You and I play a game. We each want to get a big score. But we do not care if the other person gets a big score.
On each turn, we can each choose to Give or Take. If I Give, you get three points. If I Take, I get one point. If you Give, I get three points. If you Take, you get one point.
If we both Give, we both will have three points. If we both Take, we both will have one point. If you Give and I Take, then I will have four points and you will have no points. If you Take and I Give, then I will have no points and you have will four points.
We would both like it if the other person would Give, because then we get more points. But we would both like to Take, because then we get more points.
I would like it better if we both Give than if we both Take. But if I think you will Give, then I would like to Take so that I can get more points. It is worst for me if I Give and you Take. And you think just the same thing I do — except with “you” and “me” switched.
If we play over and over again, then each of us can think about what the other has done before. We can choose whether to Give or Take by thinking about what the other person has done before. If you always Give — no matter what I do — then I may as well Take. But if you always Take, then I also may as well Take! (And again, you think just the same that I do.)
Why would either of us ever Give? Taking always gets more points. But we always want the other to Give! And if we both Give, that is better for both of us than if we both Take. Is there any way that we could both choose to Give, and not be scared that the other will just Take instead?
Also, if we just know how each other thinks (we don’t have to think the same) and I can show for sure that you will Give to me if I Give to you and that you will Take from me if I Take from you, then I will Give to you.
Prisoner’s Dilemma
You and I play a game.
We each want to get a big score.
But we do not care if the other person gets a big score.
On each turn, we can each choose to Give or Take.
If I Give, you get three points. If I Take, I get one point.
If you Give, I get three points. If you Take, you get one point.
If we both Give, we both will have three points.
If we both Take, we both will have one point.
If you Give and I Take, then I will have four points and you will have no points.
If you Take and I Give, then I will have no points and you have will four points.
We would both like it if the other person would Give, because then we get more points.
But we would both like to Take, because then we get more points.
I would like it better if we both Give than if we both Take.
But if I think you will Give, then I would like to Take so that I can get more points.
It is worst for me if I Give and you Take.
And you think just the same thing I do — except with “you” and “me” switched.
If we play over and over again, then each of us can think about what the other has done before.
We can choose whether to Give or Take by thinking about what the other person has done before.
If you always Give — no matter what I do — then I may as well Take.
But if you always Take, then I also may as well Take!
(And again, you think just the same that I do.)
Why would either of us ever Give? Taking always gets more points.
But we always want the other to Give!
And if we both Give, that is better for both of us than if we both Take.
Is there any way that we could both choose to Give, and not be scared that the other will just Take instead?
It would help if I knew that you and I think exactly the same way.
If this is true, then when I decide to Give, I know you will Give too.
Also, if we just know how each other thinks (we don’t have to think the same) and I can show for sure that you will Give to me if I Give to you and that you will Take from me if I Take from you, then I will Give to you.