Every writer has been there: you're reading back through your draft when you suddenly realize your protagonist walks into the villain's lair for... no apparent reason. Or your character refuses to make a phone call that would solve everything because... well, the plot needs them not to. These aren't just minor hiccups—they're logic gaps that make readers roll their eyes and close your book.
The culprit? Weak causality. And there's a deceptively simple technique that can help you catch and fix these problems before they undermine your entire narrative.
What is The Therefore/But Rule?
The Therefore/But Rule comes from the South Park creators Trey Parker and Matt Stone, who've used it to craft hundreds of tightly plotted episodes. The rule is elegantly simple: every scene should connect to the next scene with either "therefore" or "but"—never "and then."
Here's what that means in practice:
"And then" plotting: Character A does something, AND THEN Character B does something, AND THEN something else happens.
"Therefore/But" plotting: Character A does something, THEREFORE Character B must respond, BUT their response creates a new problem, THEREFORE Character C gets involved.
The difference? Causality. "And then" is just a list of events. "Therefore" and "but" create chains of cause and effect that make your story feel inevitable rather than arbitrary.
Why This Rule Exposes Plot Holes
When you can't connect scenes with "therefore" or "but," you've found a logic gap. It's that simple—and that powerful.
Let's say you're writing a mystery. Your detective discovers a crucial clue in Chapter 5. In Chapter 6, they go to interview a witness across town. Can you connect these with "therefore" or "but"?
Weak version: The detective finds a bloody knife AND THEN goes to interview the witness.
There's no causal connection. Why that witness? Why now? The detective could just as easily go get coffee or take a nap. The plot is moving forward, but nothing is driving it forward.
Strong version: The detective finds a bloody knife with the mayor's fingerprints on it, THEREFORE she rushes to interview the mayor's assistant who called in the tip, BUT when she arrives, the assistant has fled, THEREFORE she must track down the assistant's family.
See the difference? Each action creates a consequence that necessitates the next action. The story has momentum built on logic.
How to Apply The Therefore/But Rule to Your Draft
Here's your step-by-step process for using this technique to strengthen your manuscript:
Step 1: Create a scene-by-scene outline
You don't need elaborate detail. Just one sentence per scene describing what happens. For a novel, this might be 40-80 scenes. For a short story, maybe 8-15.
Step 2: Connect each scene to the next
Go through your list and literally write "therefore" or "but" between each scene, then complete the thought. Force yourself to articulate the causal connection.
If you find yourself writing "and then" or struggling to make the connection, mark that spot with a red flag.
Step 3: Fix the weak links
For every flagged gap, you have three options:
- Add information to the earlier scene that creates a clear cause
- Change what happens in the later scene so it logically follows
- Cut or combine scenes if there's genuinely no causal relationship
Let's work through a concrete example.
The Therefore/But Rule in Action
Imagine you're writing a romance novel with this sequence:
Scene 1: Emma argues with her boss about taking time off.
Scene 2: Emma goes to her sister's wedding in Colorado.
Scene 3: Emma meets Jake, the best man.
Try connecting these. What do you get?
"Emma argues with her boss about taking time off AND THEN goes to her sister's wedding AND THEN meets Jake."
Those are just events happening. There's no drive, no momentum. A reader could ask: "Did she get the time off? Why does that scene matter if she's going to the wedding anyway?"
Now let's revise with causality in mind:
Scene 1 (revised): Emma's boss denies her time-off request for her sister's wedding, THEREFORE Emma quits on the spot, BUT now she's unemployed and stressed about money.
Scene 2 (revised): Emma arrives at the Colorado wedding angry and anxious about her future, THEREFORE she drinks too much at the rehearsal dinner, BUT this makes her brutally honest when the cynical best man complains about love.
Scene 3 (revised): Jake is intrigued by Emma's drunken rant about why marriage still matters, THEREFORE he seeks her out the next morning to apologize for his cynicism, BUT Emma is mortified and tries to avoid him.
Notice how each scene now creates the conditions for the next? The plot holes have vanished because every action has clear motivation and consequence. The boss scene isn't filler—it establishes Emma's emotional state and raises the stakes. Her drinking isn't random—it's a direct result of her stress. Their meeting isn't convenient—it's earned.
Common Traps to Avoid
Trap #1: Confusing chronology with causality
Just because Scene B happens after Scene A doesn't mean they're causally connected. "The sun rose AND THEN I ate breakfast" isn't cause and effect—it's just sequence.
Trap #2: Forcing false connections
Don't twist your logic into pretzels trying to connect scenes that genuinely don't belong together. If you can't make "therefore" or "but" work, maybe those scenes shouldn't be adjacent—or shouldn't both exist.
Trap #3: Overusing "therefore"
Your story needs both "therefore" and "but." If everything goes smoothly from cause to effect, you don't have conflict. The "but" creates obstacles and complications that make stories interesting.
The Real Power of This Rule
The Therefore/But Rule doesn't just fix plot holes—it transforms how you think about storytelling. Instead of asking "What happens next?" you start asking "What must happen because of this?" and "What could go wrong?"
This shift creates stories that feel tight, purposeful, and satisfying. Readers might not consciously notice the strong causality, but they'll feel it. They'll trust you more as a storyteller. They'll stay up past midnight because they need to know what happens—not what happens next, but what happens as a result.
Your Next Steps
Pull out your current work-in-progress and try this exercise on just one chapter. Write out each scene in that chapter, then connect them with "therefore" or "but." You might be surprised by what you find.
The gaps you discover aren't failures—they're opportunities. Every weak link you strengthen makes your entire narrative more solid. And the best part? This technique works whether you're a meticulous plotter or a discovery writer. You can use it to plan ahead or to diagnose problems in your draft.
Strong stories aren't just a series of cool scenes strung together. They're chains of cause and effect that feel both surprising and inevitable. Master that balance, and your readers won't be able to put your story down.