You get the idea from screenwriting teachers like John Truby and Chris Soth that script writing is essentially a left-brain activity—one requiring extensive pre-planning. For Truby, it’s a 22 step method. For Soth, it’s eight. Even Syd Field’s method requires the author to know, at the outset, the beginning, the end and two plot points.
All these methods represent an extreme left-brain approach to writing—one that makes genuine creativity difficult, if not impossible. It’s not that the conscious mind should not enter into the creative process. It’s just that, as Walter Kerr said, it should “arrive late and tidy up.” How Not to Write A Play (Dramatic Pub Co 1998) p. 40
Besides advocating that the author know the plot ahead of time, some screenwriting teachers claim that the writer should begin with a thesis or, as Lajos Egri would say, “premise.” In The Art of Dramatic Writing, theater director Egri maintained that every play can be reduced to some aphorism such as “true love never dies” for Romeo and Juliet. That’s the play’s premise, which the playwright should keep in mind when writing a play. Likewise, John Truby, in Anatomy of Story: 22 Steps to Becoming a Master Storyteller, speaks of making a “moral argument.” But whatever terminology they use, they’re saying the same thing: A play or screenplay should try to prove something, and the author should consciously shape the material to fit that proposition.
Ibsen wrote this way in his thesis plays, but this method is contrary to the way most fiction writers work. Most fiction writers start a story, not with a thesis (true love never dies) or even a theme (love), but rather something much more specific: an image, a situation, or even a phrase. Walter Kerr, who advocates this method, speculates that, when writing The Glass Menagerie , Tennessee Williams may have used the phrase “gentleman caller” as his starting point.
Emlyn Williams, in Volume 1 of his Collected Plays describes how he starts a play: “[M]y mind is set ticking by a book I have read, or even a chance remark, a face on the street." He sketches the characters and christens them in a dramatis personae, before writing a short synopsis of no more than five hundred words. He then makes notes on such matters as dialogue, phrases, props, etc. and proceeds from there.
John Braine, in Writing a Novel pp17-18, speaks of a picture emerging. He starts by seeing some part of the novel. It needn’t be, but, for him, it's always the end. “It isn’t an idea that visits me,” he adds, “ because that’s abstract. It’s a picture of something happening to somebody.”
As these writers attest, creative writing is, for the most part, a right-brain activity, one for the unconscious mind. The rational mind has a role in the creative process, but that comes later, when it’s time for editing and rewriting. Then, as Kerr put it, the rational mind “arrives late and tidies up."