"How about I observe. Therefore the universe is. Therefore, we can say if the human beings who observe the universe hadn't actually evolved as far as they did, then there wouldn't be any observations and the universe wouldn't have anyone to acknowledge its existence. So it wouldn't really matter if the universe existed or not. The universe is because human beings know it is."
—Itsuki Koizumi, The Melancholy of Haruhi Suzumiya
For any given story, there exist basic elements that are required for the story itself to happen; there would be no story otherwise.
The original Anthropic Principle is a theoretical explanation of why the conditions of the universe are so perfect for the existence of intelligent life (like us humans on Earth). Why? Because without those conditions, we wouldn't even be here to be making those observations in the first place. Even though the raw probability of those conditions is astronomically unlikely, our very existence requires us to accept that it must have happened somewhere.
The Anthropic Principle as it applies to fiction is similar: Every fictional universe has fundamental, axiomatic elements without which its story simply could not exist, and the reader must accept those elements in order to enjoy the work. The ultimate expression of this trope is Minovsky Physics -these elements are actually carefully planned in advance, ensuring a logical transition from real life to the fictional universe.
For example, Slumdog Millionaire requires a lead character able to get on a TV quiz show and do surprisingly well, to the point that the show itself becomes Serious Business. For House to happen, Dr. Gregory House must be able to keep his job as a genius diagnostician despite being a major Jerkass. For Snakes on a Plane to happen, there must be snakes on a plane. For a Gundam series to happen, giant Mecha must be possible. And to the eternal enmity of all physicists, you cannot have a Space Opera without Faster-Than-Light Travel ... and the resultant Cool Starships must have people on them (even if it's just because suitable machines can't be trusted) because it's hard to tell entertaining stories about unmanned probes. For an Adventure Game or RPG to happen, there must be someone who the player can guide through the Sorting Algorithm of Villain Threat and eventually beat up the Big Bad in single combat. And in all of the above cases, if Adventures of those types can be had regularly, it is an Adventure-Friendly World.
This is in some ways the opposite of the MST3K Mantra, which says that some details don't need to make sense because they ultimately don't matter; the Anthropic Principle says that certain details of the story do matter because they are the foundations that the story itself is built upon, and accepting those details on faith is critical to the audience's enjoyment of the show, even if it doesn't make much sense from an outside viewpoint.
- This trope is surprisingly often defied by critics reviewing Comic Book film adaptations and Fantasy, when they dismiss an entire genre in its opening paragraph by pointing out that the very premise of the story is realistically impossible and rests upon childlike simplifications—and anyone who takes such stories seriously must by definition be irresponsible and childish themselves; see Complaining About Shows You Don't Like.
- Conversely, the need for the plot to work as an actual story is a problem for overzealous fans who attempt to explain away an aspect of the story that requires Broad Strokes. They may foreswear any literary, character-driven, or other interpretations, placing rigorous consistency above whether or not it makes a good story; and apply similar standards when judging film adaptations, even when there'd be no film if their proposed changes were made.
- Sometimes the author is dissatisfied and rebels against the underlying premise. Changes to the basic premise to make it "consistent" or "relevant" (due to Cerebus Syndrome or Executive Meddling) will require a Continuity Reboot or a total Retool of the premise. Compare They Wasted a Perfectly Good Plot.
Many Real Life theories about the Anthropic Principle rely on notions of The Multiverse and probable alternate universes (which do not need to actually exist to be considered alternate universes, since it makes little practical difference to our universe and us in it.) Such theories excite the Daydream Believer. Not to be confused with Transfictionality, where the author creates his own Alternate Universe by imagining the story.
This scenario is actually the one currently favoured by a lot of physicists, since String Theory (apparently) requires the existence of something like 10500 different sets of physical laws. A similar argument explains why we find ourselves born onto the relatively congenial surface of a planet, rather than inside a star or deep space. (Looked at that way, it starts to seem less like rocket science and more like "and?")
In a sense, it can often be assumed that the events portrayed, however unlikely, are still occurring within the realm of conceivable probability. For example, if a plot initiates because a character experiences an incredible event; even if the probability of said event was relatively unlikely, it can be assumed that the character also experiences many completely mundane events where nothing extraordinary happens, and that this event was simply the reason that the episode has been shown to viewers. In short, the events portrayed are not chosen at random from an arbitrary sampling of all existing events (nor even the characters, locations, etc), they are simply the events which are deemed to be of interest. Unlikely events do happen in real life, just not all the time. Improbable does not mean Impossible. If someone were to select only the most interesting events that happened to the most interesting people, and write only about them, then even regular human life may seem extraordinary to the reader. It does not make those events any less believable.
In this way, it could even be reasoned that Truly Fantastical stories are conceivable within the defined universe. For example, Superheroes may seem to be continuously rescuing those in distress and foiling evil schemes, however these may very well not be everyday occurrences; they may even conceivably happen weeks apart, with simply nothing of interest occurring between, and thus those events are the only ones the readers are told about.
There's actually a whole genre of comedy based on this sort of thing, films like Big Trouble and National Lampoon's Christmas Vacation and books like A Confederacy of Dunces. A lot of the fun comes from seeing just how much worse things can possibly get for the main characters, as a bunch of independent actors, all of whom have only slight knowledge of each others' actions if any, do exactly the wrong thing to screw up everyone else's day.
- When you think about it, Death Note hinges on a whole gigantic mountain of coincidences that could be easily handwaved by themselves, but in aggregate are pretty incredible, particularly as the story goes on. Okay, so this incredible artifact of doom falls into the hands of an amoral supergenius; wouldn't be much of a story without that, would there? Alright, then the other super-smartest ultra-genius in the entire world gets involved. Well, that's sort of his job; the actions of the first genius attracted the second one. But Misa getting her own Death Note, living in the same country as Light and falling into an obsessive love with him? What are the odds? Doesn't matter. She is how she is, and that's why the story played out the way it did. It wouldn't have been near as interesting otherwise. It only spools out further from there.
- Kyo Ani evidently likes this trope; Kagami and Konata discuss it in Lucky Star.
- The anime Suzumiya Haruhi. Koizumi explains this principle to Kyon, when describing why some members of his organization think Suzumiya Haruhi is a god. His explanation can be summarized as: "The act of writing means the pen has ink in it. There are pens without ink, but no-one is using them to write. People throw them away or put ink in them." Likewise, there are universes without intelligent life, but as no-one is there to describe, influence, or travel from them, they effectively do not exist... until someone visits them. : He later discusses the very trope that is the subject of the article when talking about fiction, saying that fictional detectives always "accidentally" end up at crime scenes because otherwise there would be no story.
- The 2008 remake of Day of the Dead illustrates an example common to many zombie films. It is explained that the zombie virus can be transmitted by air in addition to being bitten by a zombie. When one character asks why all the main characters are uninfected, the scientist explains that "some people are just immune to the airborne aspect." Although it may seem like an incredible and unexpected coincidence, they would necessarily have to be immune to be main characters.
- Given a Shout-Out in one BattleTech novel, where it's revealed that Vladimir Ward firmly believes in a personal version of this—that is, he's earnestly convinced that the Star League fell and the Clans came into being just so that he could be born at just the right time for the invasion and go on to conquer the Inner Sphere. To him, that's actually the simplest and most logical explanation for everything in his life up to that point.
- The Discworld series have this as a major theme in general: Discworld is a world of stories. The world often conspires to get the people in the stories to play their roles, no matter what the consequences. The people often aren't happy with this.
- One book mentions the Unseen University Professor of Anthropics, who has created the Extreme Anthropic Principle: the theory that the universe is here solely for the Unseen University Professor of Anthropics. It is further mentioned that everyone, with a few changes of the Insert Name Here variety, secretly believes the same thing.
- A common joke in China is wondering why Sun Wukung from Journey to the West (a demi-god who can jump over continents in one bound and carry half a mountain on his back) can't just carry Xuanzang straight to India.
- Next's Cris Johnson literally lives by means of this trope; he can see up to two minutes into the future at any given time, and in certain situations even further. It's as natural to him as seeing lightning before hearing thunder is to most people, and he can actually dodge an entire clip of machinegun bullets in this manner, visualizing his alternates dropping dead in his wake.
- Assassin's Creed uses this to Hand Wave a traditional video game trope. The plot of the game involves a man reliving the memories of an assassin ancestor using a special machine that reads genetic memories; what would be a Life Meter in most games is called a Synchronization Meter, explaining how in synch he is with the historical events. Performing actions that are badly out of character (like killing innocents) or just plain inaccurate (like dying) lower the Synch Meter. Incidentally, it was made by the same team as the Prince of Persia series, mentioned below. Logically, this implies that Altair was an incredible Badass, since being hurt at all lowers synchronization- thus he never got hurt...
- In turn, we also know that Altair and Ezio must at some point have children, since they eventually become Desmond's ancestors. So when we meet Sofia in Assassin's Creed Revelations, It is even more obvious than usual that she is the Love interest.
- The game BioShock. Near the end of the game, it is revealed that every action the hero has taken was the result of post-hypnotic suggestion compelling him to act. If you attempt to defy the mind control earlier in the game, not only do you not progress, but you never even get to the point where you can discover the true reasons behind your actions. Of course, if this happens, the plot stalls. There is only an interesting game in the first place because the plot proceeded the way it was meant to - you are playing it only because it happened that way.
- In the Chzo Mythos, as the game "Trilby's Notes" is a recollection of the main character, it only makes sense that he must survive to write them. Should he die at any time during the game, the game mentions how the notes "mysteriously end" at that point, and perhaps were not actually written by the protagonist.
- Cry of Fear: The whole story, and all the events that occured, turn out to have been written by Simon as a form of theraphy after the car crash from the opening cutscene. If he had not been struck by that one car, the story had not been written. This is demonstrated effectively in the alternate gamemodes Co-op and Doctor mode; the playable police officers get sucked into the book, and the only way for them to get out alive is to go from the end to the beginning and prevent the accident from ever happening. Dr Purnell however, enters simons mind willingly to destroy the book.
- A variation happens in Freddy Pharkas: Frontier Pharmacist. The story is told by a local old coot, and would on a proper playthrough be about how Freddy saved the town. If you die, however, the Have a Nice Death message is the coot ending the tale of how Freddy died. "And that's how Freddy Pharkas drowned in the swamp."
- In Metal Gear Solid 3, the death of Naked Snake or Ocelot both result in the infamous "time paradox" game over screen. The future course of the story depends HEAVILY on these two characters, so it just wouldn't do for them to die in the prequel.
- In Snatcher, while the Continue function works as standard, the Chief will shout at Gillian after the factory opening if he dies during the attack of the Insectors. "Do you hear me, Seed? No more Game Overs!" In Policenauts, Jonathan will complain if you get too many Game Overs, and then suggest hints (and if you carry on failing, simply say "I'm going to get him this time.") In the original Metal Gear Solid, Mantis comments on how many traps Snake has fallen into - the traps are instant-death pits, suggesting Mantis is able to see Snake's Game Overs. Hideo Kojima likes this trope a lot.
- Persona 4 goes to an unusual amount of effort to justify its anthropic principle. The moment you discover the TV world, it's obvious you'll be going there and fighting monsters, but the characters react realistically to this discovery rather than rushing in, with the result that gameplay doesn't fully open up until about three hours in.
- The game Prince of Persia: Sands of Time, lampshades this. Whenever the Prince dies, we hear him tell us,"No, no, that wasn't how it happened. Hold on." Because to have the Prince die would mean that the story of the game that is interesting would not be told, that he would not be there at this very moment to tell the story of his adventure to begin with.
- A similar situation occurs in Monkey Island 2 Le Chucks Revenge: there's no way to die in the game, except one time where you are disintegrated in acid. The person you are telling the story to immediately calls you on this, as you can't have been disintegrated if you're there telling the story, looking very integrated indeed.
- The game Sacrifice features the same conceit, with almost the same line: "Of course, that's not what really happened." The protagonist is explaining the story to one of the acquaintances he met during it.
- In Space Quest V, Roger Wilco must keep his love-interest, Beatrice Wankmeister, alive, or else get a game over. Why? Because the fact that she and Roger eventually have a son is part of the premise of the time-travel laden Space Quest IV, as the son saves Roger in the opener of that game. If Beatrice does not survive, Roger Jr. will not be born, cannot travel back in time to save his dad, and thus Space Quest V can not happen!
- Part of the Interactive Fiction game Spider and Web has a similar approach: you're interrogated in a flashback, but with an audience, and if you do something unbelievable in the flashback, he'll stop you and insist you tell the truth. This is eventually subverted as the main puzzle of the game is to give a a plausible explanation for starting conditions of the game, while at the same time hiding what you did prior to capture that will allow you to escape.
- Though it is never mentioned explicitly, the anthropic principle is the entire premise of The Hero with a Thousand Chances.
- Of course, intelligent lifeforms born in a star or in deep space would find those environments relatively congenial, and consider the surface of a planet to be unpleasant.