What’s a story?
“Story” is a very broad category, even when counting only fiction. It includes:
– nonsense stories that are supposed to be stupid and make no sense:
One fine day in the middle of the night,Two dead boys got up to fight.
Back to back they faced each other,
Drew their swords and shot each other.
A deaf policeman heard the noise,
Came and killed the two dead boys.
– meta-fiction (stories about stories), like Borges’ stories that are literary analyses of imaginary stories (“Pierre Menard, author of the Quixote” is my favorite)
– ancient Greek rape comedies [h]
– Goodnight, Moon
– Nietzsche’s Thus Spake Zarathustra
– Waiting for Godot, a story about nothing happening
– this story from the infancy gospel of Thomas:
After that again he went through the village, and a child ran and dashed against his shoulder. And Jesus was provoked and said unto him: Thou shalt not finish thy course. And immediately the child fell down and died. … And the parents of him that was dead came unto Joseph, and blamed him, saying: Thou that hast such a child canst not dwell with us in the village: or do thou teach him to bless and not to curse: for he slayeth our children. And Joseph called the young child apart and admonished him, saying: Wherefore doest thou such things, that these suffer and hate us and persecute us? But Jesus said: I know that these thy words are not thine: nevertheless for thy sake I will hold my peace: but they shall bear their punishment. And straightway they that accused him were smitten with blindness.
I don’t believe there are rules about what kinds of fictional narratives can be set down as text and appreciated. Anything goes. So what am I talking about when I talk about rules of fiction?
A general evolutionary theory of fiction
I think people have evolved cognitive dog-treat-recognizers, things in their brains that give them little jolts of pleasure for doing things that tend to get their genes propagated. When we read fiction, we get these doggy treats even for things we didn’t do ourselves. 
The evolutionary explanation for erotica is obvious: People enjoy sex. (I don’t know why there isn’t food porn, too.) Bashing your opponent on the head gives you a different kind of jolt of pleasure. Action stories are efficient structures that give you jolts of pleasure at bashing other people on the head without suffering the (culturally-specific) jolts of guilt that prevent people from bashing each other on the head all the time.
“Dramatic” stories play on the reader’s emotional bonds to the characters. This requires a complicated story structure to build up these bonds, then yank on them so you react as if these things were happening to your friends.
Dramatic stories are like roller-coasters. Roller coaster design has rules. Some are engineering: The track has to go up before it can go down. Some have to do with what patterns of tension and release feel dramatic: You need to cluster small, fast curves and loops together; you need to have moments of respite between these clusters.
None of the examples I listed at the start of this post are dramatic, except for the rape comedies. So drama isn’t found in all fiction. But it’s in a hell of a lot of fiction. Drama is the backbone behind most good stories. It’s what you feel when something is at stake and you care what happens. When people say stories must have conflict, or that there must be two false climaxes followed by a climax and resolution, or that a play or movie must have a three-act structure, they’re talking about dramatic stories. If you read Syd Field, Jack Bickham, or Writer’s Digest, you’re going to get theories of dramatic structure. Most of what is written about how to write novels and movie scripts, is written as if conflict-based dramatic stories were the only kind of story. So they’re a pretty important class of stories! 
BUT. There are dozens, maybe hundreds, of sets of “rules” about dramatic stories, or “basic plots” of dramatic stories. They’re… helpful, maybe. But most of them just address the plot: What sequence of events happen in a story? They’re stuff like this:
1. Once upon a time there was …
2. Every day …
3. One day …
4. Because of that …
5. Because of that …
6. Until finally …
What’s the point of that? You’d have to really work at it to write a story that didn’t fit that structure. I want to understand what my brain is looking for when deciding whether to give me a mental doggy treat. Knowing a hundred slightly different plot sequences that trigger it is a good start, but we can do better.
“Literature” is, I’m gonna say for the moment, stories that make you think about things outside of the story. In my mind, Song of Ice and Fire is fantasy, while Lord of the Rings is fantasy and literature. Twelfth Night is (bad) romance. Romeo and Juliet is (bad) romance, and literature. 2001 is science fiction. Brave New World is science fiction and literature. If you read Aristotle or Dramatica theory, you’re going to be reading about how stories make you think.
Literary stories, I think, reward you for learning. They’re simulations that teach you what might happen if you do one thing in some set of circumstances. The dog-treat mechanism in your head drives you to seek literary lessons that tackle the questions currently important to you. This may account for the strange fact that there are specific story types that many people love and many other people think are stupid.
So stories don’t serve any single function. There are as many broad, top-level story types as there are evolved patterns of experience that trigger mental doggy treats, and a good story will trigger lots of them. But a few top-level story types are very general and very important, and I want to understand them better. If our more-specific theories about how stories work mate well with the top-level evolutionary justification, it’s a sign that we may be onto something.
A general evolutionary theory of popular bad fiction
The brain doesn’t expect your experiences to be fictional. So it gives you a reward even when you’re just imagining someone else having these experiences. An ape gets a big jolt of relief or exhilaration for outwitting a predator or enemy, and that’s fine, because that doesn’t happen much in the wild. But your brain wasn’t informed that you can sit down at B. Dalton’s and read trashy novels and make it give you that jolt every ten minutes, for things that don’t benefit your genes at all.
Some “popular but bad” story types might be ones that fool your brain into thinking it’s succeeding or learning when it isn’t. Nonsense stories, for example, are bad baby literature. Babies learn fastest by looking at things they haven’t seen before. They get cognitive dog treats for looking at anything surprising, even if it’s surprising just because it’s really stupid. Nonsense stories don’t help anybody learn anything, but because they’re full of things that don’t make sense, they keep triggering your brain’s reward for paying attention to things that you don’t understand yet.
Even stories that benefit you some way can be “junk stories” if you indulge in them too much. In a world where we can seek out exactly the kind of food we want, we end up eating too much fat, salt, and sugar. In a world where we can seek out exactly the kind of story experience we want, we end up reading “too much” (from the perspective of our genes) of certain kinds of stories.
So I expect successful stories to include “good good stories” that reward you for confronting things in fiction that help you or your genes in real life, “junk food stories” that we over-indulge in because they give us big rewards for things that don’t happen very often in real life, and “good bad stories” that reward you for mentally jacking off [α].
TO BE CONTINUED…
h. A Greek rape comedy is a once-popular story type in which a young man prepares to marry a young women who, unknown to him, was recently raped. When he realizes she’s pregnant, he must cast her off as a shamed woman. But then it turns out that he was the man who raped her, so it’s okay. Everybody has a good laugh and they get married and live happily ever after. (This summary is a little unfair to the Greeks, since they didn’t have a concept of, or at least a word for, rape. On the other hand, that in itself is another indictment of them.)
1. Transhumans will of course evolve brains smart enough to distinguish real experiences from fictional ones, and to reward them only for real ones. They will therefore no longer enjoy fiction.
2. It’s hard (maybe impossible) to distinguish between drama and tension. Dramatic structure, whether it’s 3-act theory or scene and sequel structure, can be used to create drama, but it can also be used in action movies where we arguably don’t care much about the characters, like Crank.
α. Not that jacking off is bad. Or using birth control. You don’t always gotta do what your genes want you to. Usually, your genes are looking out for you. But plenty of stories are designed to teach you altruistic lessons that are good for your genes, or your society, to your detriment!