A prisoner’s dilemma cheat sheet

Because cooperation is hard.

Prisoner’s dilemma is a strange but fascinating thought experiment / game that can teach us all why some strategies for cooperation are better than others.

Imagine two people being questioned about the same crime. They’re each talking to the interrogator separately, and the interrogator gives each person the same deal: they can choose to vouch for the other person’s innocence or guilt. And of course there’s a twist. If both people vouch for each other’s innocence, they’ll each get 3 months off their sentence, but if the first person vouches for the second person’s innocence, and the second person claims that the first person is guilty, the first person will get no time off their sentence and the second person will get 5 months off their time. Lastly, if they both say the other is guilty, they each get 1 month off their time.

It ends up working like this:
Innocent + Innocent= 3 month reduction each
Innocent + Guilty = 0 month reduction for first person, 5 for other
Guilty + Innocent = 5 month reduction for first person, 0 for other
Guilty + Guilty= 1 month reduction each

The reason this is tricky is that if you know what the other person is going to do, it’s always…