Commentators on screenwriting use a variety of terms to refer to that core aspect of the screenplay that needs to be present in all the relationships and action in order to give the screenplay a sense of unity. You might call it theme, or premise, or main problem, or controlling idea. I even recently heard it referred to as the “game” at the centre of a story.
Master Myth and Derivative Myth
Canadian professor of sociology, Gérard Bouchard, describes a core aspect of a society’s identity as its Master Myth. This is a set of values, relatively stable over time, that describes the foundation of a particular society’s culture. It lies at the heart of a society’s social, political and cultural life, and provides a sense of unity and continuity. These basic values, which inform a society’s attitude towards big issues such as the economy, immigration, sexuality, religion and so on, remain stable over relatively long periods of time, but every generation or two they manifest in new ways, which Bouchard calls Derivative Myths. So, for example, the American master myth might be expressed in terms of individualism, freedom, enterprise, self-determination, and so on. In the past, the derivative myth was expressed as the need for government to ensure that individual citizens were able to enjoy freedom, whereas nowadays, the same basic values are expressed in a derivative myth of a more laissez-faire nature, in which government intervention is frowned upon. Same values, different expression.
Master Conflict and Derivative Conflict
For a story to work as a screenplay, it has to be seriously compressed. There’s only so much screen time to fill, and only so many scenes in which to do that. As a result, the more each element of the screenplay focuses on the same idea, the more coherent and focused the screenplay becomes. Using Bouchard’s idea as an analogy, I find it helpful to look at my writing with this question in mind: What is the Master Conflict here? What is the problematic issue all the characters must relate to in one way or another? What is the basic conflict that returns in various different guises, or Derivative Conflicts, in every scene? Here’s an example.
Towelhead

....................GAIL
...............(stares at her, sharply)
..........The bottom line is this, Jasira:
..........When Barry offered to shave you,
..........you should have said no. There
..........are right ways and wrong ways to
..........act around men, and for you to
..........learn which is which, you should
..........probably go live with one.
Gail's anger almost masks the primal vulnerability she hates that she's feeling right now. Almost.
So here’s my version of the master conflict under scrutiny in this film: Every individual struggles to regulate their instinctual sexual needs according to agreed social norms. These three elements, the individual, their sexual needs and society’s norms, form the ingredients for all the specific (“derivative”) conflicts that play out in this film. The main character, thirteen-year old Jasira, is confused by the conflicting messages she receives about her sexuality. She encounters older predators, in the form of her mother’s boyfriend and her father’s neighbour, who are unwilling or unable to regulate their sexual instincts. Their derivative conflict is that of a sexually active adult confronted with the temptation to abuse a trusting, naive child. Jasira encounters an opposite, severely repressive attitude from her conservative Lebanese father, who viciously condemns her sexual explorations, while giving free rein to his own in a new relationship. His derivative conflict is his struggle with his repressive cultural heritage and his individual need for a fulfilling sexual relationship. Jasira encounters a more progressive, but wary position in her father’s other neighbours, a heavily pregnant woman and her husband, whose derivative conflict is this: they are aware of cultural differences regarding sexual norms, but they refuse to go along with Jasira’s father in his shame-driven blaming of the victim.
Master Conflict: The Thematic Core Of A Screenplay
