To a certain section of the population, the first word of the title should give you a fair idea of the topic of this post. 🙂
There’s a memorable scene in The Princess Bride where the mysterious Man in Black engages Vizzini in a battle of wits in the form of which-cup-is-poisoned? Naturally, Vizzini (having been established as not as clever as he thinks he is) falls into the trap and drinks the poison, and the audience learns how he was duped.
I was reminded of this scene by the similar scenario presented at the end of the first episode of Sherlock (“A Study In Pink”). It differs in that it is the hero facing the choice of two options (and doesn’t use glasses of wine, though I will for the purpose of simplifying the discussion), but otherwise the same general scenario is presented, to wit:
- there are two glasses of wine
- one is in front of each person
- one is poisoned
- the challenger knows which is which
In the scenario as presented, the challenge becomes like a game of poker between the two. Did they poison my glass, or are they bluffing? Vizzini goes to ridiculous lengths of imagining bluff and double-bluff. Sherlock largely focuses on his opponent to try to gauge his tactics.
Despite the fact that Sherlock Holmes is, unlike Vizzini, about as clever as he thinks himself to be, he still makes the same … elementary … mistake. Fortunately, he gets away with it, as a third party interrupts the “game”, but he (and the audience) never finds out for certain if he chose rightly or not.
So what is this simple mistake? In a battle of wits, don’t freely accept statements made by your opponents. Granted, in Sherlock’s case his deductions confirm the truth of some of his adversaries claims, but that doesn’t justify accepting everything as presented. This is a life-and-death scenario—your opponent is aiming to kill you, so why wouldn’t they lie?
Often, such things can be explained away by the demands of narrative, but in this case it doesn’t make the scenario less interesting. In The Princess Bride we see one of the possible alternatives to the scenario as presented*. If the challenger is less than honest about the scenario, then the possibilities are:
- The subject’s glass is poisoned
- The challenger’s glass is poisoned
- Both glasses are poisoned, and the challenger has an antidote/immunity
- Neither glass is poisoned; the whole game is a distraction
Now, it’s reasonable to assume given the outcome that Sherlock was facing either possibility 1 or 2, but during the game it would be foolish not to consider the possibility of 3 and 4. Vizzini didn’t, and fell foul of 3.
Interestingly, I haven’t encountered possibility 4 anywhere; I’d be interested if anyone else has.
* I’m impressed by the fact that the Man in Black implies the potential of 3 and 4 in his presentation of the scenario (“Where is the poison? The battle of wits has begun. It ends when you decide and we both drink, and find out who is right and who is dead.”—emphasis mine). He never claims that one glass is poisoned and the other is safe. Conversely, Sherlock’s adversary states explicitly that (“There’s a good bottle and a bad bottle. You take the pill from the good bottle, you live; take the pill from the bad bottle, you die.”).