Back in high school, I had a marvelous history teacher who made a point of going into more than memorizing dates and names and places. One of the key things I took away from that class was the concept of necessary and sufficient causes, and the difference between them.

Necessary causes are the things that absolutely must happen in order for some event or change to occur. In terms of plot, if you want to write a classic murder mystery, there has to be a murder. Sure, there are all sorts of other crimes, from theft to blackmail, that you could write about instead, but they won’t be murder mysteries. Without the murder, there won’t be a story.

But necessary causes are not always sufficient all by themselves. In order to have that murder mystery, you need the murder, but just the murder isn’t enough. If the murder is never discovered, or if the murderer kills both the victim and himself at the scene of the crime, there’s no mystery. (Which is why most people who pick up a murder mystery that opens with a murder-suicide will immediately assume that the real murderer has faked the evidence – because if this really is a murder-suicide, the story isn’t going to be a murder mystery.) The story needs something else. Most of the time, the mystery is “who did it?”, but sometimes, everybody knows who did it and the mystery part is in figuring out how they did it (and proving it enough to arrest the murderer).

Necessary causes are specific and immutable: without X, you don’t get Y, not ever. Sufficient causes can be many and varied; they come in an assortment of different numbers and combinations. One or two big events can work, but so can a lot of little things that add up. The only requirement is that there are enough of them to tip the balance so that Y actually happens.

Plots and stories are about the sufficient causes – all the different ways of getting from here to there. And that can be a problem. A lot of people are quite good at figuring out what the absolutely necessary things are, and making sure to include them. Often, though, they’re not so good at going beyond that. They put in the necessary elements, and they may even realize that they need a bit more than that…but they don’t look closely at just what it’s going to take to be enough to tip the story in the direction they want it to go.

The whole thing is made more complicated by the fact that exactly how much is enough to justify a plot twist or story event can vary wildly from reader to reader. Some people take a lot more convincing than others. Furthermore, there can be more than one thing in a story that needs sufficient cause before the whole story is believable. I had a horrible argument once with a gentleman who didn’t understand why his beta-readers didn’t believe his fantasy adventure. His central plot developed quite logically, after all … but a lot of the background politics were, at best, thin; at worst, they looked much too convenient. There weren’t sufficient reasons behind them to make the readers believe them, and therefore they undercut the believability of the main plot. The background didn’t matter to him, so he thought he had plenty enough to make the story work; unfortunately, his beta-readers had different standards for what was enough, and he hadn’t met them.

In other words, it’s necessary for the main plotline to hang together, but often it’s not really sufficient. Even if you leave aside things like interesting, well-rounded characters and a writing style that doesn’t go thud-clunk, which are also necessary for many readers, a novel has subplots and background and an assortment of other details that have to make sense. An author who wants to write a stripped-down, minimalist sort of story is mainly going to pay attention to the necessities and only the necessities – but in order for that to be enough to satisfy, that author is going to have to pay extra attention to what is necessary at all the different levels of the story, because there aren’t going to be very many places to work them all in.

An author who is doing a more usual sort of story still has to get all the necessary stuff in – it wouldn’t be called necessary if they could leave it out – but there are more possible places to put those important bits. It is even possible, sometimes, to let them be implied instead of stating them (though that can get tricky, because no matter how clear you try to be, some people will miss picking up on it).

15 Comments
  1. I love your writing tips in general. If I ever wanted to write a fiction or fantasy novel I would read your blog from start to finish to understand everything I should keep in mind for it. But, let’s say I wanted to write a non fiction book. Which of your basic writing blogs would apply to non fiction? Have you ever written a non fiction?

    • Jessica – Good question! I think I’ll have to do some posts on that. Meanwhile…well, pretty much everything could be applied to nonfiction, a least in part, depending on the sort of nonfiction you wanted to write. For instance, characterization stuff and plot would apply to some extent if you were writing a biography, but probably not if you were writing a book on how to fix a car. Things like description, structure, process, managing your time, etc. apply to everything, though some of the techniques you’d use for fiction wouldn’t transfer. Viewpoint – for nonfiction, that’s usually a variety of omniscient, which I haven’t posted about much yet; OTOH, if you were doing memoir, some of the stuff on first-person viewpoint might be helpful.

      Mary Ann – Go for it!

  2. My mind went down a rabbit trail following a murder mystery beginning with a murder-suicide. That could be the precipitating event, the sufficient cause, for the murder(s)-to-be-solved. I’ve never tried writing a mystery, but that would be a fun red herring.

  3. I’m not sure whether our mental models overlap completely, but your post has helped me to recognise that what I’m doing right now is not ‘writing the boring bits to get them out of the way so I can go back to the plot’ but ‘making sure that everything is in place for the main plot to move on in a natural, non-coincidental manner.’

    Or as I said on my blog:

    Mortar might be cheap and boring, but if you try to build a house solely from bricks, you’ll soon recognise the limitations.

    (Remember how much I’ve struggled with metaphors? I think I’ve cracked that one.)

  4. The funny thing about this post is that in ecology class today, we were talking about resources=anything necessary for survival, so that’s where my mind went. 🙂

    I remember when I read Lloyd Alexander’s Westmark trilogy, which I assumed (based on his other works) would be fantasy. I kept looking for some sort of magical creature, object, spell, SOMETHING, to prove it was fantasy, and never found it. The books are actually more of adventure-in-invented-country for that reason.

    • green knight – Whatever triggers a useful realization is, well, useful. And yeah – it’s possible to build a house using drystone techniques, but that’s pretty advanced construction for most folks. And if you try to build drystone when you really need the mortar, the house will fall down.

      Chicory – For the Westmark books, I think the imaginary history IS the fantasy part, but it doesn’t seem to be a terribly popular genre. I think that’s because those sorts of books are usually classed as fantasy, so the mainstream readers don’t find them, and the fantasy readers want spells or dragons or magic rings, so they don’t care for them.

  5. I think you’ve just described my current form of outlining. I do a necessary outline and let my subconscious do the sufficient stuff as I write the first draft. Nice to have that clear – thanks!

  6. “For the Westmark books, I think the imaginary history IS the fantasy part, but it doesn’t seem to be a terribly popular genre. I think that’s because those sorts of books are usually classed as fantasy, so the mainstream readers don’t find them, and the fantasy readers want spells or dragons or magic rings, so they don’t care for them.”

    I like imaginary history, both as a writer and as a reader. I’ve got no particular hang up on magic, and it never bothered me that Westmark didn’t have any — I used to read just as much historical fiction as fantasy anyway. So I keep having stories set in imaginary places, but without any magic in them, pop into my head. They don’t really fit into any of my fantasy worlds, and I eventually ended up saying, “Okay, whatever, I guess I have an Imaginary History World that I’m writing in as well — let’s give it a name and add it to my database.”

    Unfortunately I have exactly the problem described above when trying to figure out how to do anything with those stories. They just don’t *fit* into an established genre. If you call them historicals the historical readers whine about the fact that they aren’t based on real history, if you call them fantasy, people whine about the lack of magic, if you call them science fiction people whine about the lack of advanced technology. :Sigh:

    The most recent story I dreamed up is yet another of these. Seems to be a roughly WWI era romance/political-intrigue/adventure story. I guess I maybe shouldn’t be in any hurry to add it to the queue, but it seems a pity. I think it’s just as good a story as any of my others, and the setting is way different from anything else I’m working with, so it would provide some fun variety for me.

  7. @Michelle

    In computer animation there is a problem we call “The Uncanny Valley”. That is when you draw a face that is TOO close to realistic and it became ‘alien’ and creeps out your audience. (You can get the same issue with scenery and animals, but most often with human figures) The solution is to back off the realism slightly and stylize it more.

    Looks like you can get the same issue with books, if your made up world is ‘too close’ to realism then the differences will annoy/anger your readers. Try decorating your world with some SciFi or Fantasy elements. Nothing that changes your main idea, just something to make it a bit farther from the world your audience is in.

    I’ve read books like that – the “Hero” series by Moria J Moore is a fantasy with magic, a pre-industrial level of tec and a Landing Day celebration of when their ancestors ‘came from the stars’. The Final Fantasy series of video games is guns ‘n swords tec with battle magic – but many of the plot elements are common in the SciFi genre (experiments on soldiers, killer asteroids)

  8. @ Esther
    You may consider dressing Imaginary History it up in fantasy tropes a “fix” — but to me, what you suggested sounds like having Pat’s sister came over and paint one of her murals over top of my hardwood panelling to make it look better. The murals are awesome… but they would do better on a different surface. And the hardwood is also lovely in it’s own way, it deserves the chance to be appreciated for what it is.

  9. @Michelle

    Not what I meant. Its just that both of the examples I used were Fantasy/SciFi elements. Try some descriptions from Film Noir or Western. Scan National Geographic or the Discovery Channel for weird/beautiful/unusual places or customs to give your story an “other” feel. Have your people run afoul of a odd or unusual law. You don’t want a “Not in Kansas” effect – just a subtle hint of unexpected flavor. (like apple pie at a excellent restaurant)

    If you want some more examples – its like….
    – when I cook and add a pinch Cinnamon to a pot of Cheddar Potato soup.
    – when I act and put a momentary stillness by an action I wish to emphasize.
    – when I paint a blue object and tint the shadow green to add depth.

    This blog post we are commenting on is all about the difference between Necessary and Sufficient causes. What is necessary for a reader to enjoy a book? That is easy to spot when it it wrong. (plot, grammar, characters….)
    What is sufficient for them to enjoy the book? Well, you could give them exactly what they thought they were gonna get. (Romance novels are a good example) Or you can surprise them enough they don’t mind its not what they expected. You are describing a problem with your book that it is not ‘expected’ but not particularly different either.

    I remember reading those Alexander Lloyd books. What I recall most about them was all the times I giggled and thought “That is just like the western/travel/spy story I read!”. I spent so much time trying to recognize all the stuff in those adventures. 😀

  10. @ Esther
    I am very curious as to what I said that convinced you that my story was “not particularly different”.

  11. @Michelle
    “Unfortunately I have exactly the problem described above when trying to figure out how to do anything with those stories. They just don’t *fit* into an established genre.”

    Imaginary History stories (and I can think of only a few) are pretty rare. All the ones I remember played around with many tropes rather then *almost* fitting in a particular genre. Each one reminded me of a quilt or montage. They were very simular to Reality Fiction – but kept adding little unexpected hints that made me want to keep watching (or reading, or listening) so I could figure out what was different.

  12. @Esther

    You appear to have concluded that my statement regarding the fact that certain of my stories “didn’t fit into an established genre” was me trying to express a writing problem that I wanted/needed help with.

    I am sorry if I was unclear, but what I was actually doing was whinging over the state of the universe, not the state of my writing.

    I appreciate your desire to be helpful.

  13. @Esther

    I like your distinguishing ‘not in Kansas’ from something just strange enough to avoid the Uncanny Valley.

    I expect examples of both degrees of strangeness — and some in between — could be found in Pullman’s HIS DARK MATERIALS. The daemons would be a ‘not in Kansas’ difference; the slightly different terms for common things (eg ‘chocolatl’) are less impressive.

    I’d like to mirror some of your remarks on my LJ.