know that I'm not telling the truth/I know you know you just don't have any proof" is. Lassiter? Vick? Jules? Henry? The audience?
Also, there have been some very high-stress or time-sensitive moments where Shawn doesn't even bother to try and make his psychic schtick look plausible in front of Vick, which implies that she operates on I'll Pretend I Didn't Hear That (plus her no-nonsense, down-to-earth persona makes her steadfast reliance on Shawn's vibes seem very out-of-place).
Played with in NCIS when Gibbs asks for Ziva's weapon. And her backup weapon (revolver in ankle holster). And her backup backup weapon (a knife). He then hands the knife back to her, and points out that he wanted her to know he knew.
Recently used in Chuck, after the staff of the buy more is told to behave Morgan goes through this to try and work out whether or not they should misbehave due to the person telling them knowing they'd know he knows they know he knows how they'd act.
Burn Notice talks about this during season 2. Michael, having started to become much more enlightened as to Carla's objectives and methods, begins to spy on her. Unfortunately, as he points out, he can't do anything different because it would clue her in to the fact that he already knows a little of what's going on.
On The A-Team, B.A. Baracus is terrified of flying, so they have to drug him every time they go on a flight. One time, they put it in his burger. Another time, he realized that they needed to drug him, so he took Murdock's burger. And promptly passed out afterwards. Finally, at one point he was switching everyone's burgers, trying to figure out which one was drugged, and ultimately decides that the one burger they wouldn't have put it in is the one they gave him first... only for it to be revealed that this time, they'd drugged his milk.
How exactly did this guy get into Army Special Forces again?
Amy: The last couple of times Decker got really close you pulled the same trick, hiding right under his nose. Making him think we're half-way out of state. He's gonna figure that game out. Hannibal: Yeah. But he'll figure I figured that, so he'll figure that I figured the other way, which is why we're staying here. Amy: That makes no sense. Hannibal: Decker will understand it.
In an episode of The Invisible Man (2000), Darien gets implanted a spy nanobot by a former girlfriend working for the evil agency Crysalis (the details of how the nanobot was implanted are a bit embarrassing to him). The Agency finds out, so they Know that Crysalis know. So they plan to use him as a decoy, but later the secret is ruined, so Crysalis knows that the agency knows that Crysalis knows. And obviously, the Agency knows.
Used mostly seriously on Studio 60 on the Sunset Strip. Matt's assistant has told Danny about Matt's pill-popping. After Danny confronts Matt, she quietly walks into the room.
Assistant: I know you know I told Danny. Matt: I know you know I know.
Shows up in Fringe with Milo Stanfield, a savant who can predict the future enough to cause accidents to kill people set off by dropping a pen. It's impossible for Fringe Division to outthink him, because if they try, he'll predict it, and if they predict he'll predict it and choose a different option, he'll predict that too. Astrid describes the situation with at least six recursions of "he'll predict that we predict". The ultimate solution comes when Olivia DOESN'T KNOW something she should have and it throws off his entire plan long enough to capture him.
Invoked in Sherlock's "A Study in Pink". The assassin tempts Sherlock into a battle of wits involving two identical pills: one poisoned, the other harmless. He tries to lure Sherlock in with this form of logic, but Sherlock refuses the terms of the argument, knowing that no matter what choice he makes, the odds of success are still 50/50. He takes a third option and is ready to walk away from the whole thing, but the assassin pulls a pistol on him and threatens to shoot if he doesn't choose. Sherlock then deduces what the other victims didn't, that the gun is a fake, but gets lured back to the table anyway because he has to know if he can win. And the twist of it is, the show never says if he made the right choice.
Played with on Boy Meets World. Cory thinks that Mr. Feeny knows that Topanga proposed to him, even though Mr. Feeny doesn't actually know:
Cory: Ohhhhh, you're a smug one aren't you George huh. You know you know, I know you know, I don't know how you know, but I know that you know.
Mr. Feeny: Alright I know, I know everything. Now what in the world are you talking about?
Cory: NOTHING!! THIS GETS OUT, I'LL HUNT YOU DOWN LIKE A DOG!!
Myka and H.G. have a good one in Warehouse 13 quickly becoming complex making Myka's partner tell them to stop a small part below
Myka: And, for the record, I knew that you slipped this in my pocket at the cemetery.
HG: I thought you’d know.
Myka: I knew that you’d think that.
Mission: Impossible episodes that pit the team against a rival intelligence agency often involve this as part of a Kansas City Shuffle. In one episode, Phelps pretended to be a traitor who sold the location of four key SAC bases to the Russians. But since the Russians figured out that he was really an American intelligence officer and not the agent employed by a burned Russian spy that he claimed to be, they knew that the locations he gave were where the Americans wanted the Russians to think the bases were, and thus disregarded the locations as fake. But Phelps knew that they knew this (And had in fact arranged for them to figure this out), which is why he gave them the real locations of the bases, thus ensuring that the Russians would never look in those cities for the bases ever again.
"Come to the Sunshine", a '60s sunshine-pop ditty written by cult favorite (and future Beach BoysSmile collaborator) Van Dyke Parks and recorded by Harpers Bizarre, has in its chorus the line You know, I know, you know, that I love you.
Otis Redding ad-libbing at the end of his Cover Version of Sam Cooke's "A Change Is Gonna Come": "you know and I know, you know that I know that I know that you know, honey, that a change is gonna come."
The Kursaal Flyers' aptly-named "Little does She Know" gleefully parodies this.
Little does she know that I know that she knows That I know she's two-timin' me
On an episode of Monday Night RAW, before a scheduled match with Triple H, Mick Foley's Dude Love and Mankind appeared on the screen to introduce Cactus Jack. (It was sort of a thing.) Towards the end, Dude Love asks Mankind if "you're thinking what I'm thinking," and Mankind cheerfully replies "I think I am thinking what you think I think you're thinking!"
New Japan Pro Wrestling's luck it was to present the feud between Prince Devitt and Low Ki, which was pretty much nothing but this, as highly analytical former partners with superficially similar styles. Hell, one of Low Ki's signature moves has become a feinted shining wizard, so he always has some Confusion Fu going on.
While nowhere near as high profile, all of Low Ki's face offs with Manik in TNA have been somewhat similar. Manik has an uncanny ability to predict just how Low Ki will try to counter his moves and acts accordingly, yet Low usually ends up a step ahead of Manik away.
Bob: Okay. I want you to listen very carefully and tell me if I've got this right. You're angry about what you think I said about what you said about what you thought I said (but we now both agree I didn't say) about what you thought I thought you thought about what I did when you did what you did when I didn't do what you thought I said I would do but what I thought I said I would try to do, is that right? Alice: Yes. Bob: Yeah I thought so. Well I didn't say that. Alice: Yes you did! You said you couldn't believe I said what I said about what I thought you said (but which we do agree you didn't say) because you thought I said I said what I said not because you didn't do what you said you'd do but because you said you'd do it, and that makes me feel that you feel that I feel that you don't feel what I feel. Bob: You know I feel you feel I feel what you feel. Alice: Yes but I don't feel you know I know that and that's why I said what I said. Bob: What did you say? Alice: That sometimes, I think you're a little over-analytical— Bob: Bollocks.
In baseball, when one team manages to figure out the second team's signals they'll usually try to only act on that knowledge at a critical point in the game. The second manager might intentionally allow them to try and steal the signal so at the critical point they think they know what's being planned. Which could cause paranoia in the first manager if the signal seemed too easy to steal, leading to suspicion of a setup. Which the second manager would know, so...
In another baseball example, catcher Carlton Fisk once managed to confuse a batter by talking about how he knew the batter knew the pitcher was ignoring Fisk and only throwing fastballs down the middle, and the pitcher knew Fisk knew the batter knew but wouldn't listen to when Fisk said he was signalling for curveballs (he was actually signalling for fastballs...down the middle). After an epic performance which included Fisk screaming at the pitcher to throw the curveball and going out to the mound, yelling and waving his arms around, the batter was so screwed up trying to figure out who knew what was supposed to happen he could only watch a third strike fastball go right down middle.
In Arsenic and Old Lace, the bluffing game regarding which characters know about the murders committed by the other characters reaches truly epic levels.
Jonathan Larson's semi-autobiographical musical, tick, tick... BOOM, contains a song called "Therapy". Essentially, the song is a dialogue between two characters detailing how, if they'd known that the other knew what they knew... things would be different. It's really quite brilliant.
What makes it even better is that, in the end, the other character is proven right. To make this clearer, "I feel bad that you feel bad about me feeling bad about you feeling bad about what I said about what you said about me not being able to share a feeling." Whatever it was that she said about him not being able to share a feeling was probably accurate; he apparently isn't good at it.
The Lion in Winter played this straight, albeit slightly lampshaded, complete with the line itself from Prince Geoffrey: "I know. You know I know. I know you know I know, we know that Henry knows and Henry knows we know it. We're a knowledgeable family."
When dealing with conspiratorial spy-types, it's always important to keep track of who knows what, and how they know it. City of Heroes plays with this by having the character knowingly sent into a trap, just to cause confusion among the enemy.
Indigo: ... So, they've decided to set a trap. However, I know that it's a trap, and I must assume that they know I know it's a trap. So really, it's more of an invitation. An invitation to ambush. Shall I send your RSVP?... Oh, and do play along some if you get the chance. That should really help to freak them out.
City of Heroes loves this, especially with scanner/newspaper missions. Villains (or heroes) will call out your character for a fight, set an ambush, and attempt to take you down. The fact that you know it's an ambush in no way deters you from walking right into it, but, in spite of insurmountable odds, you always eventually walk out too.
The Dinosaur King DS game descends into this sometimes with the hints that opponents give about their next move.
From the final mission of the Whiteboard War game Chop Raider: "We're not going to force you to do it, but we know you won't decline."
Subject 2: I know that you know what I'm thinking.
Subject 1: I know that you know that I know what you're thinking.
Subject 2: i know that you know that I know that you know what I'm thinking.
The new indie game Achron is built upon this trope and time-travel. Every minute or so, a time "wave" occurs so any changes you made to that last big fight will be etched into the game and your opponent will have a chance to fix it or leave it. Or maybe you just pretended to change it, and he sends troops back to fight what he thought you sent back. But then, you did send stuff back, but maybe not to there, so he doesn't know that you know that he knows you sent troops back. Or does he?
Fighting gamer and game designer David Sirlin calls it "Yomi Layers" with "I know you know I know" being the third layer. He explains it in-depth in this article.
The opponent is in the exact same situation because you could Take a Third Option: switch out yourself into say a Grass-type that could handle either Water or Ground (and other options exist, so unless all of the opponent's Pokemon have already been revealed, you never know what may be brought out next).
Rotation battles, giving you three pokemon and the ability to switch which one is in front and able to attack and be attacked in your turn, uses this even more so as your attack could end up hitting one of three pokemon and you never really know which one. This is naturally the best feature of the battle variety.
Platform Game: Any type of this game can have this trope come into play with various types of trap like the Pressure Plate trap or Kaizo Trap. One example is in Limbo, which has one a Pressure Plate trap, and then another right after. This leads to the I Know You Know I Know because any semi-competent Genre Savvy gamer is going to go "Well, it's obvious that the 2nd trap is an inverted version of the first... but wait.. if the designer knows that, he'll make the trap the opposite of the inversion, so I should do the same thing I did on the first trap.. but he knows that I know that.." this loops around until the player simply chooses one at random, and likely dies anyway.
Red vs. Blue has an example in the final episodes of Revelation: as Washington and co. approach a base known to be inhabited by Tex, he stops the jeep some distance away, pointing out that the open area ahead is the perfect spot for a sniper ambush. Doc asks, since Tex received the same training he did, wouldn't she know he'd know that and plan accordingly? Wash: "You're overthinking it." And then the buried landmines go off.
Mr. Square Has a prime example, wherein Mr. Square says, verbatim "I know that you know that I know what you know about knowing that I know, but you don't know that my knowledge of you knowing is not secret, I WANT you to know that I know so you don't know what I don't....you know?" in this comic
Quantum Cop: This Quantum Vector Collector will tell us exactly where Quantum Crook is. Quantum Crook: This Quantum Vector Collector Inspector will tell us when my opposite tries to find us. Quantum Cop: To avoid being snooped, I had you add a Quantum Vector Collector Inspector Detector. ... Quantum Cop: Excellent. He's in Mt. Fuji and doesn't know we're coming. Quantum Crook: Excellent. He knows where we are, and thinks we don't know he's coming.
A later look into his mind shows that Ocelot thinks like this all the time. He made a section of his mind labelled 'porn' just because he knew Mantis would suspect he was using that section to hide sensitive formation, and instead filled it with some rather depraved things. Raven lampshades it at that point.
He eventually states that his entire existence is based on this trope, which is what makes him both such an exceptional spy and a pain in the ass.
Mantis: I mean, you must spend every day pretending to act like you're falsely letting on that you aren't not unbetraying someone you don't not purport to alledgedly not work for but really do! How do you keep all this shit straight without having an aneurysm?
Vaarsuvius: ...which in turn means that he knew that you would know that he was in the empire, and that you would know that he would know that you knew. Elan: Which means... that I'm totally confused.
Defied by Roy when the team is discussing the extent of Girard Draketooth's duplicity, including the possibility of a double-bluff.
Durkon: Aye, but wha if Girard thought o' everythin' ye just said, an' did tha opposite, just ta trick us?
Roy: I think we're quickly approaching the point that it doesn't matter if he did.
Homestuck: The duel between Terezi and Vriska in Act 5. Terezi proposes that they flip a coin to decide whether Vriska stays or goes. Both parties realize that Terezi is employing Double Speak, so "go" really means "die". Both parties know that Vriska can alter probability and make the coin fall on whichever side she wants. Terezi expects Vriska to call her bluff, by making the coin land on "go" and then turning to leave. Vriska does precisely that, expecting that Terezi won't have the stomach to stab her in the back. This is even lampshaded by Doc Scratch, who narrates their fight.
Doc Scratch: Naturally, the Thief [Vriska] knew this was her intent all along. ... And the Seer [Terezi] knew the Thief knew all this as well. Just another pair of cheaters attempting to play with their cards face up. Amateurs. Each was gambling, not with any vehicle of probability, which had been eliminated from the equation, but with each other's intentions.
In the end, Terezi's Seer of Mind power shows her exactly how bad not stabbing Vriska would be, and she goes through with it.
Lottie: Can't let him know that I know. What if he guesses? Then I can't let him know that I know that he knows.
El Goonish Shive:Grace tells Ellen that she told Raven that she knows about him being an elf but doesn't tell him the that other people know about his nature as well. She also believes that he doesn't know about Ellen knowing about his knowledge that Ellen is a magical being.
Used without being named in one of Ayla's Whateley Universe stories, "Ayla and the Network". The ENTIRE plot is various groups having a Gambit Roulette. The winner is the one who can end the "I know you know" game. It's Thuban and Ayla. Ayla, who knows people would break through any security she has, so BOTH her laptops are traps, and Thuban, who set up the ENTIRE blackmail plot!
Experienced players in Mitadake High pull this kind of thing all the time when debating whether or not to give out their PDA Numbers. Unless the host has disabled the computers due to abuse, in which case there's no risk whatsoever.
At the start of most games, the Mafia/werewolves/evil team all know who is on the evil team, while the good team knows nothing but the game's rules (and may not 100% know even that). Exploiting this fact is the primary tool the good team has to root out the baddies, particularly if the cop is keeping quiet or dead. The evil team knows this, and will avoid letting on too much... which they might well overdo by conspicuously not talking about each other, or affecting more suspicion than is reasonable.
The Skeptics Guide to the Universe podcast has a regular feature called "Science or Fiction?" in which the host gets his fellow casters to try and determine which of three science news items is fake (two are true). Occasionally he'll throw in one that's so ridiculous that it has to be fake, but the panelists are reluctant to pick it, naming this trope as a reason why.
In the Rocket Jump video "Mexican Standoff", the characters get so many levels into this that they have to stop what they're doing and draw it all out on the ground with chalk in order to figure out who is on what side and why.
Freddie: Did you just get here, son? I knew you knew I knew all along all along all along.
Kronk does this in one episode of The Emperor's New School. He is faced with a choice of two levers and is instructed to pull the one he wouldn't pick, due to his ineptitude with levers. He does an I Know You Know I Know for a while until Kuzco interrupts by saying "Yeah, this went on for another two hours," and fast-forwards through the whole thing.
Done in Foster's Home for Imaginary Friends, where Bloo is setting up a humiliating surprise party for Mac, and all his efforts play right into Bloo's hands, even when he thinks he's doing the opposite of what Bloo thought he'd do.
Taken to extremes in the Danger Mouse episode "The Statue of Liberty Caper", where Danger Mouse and Baron Greenback both try to outwit each other with regards to the location of a trapdoor in the floor, leading Danger Mouse to say "I guessed that you'd guess I guessed you guessed I'd guessed you'd guessed and out-guessed your guess, I guess".
Ends up as something of a Xanatos Gambit / Crazy-Prepared in that by the time the scene has finished Dangermouse has saved Penfold's Auntie, Penfold (twice) and the famous buildings of the Americas due to utilising the extreme number of guesses to blow up Greenback's shipboard computer - by getting Greenback to ask it to figure out exactly who had outguessed who.
Kim Possible: Kim and Ron notice that Shego left a far too obvious clue that she had stolen the McGuffin, so clearly she and Drakken were setting up a trap. Unless they wanted them to think it was a trap and avoid it, in which case the way to confound them was to walk right into it, except it was a "trap-trap": Drakken knew that they knew that Drakken knew that they knew that it was a trap.
Played straight (as straight as anything on that show, anyway) on Cartoon Planet during the following conversation about network executives:
Zorak: Maybe that's just what they want us to think! Space Ghost: Hey, you know what? I think that's just what they want us to think! Zorak: I think, that they think, that we think, that that's just what they want us to think! Space Ghost: Brak, what do you think? Brak: I just, I don't even have the slightest idea what you're talking about.
Played awesomely on an episode of Chowder where the title character is trying to stop his Hyde-like Sleep-Eating form from finding the stash of food he hid, thinking about three steps ahead of himself, sadly to no avail.
In The Penguins of Madagascar, things get out of hand when Skipper tries to get back real fish instead of the tasteless fish cakes the penguins have been forced to eat. Julien tried to sabotage the operation.
Julien: So you see, we have the crates with the real fish, while yours are filled with only the phony fish cake. So hahaha-ing. Skipper: Oh, nice try, Ringtail. But I know how much you hate the smell of fish. I was expecting a move like that, which is why I switched the crates before you even got back to the zoo. Julien: Ah, but I was expecting you to be expecting that, so we switcheroo-ed the crates on the pier before the fish got loading on to the truck. Haha! Skipper: Doesn't really matter, because I just switched these crates during your last flashback. Julien: Well I switched them while you were saying you switched them. Skipper: And I switched them last the time you blinked. Julien: Yes, but I pretended to switch them so you actually switched them back. Skipper: Oh, but I double switched. Julien: And I triple switched. Skipper: I million zillion switched. Julien: And I switched them to infinity! So you have to shut up a little bit. Skipper: Ah, but what you didn?t see coming is that [pulls off costume] I am actually you! Julien: Okay, nicely played. But if you are me, then by processing of elimination, [also pulls off costume] I must be you! Skipper: Maybe, maybe. But if you are me, and I am you, then we must both be?
An episode of Samurai Jack had Jack and Aku agreeing to a final duel with no swords or special powers. Naturally, Aku cheats, as Jack knew he would and so prepared for by bringing his sword and hiding it. But Aku knew Jack would know that he cheated, and had a minion find the sword. But Jack knew that Aku knew that Jack knew that Aku would cheat, so he planted a decoy sword. But Aku knew that Jack knew that Aku knew that Jack knew that Aku would cheat, so he had his minions look for more swords. But Jack knew that Aku knew that Jack knew that Aku knew that Jack knew that Aku would cheat, so he had his sword buried underground.
In the Code Lyoko episode "Contact", Odd and Yumi have an instance of this.
Yumi: Are you thinking what I think you're thinking?
Odd: Yeah! Good thinking. *he smiles*
Used in the Young Justice show. The team is using a former Justice League hideout that was compromised. As explained by Robin; "They know we know they know."
The Flintstones has one of these. It's something to the effect of "Even though he knows she knows he knows he knows she knows he *doesn't* know..."
A semi-real life example, meaning it's actually an urban myth, is Winston Churchill's Coventry dilemma. Allegedly, Churchill had to allow the city of Coventry to be bombed, to prevent the Nazis from finding out about the British spies in Germany who knew about the bombing plan. In reality, the British tried to jam the Germans' radio guidance system, but had to take a guess at the frequency to use. They got it wrong.
When Alexander Litvenenko died, some of the speculation on who killed him got to this level. Welcome to the Cold War.
CIA chief of counter-intelligence James Jesus Angleton spent the 60s and 70s turning the CIA upside down looking for a KGB mole. Some agents began to suspect that Angelton was a mole, on the grounds that starting a witch-hunt for a KGB mole is exactly the sort of thing a KGB mole would do.
In the fictionalized version in Martin Gross' "The Red President", the White House allows the Angleton figure ("John 'the Baptist' Davidson") to be framed and disgraced so the Soviets won't know that THEY know who the real mole is.
There is a formal system called modal logic that can be used to model what certain agents in a system know (including what they know/do not know about what the other agents know/do not know).
There is an active research field known as adversarial reasoning: essentially, building models that allow you to predict the actions of an adversary. Once the adversary happens to get a hold of your model it becomes rather useless, as he can make sure he does something other than what is predicted. So you simply create a new model - one that takes into account the fact that your adversary has the old model that he thinks tells him what you think he is going to do! The eventual end state is left as an exercise for the reader.
One classic example from the Second World War: an agent was sent to Great Britain by the Germans, who intended that the British intelligence service capture him and use him as a double agent, at which point he could tell the Germans how British counterintelligence functioned. He proceeded to explain this plan to the Brits, who then had him send back two different sets of reports to Germany. One contained what the Brits wanted the Germans to know; the other contained what the Brits wanted the Germans to think the Brits wanted them to know.
Very common in counter-espionage, classic example is Radio Game. Allies sent a spy, Germans knew that he was a a spy and turned him, Allies knew that the Germans knew, Germans knew that the Allies knew that they knew and finally ended the charade.
Studies of animal intelligence sometimes use this trope as an analogy to model a species' cleverness in social interaction. Humans are the only species known to be able to do five levels of I/you know/think, while other great apes seem able to manage four (e.g. they can bluff and be subtle about it so the other ape won't catch wise). Or maybe the apes are far better at it than humans.
The Blue-Eyed Islanders puzzle relies on this to an insane level, in that it ultimately depends on a 100-story tall tower of hypotheticals. Let's say that K(0) is the knowledge that there exists someone on the island with blue eyes; and K(N+1) is the knowledge that everyone knows that K(N). So if I know K(1) it means I know everyone knows there's someone with blue eyes on the island; if I know K(2) it means I know everyone knows everyone knows there's someone with blue eyes on the island; and so on. The crux of the riddle rests on how, from being given K(100), everyone on the island deduces they have blue eyes by a mind-numbing 100-day process of collapsing hypotheticals.
Have you ever tried seeing the color of your own eyes in someone else's?
Professor Ian Stewart in Math Hysteria calls these Common Knowledge puzzles (his own version is about an order of logical monks who would be embarassed if they realised they had a blue blob on their forehead, and are too polite to point out that another monk does). He cites an article by David Gale in the Mathematical Intelligencer as providing an overview of the puzzles, including the ultimate version: a Mad Mathematicians' tea party in which it is used to deduce what random numbers the mathematicians have on their hats.
In Game Theory, the concept of Nash Equilibrium is a means to overcome this kind of stalemate.
The Two Generals' Problem plays with this. Two generals have their armies surrounding a target. Each can send a message to the other saying they're ready to attack, but the other might not get it. They can't just send a message and go, because the other general might not get it and won't know. They can't just wait for the other to respond, because then the second message could be lost, and they won't know the other knows. The end result is that, no matter how many messages are sent, they won't be any more sure than if they just sent one message and hoped it arrive. While this situation is impossible to solve in theory, there's a lot of ground gained there by taking the engineering approach and looking for a solution that will work well in practice.
The problem is enhanced by the possibility that the defenders may be intercepting and corrupting messages. If it's merely a question of messages getting through, sensible organisation should only require a couple of confirmations before further messages become irrelevant.
More specifically, the practical solution is to evaluate the probability of success of a single message transmission, and to then repeat the transmission until the probability of failure has been reduced to a calibrated trivial percentage (say the message has a 1/10 chance of failing, then after sending it once you can be 90% sure that both generals have heard the message, after the first response it's up to 99%, then you might want to send a third one to bring it up to 99.9%, then stop if you can live with a one in a thousand chance of failure, or keep going if you can't).
The best solution is for the second general to fire a flare above the city to signify having received the first message.
How about agreeing on a series of colored flares: the first general sends up a flare (say, red) meaning that he's ready to attack, and the second responds with the same color to indicate that he will attack as well. Stealth is an issue, but...