The answer is the same as how the moral premise can help to write a good movie.
Think of this analogy:
A scene is to a movie, as a paragraph is to an essay, as a propositional statement is to a logical syllogism.
In a syllogism there is a propositional statement followed by one or more statements of evidence, ending with a conclusion. In a good syllogism the various propositional statements are RELEVANT to the argument, constituting together SUFFICIENT evidence that is generally ACCEPTABLE to the opponent, and include the best REBUTTAL arguments against the position. (Those are the four criteria of a good argument as constructed by T. Edward Damer.)
Essays (or any persuasive communication construction) are exactly the same. The essay sets out to tackle a position on a topic. Each middle paragraph should provide evidence that supports the final paragraph's conclusion.
In both the syllogism and the essay, there is a beginning (postulate), middle (evidence), and end (conclusion).
Do you see the story setting up in this way, scene by scene.
So, in a movie, the story BEGINS with a character with a problem (the postulate, or major premise of an argument.) The obvious physical problem is a metaphor for his psychological (or emotional or spiritual) problem. There really is only ONE problem that takes form in the physical realm and the psychological realm. That PROBLEM is the BEGINNING, or the syllogism's postulation, or suggestion that we have a topic confronting us that needs a solution.
The movie then begins to present evidence that pertains to the problem. In a well formed movie that evidence is RELEVANT, SUFFICIENT, ACCEPTABLE, and provides a good REBUTTAL with respect to reality as perceived by audience. This is the MIDDLE.
Taken all together, that evidence leads to a natural conclusion (or ENDING), and the story's resolution.
Now, if you don't quite get all that, please read it again, or ask a question. Because the next chunk of understanding is related to all that above.
So, the SCENE is just like the MOVIE, in that there is a BEGINNING, MIDDLE, and END, and because this is a movie that has a consistently applied moral premise, everything in the scene pertains to the same postulation, evidence, and conclusion, but just in smaller chunks.
In a recent blog post David Mamuet is quoted as summarizing a scene this way:
WE, THE WRITERS, MUST ASK OURSELVES OF EVERY SCENE THESE THREE QUESTIONS.
1) WHO WANTS WHAT?I might revise those somewhat this way:
2) WHAT HAPPENS IF HER DON’T GET IT?
3) WHY NOW?
1. Who wants what?See, the beginning, middle and end?
2. Why do they want it?
3. What happens if she doesn't get it?
Well, the answers to each of those questions resides in the moral premise statement. AND, each main character in that scene will approach and answer each of those questions with answers (e.g. actions) that are answered by the moral premise statement.
So, if the moral premise of a movie (and of a scene... and of each character) is:
Pride leads to destruction; but
Humility leads to life.
then the two characters in the scene are going to either be pursuing pride, or humility, or some position on a continuum between Extreme Pride and Extreme Humility, but not starting from or ending at the same point. (See my post on the Expanded Conflict of Values.)
Keeping it simple for this explanation, in a scene you have two characters in conflict. One is trying to resolve the conflict in the scene by seeking a position that satisfies his or her pride, while the other is attempting to resolve the situation using humility. But every step toward humility (by either character) leads to life, and every step toward pride (by either character) leads to destruction.
Notice I said "LEADS TO". By the end of the movie we might actually "see" life or destruction, but in a scene we'll just see a small snippet of or step toward one or the other, --which when taken in total will naturally end the movie on one note or the other.