Simply put, a book's primary conflict (also sometimes called the central conflict) is the problem or question that's raised toward the beginning of the book and resolved at the Resolution.
Incognolio by Michael Sussman. Problem: The nonsense word incognolio is stuck in the Author's head and won't leave. Question: Will the Author discover what incognolio is and finish his book?
Parable of the Sower by Octavia Butler. Problem: Olamina's community is in constant danger. Question: Will Olamina survive and find or create a safer, more stable community?
Labyrinth (1986 film) by Jim Henson. Problem: The Goblin King has stolen Sarah's baby brother, Toby. Question: Will Sarah solve the Labyrinth in time and get Toby back, or will Toby be turned into a goblin?
My understanding of a book's primary conflict affects the way I construct a reading of the manuscript as a whole and often provides information crucial to a) understanding why certain elements aren't yet gelling, b) proposing solutions, and c) recognizing opportunities to make the book even more impactful. How does it do this, and what kind of information do I glean from it?
It defines the scope of the book.
The primary conflict is what drives the narrative arc - it is what's being set up in the setup; it's what the main character must engage with as they move into the rising action (or the descent into hell, depending on the model you're using); it's what's resolved at the book's Resolution - and therefore it roughly defines where the book should begin and where it should end. It determines the boundaries of your narrative. If your book is a house, the primary conflict is the foundation.
If the book's opening pages don't grab me, I look for hints of the primary conflict. If there aren't any, it could be that the book opens too early or that hints of the primary conflict need to show up earlier. If the book feels like it loses focus or drags on too long at the end, I look at where the primary conflict was resolved and how. Was the narrative arc satisfied fifty pages ago? The denouement should be tightened up. Or maybe the primary conflict introduced in the beginning was actually resolved around the midpoint and a new conflict with the same characters introduced, in which case it'll feel like two books smashed together. (For a hilarious example of what this looks like, see the MST3K version of the movie Riding with Death.) In cases like these, the solution could be to reframe the primary conflict so it encompasses all the events in the manuscript or to divide the manuscript up into two shorter books.
Sometimes I find that the primary conflict isn't resolved in the manuscript at all. This is an especially common pitfall when writing a series; it's easy to get wrapped up in the series conflict and forget to identify this book's primary conflict. The series conflict should definitely show up in Book 1, but it won't be resolved until the last book in the series, while Book 1 is going to have its own (but related) problem that will be resolved. As a simple and general example: If the series conflict is Stopping the Antagonist, then maybe Book 1's primary conflict is Temporarily Neutralizing the Immediate Threat, which is resolved in Book 1 for good or ill - either the MCs neutralize the threat, or The Thing We Don't Want to Happen happens. Or maybe Book 1's primary conflict is about identifying the antagonist, and the MCs learn who the antagonist is at Book 1's Resolution. Maybe they only learn in Book 1 that there *is* an antagonist who was responsible for setting into motion The Thing We Don't Want to Happen, and the work of Book 2 is figuring out who the jerk is and why they're trying to ruin everyone's life. Point being, though, that there's a problem raised and solved in Book 1 that's related to the bigger series conflict.
It drives your book's narrative arc and is therefore a crucial component of the book's structure.
I touched on this in the previous point, but here I take it further: all five major plot points in a book's structure need to relate to its primary conflict, which means we can use our understanding of the primary conflict to identify and problem-solve around the major plot points.
For example, could the Darkest Moment be even darker? It will only feel like a Darkest Moment if it looks, for at least a second, like there won't be a triumphant resolution to the primary conflict. So if your primary conflict is about Stopping the Antagonist, a dark moment wherein your MC is about to die will only feel like the Darkest Moment if your main character is the only one who can stop the antagonist. If there are allies who could conceivably pick up the mantle after the main character dies, then all is not lost, and the stakes could be even higher.
It can help answer questions about the book's genre.
Another common pitfall is getting confused about the book's genre when there are two strong plot lines. This is most common when one of them is a romance plot. If your question is something like, "Is this a fantasy with a romance subplot, or is it a romance in a fantasy setting?" look at the conflict that drives the book's narrative arc. If the problem raised in the beginning and resolved at the Resolution is, "How will these characters fall in love and find a way to be together?" then it's a romance in a fantasy setting. If it's something else, then it's a fantasy with a romance subplot.
Once you've identified the genre, you can adjust your book's structure (and query letter or book blurb) to better align with it, thus sending a clearer message to anyone who reads it just what kind of book this is.
It provides information that can be used to increase or decrease a novel's word count.
There are a couple parts to this point: subplots and scenes.
First, subplots. Your novel's primary conflict is the maypole around which to wrap your subplots, which should all act either as catalysts or obstacles - or both - to the primary conflict. A couple of examples:
1. In Pride and Prejudice, Lydia and Wickham's elopement acts as an obstacle to the romance between Lizzy and Darcy (and comes at a brilliant time, just when things were going so well!), but it also acts as an aid because Darcy's involvement in the scandal gives him an opportunity to show real growth and cement Lizzy's love for him. (I'm convinced that if he hadn't acted but instead had gone back to his friends and let the whole thing alone, she'd have gotten over him.)
2. In The Princess Bride, Buttercup's impending marriage to Prince Humperdink is a threat to the romance with Westley (obstacle), but it's also what gets him to come back to land (aid). (Like, in all those years he couldn't have sent a single message saying he was all right and working on getting back to her? Rude.)
So what does this have to do with word count? If you're looking to add words, then look for ways to further connect the subplots to the primary conflict. Can they intersect it more? If they're acting as aids, can they also act as obstacles (and vice versa)? If you're looking to cut word count and one or more subplots are not intersecting with the primary conflict at multiple points throughout the story and acting as either obstacles or aids to it, consider cutting them.
Second, and on a related note, you can find ways to cut words by identifying scenes that don't do (enough) work toward the primary conflict and hence can be cut or combined with other scenes to do more work.
When should you think about your primary conflict?
If you're a plotter, then the primary conflict should be one of the first things you determine, since it'll direct so many other decisions about your book. If a pantser like me, then unless you're working in a genre with a set primary conflict, such as romance or murder mystery, you'll probably identify your primary conflict after you've written your discovery draft and can use it to direct your first revision.
These are just a few of the ways in which the primary conflict helps me construct a reading of a manuscript and dig into the opportunities to strengthen it. If you have other ideas or any questions or comments, please leave a comment below!
Want more discussion of conflict in fiction? Check out the Novel Approaches podcast Episode 007: Conflict, wherein author r.r. campbell and I discuss what conflict is, why it’s important, and how we can use it to fuel our stories.