Doc

To Doc, a white-haired surgeon, the poker table’s a stage. He prepares bits for the table and even brings a prop every now and then, as when he pulled out what appeared to be an exceptionally tiny condom and gave it to another player.

Thus, when he asked the table if we believed in telepathy, I had an inkling it was more than idle speculation. “You know,” he elaborated, “the ability to read people’s minds.”

Jack, a bookie whose sense of odds outstrips his sense of irony, said that was all bullshit. Doc inquired if, in that case, he’d like to bet on whether Doc could guess a number he chose, one through 30. After a bit of negotiation they agreed to bet $300 with the following stipulations: Jack would tell him if the number was over or under 15, and he would think of the number as Doc read his mind.

With that worked out, Jack wrote a number on a piece of paper. Doc closed his eyes, rubbed his temples, and after a little while said, “Eight.” Jack tossed his folded-up paper onto the table in disgust. Another player unfolded it, and sure enough, eight. Jack reached into his pocked and forked over three $100 bills.

I don’t know how he did it, but I wasn’t surprised Doc guessed the number. The situation reminded me of two stories. The first is from Nassim Taleb’s book The Black Swan. He describes a situation where a coin is flipped 99 times, landing heads each time, and imagines asking a variety of people the odds of the next toss landing heads. Someone who hasn’t been educated about probability will likely say the odds are much better that it will be tails, because it must be tremendously unlikely to flip 100 heads in a row. Someone who knows a little more about probability will recognize that each flip is an independent event and therefore there is still a 50/50 chance of heads on the next flip. But a smart gambler will recognize that if the coin landed on heads 99 times in a row, it probably isn’t a fair coin.

The second is a riddle I read on a chess website. A man is telling his friend a story. It goes as follows: an old man is sleeping in church. He dreams that he is caught up in the French Revolution and about to be guillotined. At that moment his wife pinches him on the neck to wake him up, but the shock is so great he has a heart attack and dies on the spot. The friend says, that story can’t possibly be true. How does he know?

This riddle stumped a lot of smart chess players.  The answer is that, as the man died in his sleep, he couldn’t have told anyone about his dream. I would bet that a group of English majors would be much more likely to solve it than a group of engineering majors. Anyone who’s interested in story telling will be struck by the seemingly extraneous layer of framing in the riddle (“A man is telling…”). This makes the story longer and harder to follow, but doesn’t seem to add anything, so why include it? That line of thinking leads quickly to the answer.

Even though I knew the odds of someone randomly guessing a number between one and 30 are low (one out of 30, in fact), I had no intention of taking the bet, because the fact that Doc was offering the bet and invoking all the tropes of a magic act suggested something was up. I was mildly surprised Jack took the bet, and a lot more surprised when he ran it back for $500. The second time the answer was seven.

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