Zinneman called it a ‘necessary evil’ and wordsmith par excellence David Mamet says: “A good film script should be able to do completely without dialogue.“ I am not an expert, not even a native English speaker and I most certainly lack a deep knowledge of vocabulary. My passion is for story and structure. So much for the disclaimers.
But as you’re asking about dialogue, here are some principles that I have observed in great screenplays. And yes: more often than not when writers draw the attention to their dialogue, the story doesn’t work.
These twenty tips are not exhaustive, there are probably another ten major principles and fifty equally valid minor rules of thumb. And each has probably been breached beautifully at some point in great movies.
Feel free to add more or argue any or all of these in the comments.
1. it should never – even remotely – smell like exposition.
2. it should support the subtext, the characters’ secret objective(s).
3. its grammar should be organic and deficient, not perfect.
4. its semantics should be meticulously shaped.5. it should be composed to support the scene’s intended rhythm.
6. it should not sound theatrical unless the character or genre warrants this.
7. lines should get shorter, punchier towards the end of the scene.
8. different characters should have different ‘idiolects’.
9. long dialogue should be broken up by characters’ responses, action etc.
10. avoid talking heads: give characters ‘something to do’ while speaking.
11. strong lines mostly deliver their ‘beat’ at the very end.
12. dialogue shouldn’t open nor end scenes (the latter not a hard rule).
13. characters shouldn’t tell each other what we have already seen.
14. no parentheses unless the line doesn’t work at all without.
15. when a character asks a question, don’t answer it directly.
16. numbers should be spelled out in full.
17. characters should not say exactly what they feel (except in PP2).
18. only use in-jokes, innuendo etc. if the audience understands.
19. avoid tongue-twisters, clever dialogue or lines that stand out.
20. avoid dialogue that only great actors can deliver credibly.
The last two clearly show this is all about spec screenplays by writers who still need to prove themselves. Once you’re up there, you set your own rules. And even then, there are exceptions. Look at the dialogue in Juno. It draws so much attention to itself that some thought those first couple of minutes were borderline indigestible.
Diablo Cody got away with it.
Each principle above is a challenge in itself. That is why often at the very end of your development, when you are tantalisingly close to the final draft, a ‘dialogue pass’ helps making sure every line and every word hits the mark.
Beginning screenwriters can’t always judge whether their own dialogue really works. That’s why it is essential to have a professional do a final polish of your work before you send it out, even if the story works.
Then again, you can avoid all the hard work as tip #20 holds the easy solution to all your dialogue problems.
Just spend an extra ten million on your cast.