Technology

Yes, that’s a more correct use of “prisoners dilemma:” a choice to either cooperate or defect. Origin below, for the curious.

The dilemma

Two prisoners are interrogated in separate rooms. Each is asked to snitch in exchange for a reduced sentence.

Because they’re separated, the prisoners can’t coordinate, but each knows the other is offered the same deal and the interrogator will only offer bargains that increase their combined years of imprisonment.

For example, “house wins” if snitch gets -2 years and snitchee gets +3 years, since interrogator would net +1 year from the deal.

So what will each prisoner do?

The result

Of course, the best outcome overall is for neither to snitch, and the worst is for both to snitch.

The Nobel-Prize-winning observation was that any prisoner faced with this dilemma (once) will always net a lesser sentence if they snitch than if they don’t, no matter what the other decides.

In other words, two perfect players of this game will always arrive at the worst result (assuming they only expect to play once). This principle came to be known as the Nash equilibrium.

Applications

The result above sounds bleak because it is, but real-world analogs of this game are rarely one-offs and thus entail trust, mutuality, etc.

For example, if the prisoners expect to play this game an indeterminate number of times, the strategy above nearly always loses (the optimal strategy, in case you’re wondering, is called “tit-for-tat” and entails simply doing whatever your opponent did last round).

The study of such logic problems and the strategies to solve them is called game theory.

Edit: fixed typo, added headings and links