Oh, how I hated genres when I started writing. I mean, come on! Genres are everything that's wrong with modern movies. Instead of coming up with an original story, they shoehorn an idea into a narrow category that imposes all these rules on it and prevents it from ever being fun or interesting. My screenplays sure as hell were not going to fall victim to that kind of literary castration. I was going to invent a bunch of new, exciting, creative concepts that couldn't possibly bear simplistic labels like "comedy" or "drama" or "action."
So I wrote, like, three scripts. They all suck. I'm not talking "suck" in an "oh, it's just a first draft" kind of sense here; they're just plain bad, to the extent that I don't think it's even worth trying to rework any of them. (More about this here.) But hey, none of them could really be pigeonholed into one of those annoying "genre" things!
The script I'm working on now is the best one I've written. It's not perfect yet; it may never be. Just like I wouldn't expect to cook a world-class dinner the fourth time I picked up a chef's knife, I'm not holding my breath for unmitigated success on the screenplay that's only three away from being my very first.
This one is, however, firmly entrenched in a genre (action/adventure). So what does that mean? Did I, as so many others have in the past, need to take an artistic step backward in order to increase my odds of one day getting paid? Well... no. I really didn't. In fact, I'd say the current script is a hell of a lot more creative, intelligent, interesting, thematically solid, and emotionally accurate than any of the others. That's right! More interesting! Even though my only goal with the rest of them was to write something interesting. Crazy, huh.
So now for the denouement. (That's French for "the part where Velma rips the mask off the bad guy's face and he explains how he would have pulled off his whole scam if it hadn't been for those meddling kids.") Why did it work? What's so magical about writing in a genre? How many rhetorical questions can you pose before you have to resume speaking in the declarative?
The answer, I think, is relatively simple. It's about expectations. While the expectations of movies as a whole aren't all that clear, the expectations of individual genres are. Put another way, if your script has no genre, you have no idea what people will be expecting when they read it. They might toss it aside and say it's nowhere near as good as Braveheart or Goodfellas, and you can argue, no, that's not what I was going for at all... but too bad -- you didn't know what you were going for, so you didn't know what expectations you were building. But if you stick to a genre, your task as a writer is immediately clear: Figure out the expectations of your genre, and meet them.
It's not an easy task, obviously, but it's a lot more straightforward than just "write something interesting." Everything's relative, but "interesting" is a lot more relative than "exciting" or "funny" or "terrifying." Comparing Silence of the Lambs with Annie Hall, it's hard to say which one is more interesting, but it's pretty obvious which one is more terrifying and which one is funnier. That kind of clarity is especially important when it comes time to rewrite. If you've written a comedy and there are only three or four scenes that make you laugh, there's your rewriting goal. Action movie where the people are just sitting around talking most of the time? You know what to do. And so on.
Genres are also important because they provide a guide for what to borrow. And you definitely need stuff to borrow. Oh, yes you do. I'm not talking about dialogue or actual scenes or anything that specific. But general components like structure, characters, momentum... nobody creates these things from nothing. You need other movies in your genre for guidance, influence, and inspiration. If you wall yourself up in concrete and pretend that no movies exist outside your own imagination, and you're going to invent everything yourself, then what happens is that you borrow a ton of stuff without realizing it. That's definitely happened to me, and it's not good. You want to be fully aware of what you're borrowing; it's the best way to ensure that you can put your own spin on it. Much of the history of good movies vs. bad movies boils down to the difference between "uncomfortably close to Movie X" and "interesting twist on Movie X," and not being aware of your specific influences is a good way to end up with the former. Chinatown is a screenplay that everyone and their sister refer to as a paragon of original screenwriting, but the reason it's so good is because Robert Towne drew on plot conventions and characters from four decades of noir films. Then he put his own spin on it, which was the emphasis on real L.A. history. Do people call it a knock-off? Do they say it's just a retread of other movies? Of course not. But if Towne hadn't had all those direct influences to build on, Chinatown would have been just another shitty detective movie.
So, see, genres can be pretty darn helpful. And I think I'm done talking about them now.