The Prisoner’s Dilemma


Let’s say Mr. Blue, and Ms. Red have each
been arrested for some minor crime. The police think they committed a more serious crime
but they don’t have enough evidence to convict them. They need a confession. They take them
and put them in separate rooms so they can’t talk, and play a little game.
To try to force a confession the police give them each a choice. Admit your partner committed
the crime, and you will go free. We’ll pardon you for the minor crime but your partner will
have to spend 3 years in prison. If you stay silent and your partner lets us know that
you were the one who really did it then you’re going to have to go away for 3 years.
They know that the police don’t have any evidence and if they both stay silent then they will
only go to prison for 1 year each for the minor crime. If they both betray each other
then they’ll both go to prison for 2 years each.
OK, each partner can do 1 of 2 things. Stay Silent, or Betray. Staying silent would be
cooperating and betraying would be defecting. If they both stay silent, they each spend
a year in prison. If one betrays and the other stays silent, then the betrayer goes free
and the silent spends 3 years in prison. If they both betray then it’s 2 years each. So
what are they going to do? Well they should cooperate. That’s the best option for the
group, if we add the total number of years in prison.
But let’s take it from Red’s perspective. If she thinks blue is going to stay silent,
then she should betray so she can go free. Going free is better than a year in prison.
If she thinks he’s going to betray her then she should definitely betray, 2 years in jail
is better than 3 and being made a fool of. Blue is in the exact same situation and will
think the exact same thing, he should betray if she stays silent and he should betray if
she betrays. They should have both cooperated, but from
an individual stand point they noticed they could always gain by defecting. If they have
no control over what the other person is going to do. So they’ll both defect to try to better
their own situation. But come away not only hurting the group, but themselves. Individually
they’re worse off than if they both cooperated. This situation is pretty made up, but it has
some real world analogues. A common example is with marketing .
Let’s say 2 cigarette companies, Red Strikes, and Smooth blue, are deciding how much money
they should spend on advertising. Since the product they each make is identical to one
another, advertising has a huge impact on sales. For simplicity let’s say their choices
are: to advertise a bunch, or not advertise at all. And there’s just 100 people in this
society and they all smoke. If both don’t advertise, then just by random chance picking
cigarette boxes, 50 people buy Red Strikes and 50 people buy Smooth blue. At $2 a pack
they each make $100. Let’s say advertising costs $30. If one person advertises and the
other does not, then 80 people will buy the cigarettes from the ads and 20 people buy
the other ones. The advertiser makes $160 minus $30 for ads, and comes away with $130.
The non advertiser didn’t spend money, but only made $40. If they both advertise, again
half will buy Red Strikes, and half will buy Smooth blue. But since they both spent $30
on advertising, they only come away with only $70 each.
Same deal, both people cooperating and not advertising is the most preferable situation,
but both company can see that advertising will always make them more money.
But unlike the prisoner’s in jail, these companies can talk and try to influence each other.
From here Blue would be better off if Red didn’t advertise. Red wouldn’t go for that
because that would be worse for them. Blue could try to convince Red that they would
both not advertise, the only other situation where they’re both better off. But without
any real obligation to each other, there’s nothing that’s stopping them from trying to
advertise to gain more of the market anyway. If you think your opponent’s going to not
advertise, you’re better off advertising. Although we’re still making assumptions to
make this situation work too. With this model we’re assuming they only play once. The game
changes when the players have a chance to build a relationship and work together to
get more gains over time, or punish each other by not cooperating.
Also to make the model work we have to make up rules for the players. Assume they’re basically
computer programs with predictable actions. These guys are creepier than they were in
my head. They were supposed to be cute. For the prisoner’s dilemma and other similar
models, we’re assuming they are Rational Agents. A rational agent is a hypothetical person
that will always pick the option that they predict will work out best for them. They’re
not really thinking about the gains of someone else. Seems selfish but it something that
real people will generally do too. People always want what’s best for themselves and
we don’t like to made a fool of. But if you put real people in the prisoner’s
dilemma, people don’t always defect like the model predicts.
In one study, 40 people playing prisoner’s dilemma games, through a computer, without
ever meeting or talking, only playing each opponent once, these are one off games, using
a payoff matrix that looks like this, cooperated an averaged 22% of the time. These people
never cooperated. These are people always cooperated. These guys cooperated on half
of their games and everyone else is in between. This is a lot of cooperation coming from a
model that predicts no cooperation. The largest group did act like rational agents,
but most people tried to cooperate at least once.
It’s because there’s more to real people. We are social creatures and even in a one
off scenario with no guarantees and obligations and no chance to build a relationship, we’re
still thinking about how the group might decide. We’re actually thinking from the perspective
of the group, and making an optimistic decision. Cooperating an average of 20% of the time
might not seem very optimistic, but remember this is with absolutely no communication or
obligations. Anyways, that’s not really the point. Using
the rational agent is still useful. The model is just trying to point out the dilemma of
certain specific situation where people actually hurting themselves when counter-intuitively,
they’re only thinking about themselves… and that’s why we’re modelling using the cold
robotic sociopaths.

100 thoughts on “The Prisoner’s Dilemma

  1. Use tit for tat. He explained that the two companies can’t trust each other to not cheat them. A study of the prisoner’s dilemma over multiple iterations with many strategies found that the best strategy for both sides to be rewarded is called tit for tat. The default action is cooperation. If the other side fails to cooperate, you punish them by not cooperating the next round. This incentivizes the other side to cooperate.

  2. What if you admit to the crime? You just get imprisoned and the other guy goes free? Or do these police people have a little sympathy?

  3. This is quite a selfish model.. There is an option that my moral qualities tells me to not hurt the other person even tough the other person might hurt me.

  4. EZ just talk about this dilemma to your crime partner before the crime and agree to say one thing when caught

  5. That's partly why the evolution of currencies and values is a little difficult to predict. We can model their variations but this model will always be incomplete due to the strong non-linearity and unpredictability of human behaviour

  6. Red and blue would never betray each other they are to smart for that!
    Tell me if anyone understands the overly sarcastic productions reference.

  7. see this in action. Search youtube for golden balls the weirdest split or steal ever. It shows a game show that uses this idea but lets the contestants discuss before secretly choosing to split or steal game winnings.

  8. me: aw shit my favorite tv show drama thats sponsored by red strikes and smooth blue is about to start

    0:03 previously on THE NO NECKS

  9. Ari Spyros: It's what I like to call the prisoner's dilemma.
    Chuck Rhoades: No, you don't like to call it that. That's what it's called.

  10. "gEt a LaWyEr" ok fuck off, economists are trying to study! This is game of theory model not just a random video of how should you behave if you get in prison

  11. I think this nicely highlights how irrational and illogical humans are, and how poorly we understand statistics without training, and how we ultimately are secretly always trying to gain advantage over others. We justify it by saying we just don't want the other person to get more than us. We try to make it fair, but in doing so, we inadvertently make it unfair.

  12. How about if you both cooperate you both get 1 year
    If you defect and the other doesn't you get a year minus a day and the other gets 80 years
    Vise versa
    If you both defect then both of you will get 100 years….

    You can see where I'm getting at right?
    It's also the conditions that surrounds the deals…..

  13. But, if the police needed a confession due to the fact that there is NO evidence between them, couldn't they just ask for a lawyer so the lawyer could share in court that there is no evidence that his defendants committed the crimes they were accused of. Doing this will let them both walk scott free, or at least let them do less than 1 year for the petty crime.

    And yes I know the true message behind this video is "cooperation is key, but humans are too selfish to see that" but the message doesn't go through entirely if you base it around law. The law is a game and there are a shit ton more options than just cooperate or back stab

  14. There was a game show where the winning team had to do a trust or betray thing at the end and if they both trustes, they split the money off one trusted and one betrayed the betrayal got the money but if they both betrayed, nobody got the money

  15. Not trie about marketinng. Business is like an ocran. You can spend on ads to increase brand awareness, get new cusiemers (another 100 from around the world) introduce new products, ad for fun or to attract employees, partners. And without ads, noone will ever know you exist. And only limited stuff is known as ciggies and people buy at counters but noone picks random brands. Guess why marlboro was always the king?

  16. 1:04 You can't sum the numbers because that 1 is the same period of time for both. So, in total it would be just 1.

  17. One problem with this; why would the time have to be split between them like that? The numbers are not adding up.

    We have three years (assuming there is only three years that can be split between the two) of punishment to dole out.
    If one "defects" the other gets 3 years.
    If neither defects, they both get time.
    If they both defect, they still both get time.
    So if one defects, all of the time is given to the other.
    If neither defects, they both get half the time.
    If both defect, they both get half the time.

  18. The real answer is you should shut the fuck up, refuse to speak to police, and wait for your lawyer to arrive regardless of whether you're completely innocent or guilty as all hell.

  19. I get that this happened before but as someone who’s just watched this, it reminds me of the Kakegurui XX tax game

  20. I remember doing this in my class once. If everyone raises their hand, everyone gets 1 candy, if no one raises, everyone gets 2, if 1 raises, he gets 10 and no one else gets anything, if more than one raises, no one gets anything. It was a fun day. We were all betrayed.

  21. 3:39 Theory: All of the options do with working together because the red fist are PewDiePie brofists but you’re colorblind

  22. In real life:

    1) commit crimes alone
    2) Never confess

    In this dilemma with these constraints

    1) always defect- you either yet 0 years or 2 years. No matter what you won’t get 3 years and you might get none

  23. This reminds me of an episode I believe was called prisoners dilemma on a show called white collar. The good guys managed to make the bad guys think that the other was betraying them

  24. ok but wtf are those cigarettes?

    "start early"
    "made for a woman"

    ah, yes
    children smoking and sexism

  25. I knew what I meant due to Zero escape, but your video really helped my explaining it to others.

    My thanks, dear friend past the wild, blue waves.

  26. Trick question, whoever is leading the enterrogation goes to jail for lack of information, expulsion, and premature imprisonment. They also revoked several rights in the constitution and never gave them a trial in court.

  27. Always defect, if the other stays loyal, you get off, if they defect, you get small revenge. There's a 1/2 chance they defect if both of their choices are equal. So 1 year if they stay and a 3 year if they defect. If you take the average results of you staying loyal it's still 2 years. In conclusion, if you defect you can only get the average jail time for staying loyal or better. Betrayal is the better choice. If the time for the more serious crime was worse, then it would be better to stay loyal. At least, that's what I think.

  28. I’d rat my other partner out no matter what because if they stay silent I get off Scott free and if they rat me out too it’s only 2 years

  29. Their are a number of issues with this idea.

    For 1 if their is no evidence than they wouldn't get even a single year in prision.

    2nd Lawyers exsit

    3rd Loyalty is actually a thing, and people will often not give people up for that reason. Which is more or less how organized crime works.

  30. The prisoner's dilemma also applies to Tragedy of The Commons type problems (e.g. countries deciding whether to cooperate to stop climate change, fishing companies deciding whether to limit their fishing to leave enough fish in the sea to repopulate, etc). What is in everyone's collective interest may not be the most rational choice from the individual's perspective.

  31. i just came from an clip from Golden balls (stop laughing) that very closes mirror the prisoners dilemma.

    https://www.youtube.com/watch?v=p3Uos2fzIJ0

  32. Assuming it's a computer program instead of a person, or people who know each other to be great strategists, wouldn't both reach the conclusion that cooperation is better overall if both cooperate, leading to both cooperating, knowing that the other would also cooperate to reach the best possible outcome?

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