Most films end up doing away with substantial portions of their script’s dialogue. The director eventually finds that lots of the story’s meaning is communicated or implied visually. The dialogue has become extraneous, unnecessary.
Consider:
From TALES FROM THE SCRIPT, Edited by Peter Hanson and Paul Robert Herman, HarperCollins, 2010, p. 170, screenwriter Andrew W. Marlowe described an example of how the script differs from the movie:
"There was this experience on AIR FORCE ONE, where I’d written this little speech. Harrison came up to me and he said,
"'It’s a great speech.'
"'I said, 'Oh, thank you.'
"He said, 'I’m not gonna do it. All this, I can do with a look.'
"And he could."
And there’s this from Alex Garland in SCREENWRITERS’ MASTERCLASS, Edited by Kevin Conroy Scott, Faber & Faber Ltd. 2005, p. 164:
"One of the things I definitely learned (from drawing cartoons) was how redundant dialogue can be at times. What you can do is rely on the image; (successful) comic books and films do this the whole time."
And later, on p. 165:
"There’s a terrific urge to overstate because you’re afraid that people will miss something, and when I look at 28 DAYS LATER, for example, which is the only screenplay I have ever written that went straight through to being made into a film, one of the things I think is tonally wrong about it is that it spells stuff out at times when it really doesn’t need to."
The problem is, screenplays, in their pre-film state, can’t rely on Harrison Ford’s “look.” They can’t always get things across that the eventual film, with ease, will do from within its visual, directorial, and performance arsenals. Worse, “spec” scripts from unproven screenwriters must get their stories across to an agency or studio reader already biased by the writer’s lack of experience. Yet those specs are held to the same standard.
Screenplays must communicate their meaning fully and clearly or risk losing their reader and the sale because of the potential casting of somebody like George Spelvin (non-actor extraordinaire), rather than Harrison Ford, not to mention other deficiencies like insufficient information, critical logic lapses, or merely a lack of emphasis. It may look like a duck, it may walk like a duck, but on the page, until it talks like a duck, it ain't a duck!
It recalls that old story about the blind men and the elephant: each man identified a different object as he touched some part of the beast. None “saw” the elephant. At least in the movie version of the fable, until they get Harrison Ford or Steven Spielberg, they’ll have to rely on the script. And, to all the spec writers out there, if that doesn't work, may the Ford be with you!