Prisoner's Dilemma

Prisoner's dilemma

Here's the scenario. Suppose you and I are prisoners who have committed a crime together, have been caught, and are now being held in separate rooms.

The prosecutor presents you with these options:

1. If you confess and I don't, you go free and I'll get a five year sentence.
2. If I confess and you don't, I'll go free and you'll get a five year sentence.
3. If we both confess, we'll each get three year sentences.
4. If neither of us confesses, we'll each get one year sentences.

He says the same to me.

Here's a graphic way of representing our options (your choices and outcomes are in blue, mine are in green; when two outcomes are in the same box, those the outcomes for the row player -- in this case, you -- come first and those for the column player -- in this case me -- come second):

You should make your choice in the light of the following considerations:

• Neither of us cares much about the other; we're just partners in crime.
• Each of us can avoid the other in the outside world.
• The prosecutor won't let us communicate with one another before choosing whether to confess.

That's all the information you get.

Now, make your choice: Confess or Don't confess.

NB: You can skip ahead to my analysis of the game, but I think that it's much easier to understand if you play two rounds.

Prisoner's dilemma