Thursday, May 26, 2011

No shit, Sherlock!

I recently watched Sherlock, the recent BBC modern era take on the Great Detective. It was a lot of fun, and I'm looking forward to the next series. One thing that bugged me, though, was that Holmes's apparently incredible deductions are so often completely fallacious. (Mind you, the same was true when Conan Doyle wrote Holmes, so nothing new there.)

Here's an example. Holmes deduces that a dead man cannot have shot himself. He has a bullet wound in his right temple. However, everything in his home suggests that he is left-handed: he places his coffee on the left of his chair, he slices his bread from the left, his pen is on the left of his notepad, and so on. Consequently, if he had shot himself, he'd have used his left hand, and the wound would be on the left of his head, ergo someone else shot him. Genius!

Well, sorry, I call bullshit.

I'm left-handed. I slice my bread to the left. I place my pen on the left. I generally drink coffee with my left hand - but frankly, I'll put my coffee whichever side of the chair is more convenient. But, Mr Smarty-Pants Holmes, I fire a gun with my right hand, as shown below. As, indeed, do many left-handers. I also play guitar and violin right-handed, shoot a bow right-handed, and use a computer mouse right-handed.

Yes, Holmes turned out to be right, but for the wrong reasons, and in spite of his faulty logic.

I so often find that Holmes writers must be like people who design IQ tests. Holmes puts forward a logical theory based on what he observes, but that doesn't mean it's the correct one. For example, he deduces that Watson has returned from Afghanistan or Iraq, based on his posture and the fact that he has a suntan on his hands, and therefore he must be a soldier who has just served in a hot climate and got wounded. Again, Holmes turns out to be right.

But Watson could equally well have been serving in Belize, or an embassy in the Far East. Or have left the service some time ago and been working in a office abroad for a few months. And he could have been injured in an accident, not necessarily a combat wound. But we don't think of those possibilities when we're watching the show, we're too busy being dazzled by Holmes's cleverness.

Yes, I know they're just stories and I should just sit back and enjoy it, but that's not the way my brain works. I keep looking for other explanations of the data and alternative hypotheses. That's why I have so many problems with the aforementioned IQ tests - I can usually think of half a dozen equally logical different answers to the same question, and it turns into a guessing game as to which one the questioner had in mind.

Q: London, Munich, Moscow, Miami. Which is the odd one out?

Well, obviously London, as it's the only one that doesn't start with M. Or Miami, as it's the only one with only five letters. Or maybe Munich, as it's the only one without a repeated vowel. No, of course, it's Miami after all, as it's the only one not in Europe. Hang on, it's got to be Moscow - that's the only one that's both a city and a river. No, dammit, it is Miami. It's the only city that was founded by a woman. And it's the only one that's also a county. And the only one that's also a tribe, and a language. And the only one with a beach.

See what I mean? Just pick one: you've got a one in four chance of being right.

That's how Holmes feels to me. He's brilliant at unerringly picking the right answer out of all the possible ones, and annoyingly, he's right even when he's totally wrong. Just like these guys figuring out where the Riddler is going to strike next.


primaveranz said...

Re the guessing what the questioner meant..When I was a kid I was marked down when the teacher said "Which do you notice first in a Thunder storm? Thunder or Lightning?" I said "Thunder". She took great delight in announcing to the class that "John is wrong. "Lightning travels at the speed of light." She ignored my reply that I was usually indoors during a storm so never saw the lightning. You can tell I am still twisted and bitter about that! ;)

Matt Kelland said...

Yup. You answered the exact question you were asked. The teacher intended to ask you a different question.