I blabbed on last time about characters. This time I wanted to scribble a few thoughts on motivation. To be specific, one less-than-desirable kind of motivation that crops up all over the place. While it's most noticeable in films and television, you can also find it in books, and in several graphic novels.
I've come to call it the insanity defense, and like most times you've heard this phrase invoked, it's still a cheap cop-out. The insanity defense is when the police detective, the brainy college girl, the private investigator, the spunky reporter, Shag, Scooby, and the rest of the gang have spent the entire story chasing a killer. It's not always a killer, mind you. Might be a serial rapist, a stalker with hopes for the big leagues, something like that. Anyway, they run down clues, have close calls, and spend the whole time trying to make sense, one way or another, of what's been happening. And finally, at the end, the mysterious killer is cornered and his secret layed bare for all to see.
Yup. Mad as a hatter. That's why the killer kills people.
That's why he wears the mask, laughs at the sight of blood, and played all those mind games with the police. It's also why he disguised himself as a woman, left the poetry-based clues, used only a 1967-issue fire axe to commit the decapitations, cries for his mommy when he gets shot, and only listens to punk music. It's also why he's able to ignore being shot seventeen times and stabbed nine, walk through an inferno, slip through holes smaller than shoeboxes, hold his breath for twelve minutes underwater, move faster than the speed of sound, and apparently teleport just by moving back into a dark corner of any given room.
I'm not actually picking on any one real novel or film, mind you. Although I could pull up a quick list of at least a dozen stories I've read or seen in the past two years that fall back on two or three of these points. In at least half of them, the insane killer is a she, by the way.
This is probably the weakest motivation a character can have, because all it does is show the audience you couldn't be bothered to work out any real motivation. Why did he do all of this? He's insane. How did she manage to do that? Well, she's insane. That explains everything, right?
Well... doesn't it?
I know I'm in the minority, but I've never liked the movie Se7en for exactly this reason. As the screenplay by Andrew Kevin Walker progresses, the killer's methods and motives become more and more vague. John Doe (played by Kevin Spacey) goes from finding people who exemplify a sin and killing them, to making people exemplify a sin and killing them, and then it finally all resolves in a bizarre double-twist suicide-by-cop. It's one thing to find a grossly obese man who eats twenty-five pounds of groceries a day and say he embodies gluttony. It's another to decapitate a man's wife, show him the head, and then try to claim he embodies wrath because he kills you for it. There's no consistency in his method (and thus, his motive) and this glaring inconsistency, in my mind, overpowers the powerful performances by Morgan, Brad, and Gwenyth.
Now, this isn't to say insanity is a bad thing in fiction. It just isn't a get-out-of-jail-free card (or, as the fancy folks say, carte blanche) that lets you do whatever you want. Novels and films are filled with characters on the brink of insanity, or well past it. The thing is—they're still developed characters, not just a catch-all excuse for an explanation. Mrs. Rochester, Hannibal Lecter, Renfield, Tyler Durden, and of course the Joker. All of these folks have thought processes that don't quite jibe with the general public. However, they also all have distinct personalities and limitations. We'd all call foul if Hannibal Lector slipped out of a straight jacket by force of will, if Renfield survived falling ten stories and was still fighting, or if the Joker began butchering people and eating them with fava beans. Insanity doesn't make them superhuman, not does it make them completely irrational. To quote one madman, "Just because I'm crazy doesn't mean I'm stupid."
If you're just going to use insanity as an easy excuse for whatever your character needs to do, don't be surprised if people if people put your writing on par with April Fool's Day, Friday the 13th, or some other bad 80's horror film.