Game Theory 101: The Prisoner's Dilemma

This lecture explains how to find the equilibrium solution to a prisoner's dilemma using the strict dominance solution concept. Just because an outcome is good for everyone involved does not mean that rational players will reach it!

[jonquist]

AHH MY BRAIN!!!! lol
The "cooperate" "defect" terms had me very confused for awhile. I thought they meant, "cooperate" with the police, and "defect" from telling the truth. But turns out it means maintain "cooperation" with with the partnership, or "defect" from the partnership. I don't remember why I was looking this up in the first place though. I just found a note I had written to myself a few months back that said only "Prisoners Dilemma" on it. But I'm glad I looked it up.

[Gametheory]

@1Themuffinman1 This is just a convention that existed long before I created the video. Personally, I think the "classic" prisoner's dilemma story is really silly, and there are plenty of better examples to use instead.

[jciljciljcil]

The first 1.5 minutes is crystal clear in explanation. The teaching weakness here is the introduction of the terms "cooperate" and "defect" at that point without explanation. It is obvious to the teacher and probably most watching this, it may not be obvious to the novice observer and could lend to confusion.

[sasimi]

You didnt state that they cant talk to each other. Its an important premise to make otherwise they might agree on not confessing

[simka]

It would make things immensely easier if you defined "cooperate" and "defect." I was utterly confused until I realized that the two terms mean the opposite of what they seem.

[Gametheory]

The "dilemma" is that cooperating with each other is better than being mean, but being mean is actually what happens. I agree that there is very little actual dilemma here precisely because of the dominant strategy. The stag hunt is a better example of an actual dilemma.

[fothinator]

Great vids...I came here from the trade tariffs vid where you mentioned the prisoners dilemma. The Italians have a way around this dilemma: you never rat on your friends, everyone gets pinched, you do your time, and back to business. If your friend walks they know he squealed, and they will..."take care of it" lol

[HeartsChelsea]

Ah thanks! For some reason it was really difficult to understand it when my professor was explaining this, but your video helps a lot.

[Gametheory]

@WITreasure If you are taking game theory, keep in mind that I have lectures that will take you all the way up to incomplete information.

[qwertyjulz]

Thankyou for the response! Your videos are very helpful!

[Gametheory]

@crescine They are just words to represent strategies. They could be "C" or "D" if that would help you. (But these terms are prevalent in the literature, so this comes at a cost.)

[jlou]

Thanks for this video, it's really helped me :)

[WITreasure]

THANK YOU SO MUCH! You did a better job than my uni lecturer!

[rph]

@sappytortoise I believe the statement was "Rational players by rule never play the strictly dominated strategy". The last 'd' in "dominated" wasn't pronounced to distinctly.

[Warrantti]

To sum up in one sentence prisoner´s dilemma is about conflict between individual incentives and joint incentives.

[cciccone]

Can I use game theory to determine if a defendant should go to trial or plead? If he goes to trial and is guilty, maximum sentence, say one year. Not guilty, he walks. If he pleads, he gets 6 months. There doesn't appear to be a fourth option.

[Gametheory]

@Talusjay Good for you for taking interest.

[ChiragVora]

I too thought the same. Thanks for clarification.

[Gametheory]

@cciccone61 Game theory describes strategic interactions between two more players. That example only has one player (the defendant), so you can't model it in the way I do here.

[annakriks]

@SecondStageConsult THANK YOU for mentioning that, I felt that was so confusing