Mind & Body

The Prisoner's Dilemma Shows the Hazards of Selfish Thinking

You'd think that in any given situation, acting in your own best interest would get the best possible outcome for you. But that's not always the case. The prisoner's dilemma, one of the best-known examples from a field called game theory, shows that sometimes, doing what benefits the group is the best approach for the individual — but that's easier said than done.

Related Video: How Can You Win the Prisoner's Dilemma?

Here's the Dilemma

Say Joanie and Ashley are suspected of stealing Nikola Tesla's death ray. Reuben, the prosecutor, interrogates them in separate holding cells and gives them both the same offer. They're free to confess or stay silent, but if one confesses and the other stays silent, the confessor's charges are dropped and the other gets a year in prison. If Joanie and Ashley both confess, they both get probation. If neither confesses, they both get six months in prison. What should Joanie and Ashley do so that each of them gets the best possible outcome?

The "dilemma" in the prisoner's dilemma is that each person is better off confessing than remaining silent, even though what they'd get if they both confessed is worse than what they'd get if they both stayed silent. That's because if Ashley confesses, she'll get probation at the worst and dropped charges at the best, but if she stays silent, she risks a year stuck in prison while Joanie travels the world sampling exotic ice creams. Same goes for Joanie. It doesn't matter what the other person chooses; for the best (or in this case, least bad) outcome, both should choose to confess.

Real World Dilemmas

The prisoner's dilemma pops up all over the place in the real world. Every time rival companies decide what to charge for a product, they have to wrestle with the fact that both are best off setting a low price (since one high and one low will be bad for the high-price company, but two low prices will be less bad for both). Same goes for geopolitical issues — Brexit, anyone?

One fascinating way the dilemma played out happened on a British game show called Golden Balls. The show starts with multiple players that are gradually whittled down until two players and a sizeable sum of money remain. In the final round, the players are presented with two balls: one says "split" inside, the other says "steal" inside. If the players both choose "split," they split the money; if they both choose "steal," they go home with nothing. If one chooses "split" and the other "steal," the stealer gets all the money and the splitter gets nothing. It's a classic prisoner's dilemma, except the two "prisoners" get to talk about their decisions before they make them. And just like the classic dilemma, the players are best off splitting the money — which, most times, they agree they'll do, only to have one defect and leave with everything.

Once, though, a player named Nick convinced a player named Ibrahim that he was going to choose "steal," and that if Ibrahim chose "split," he'd split the money with him after the show. After some heated debate, Ibrahim agreed to choose "split" — only to have Nick choose "split" after all. His bluff was the only way he was sure Ibrahim would go his way. Don't hate the player; hate the game.

Watch How It Happened:

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Understand how game theory shows up in the evolution of life in Richard Dawkins' international bestseller, "The Selfish Gene." We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Hamer August 31, 2017

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