Talk:Prisoner's dilemma

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Because...[edit]

"Because betraying a partner offers a greater reward than cooperating with them..."

But in one scenario it also offers a greater downside doesn't it? Might it be better written as:

"Because betraying a partner offers ON AVERAGE a greater reward than cooperating with them..."?

But that still doesn't make sense, as either version suggests that whatever course of action is chosen, it will result in a 'reward'. So maybe something like:

"Because betraying a partner results, on average, in a lighter sentence..."? — Preceding unsigned comment added by 49.49.24.98 (talk) 22:26, 20 March 2014 (UTC)

In both the case where your opponent cooperates and defects, defecting gives a higher personal payoff than cooperating (0 years vs 1 year if they cooperate, 2 years vs 3 years if they defect). No "on average" required. Binkyuk (talk) 09:57, 3 July 2014 (UTC)

"Cooperates" - terminology[edit]

I found the term "cooperates" a little confusing at first, mainly because it is used more commonly as: "the prisoner cooperates with the police" - the exact opposite to the meaning in the article. It is also not a good antonym for "betrays". A better term might be "remains loyal". — Preceding unsigned comment added by 157.189.16.194 (talk) 04:22, 14 February 2012 (UTC)

Exactly what I was thinking. Perhaps "collaborate" is a suitable replacement? It definitely does not have the same police connotation. — Preceding unsigned comment added by 141.166.209.17 (talk) 02:04, 15 December 2012 (UTC)

I agree too. The lead section talks about confessing or denying the crime. The first sub-section talks about cooperating or defecting. It is hard to tell which matches with which. Is "cooperating" cooperating with the police by confessing or is it cooperating with the other and denying the crime? How about clarifying the terminology and making it easier to follow through the article.
And then there is confusion between confessing to the crime, denying the crime, and saying that the other one did it. Bubba73 You talkin' to me? 05:29, 19 October 2013 (UTC)

Snowdrift = Chicken[edit]

Did anyone notice that the snowdrift game on the bottom of the page is also a version of Chicken (game)?

174.67.247.165 (talk) 04:20, 24 January 2013 (UTC)

Different payoffs[edit]

I'm no game theorist by any means but there is something very unsettling about this game and I think it has to do with the way the payoffs are designated for each player. I think this is a better payoff matrix:

Prisoner B stays silent (cooperates) Prisoner B betrays (defects)
Prisoner A stays silent (cooperates) Both go free Prisoner A: 3 years
Prisoner B: 1 year
Prisoner A betrays (defects) Prisoner A: 1 year
Prisoner B: 3 years
Each serves 2 years

In this case, if both players keep quiet they both go free given that the police has no evidence to convict them. If they both confess they both get 2 years (just as in the original matrix). If one of them confesses while the other keeps quiet, the one that betrays should be "rewarded" by getting a lesser sentence (but not go free) and the one that stays silent should be "punished" by getting an extended sentence.

In payouts notation:


Example PD Payouts (A, B)
B cooperates B defects
A cooperates 200, 200 -100, 100
A defects 100, -100 0, 0

What would be the equilibrium in this case? Is this a different game? Maybe I'm a bad guy who just wants the criminals to get away... — Preceding unsigned comment added by 201.171.99.55 (talk) 18:47, 15 September 2013 (UTC)

That would indeed be a different game. Your payoff matrix doesn't conform to the T > R > P > S requirement for it to be a PD, because T < R. Binkyuk (talk) 15:41, 8 January 2014 (UTC)
Yes, and the consequence of T<R is that cooperation is always guaranteed for "rational" players. If both players are trying to maximize their income (or freedom) and both know it, they will always cooperate. PAR (talk) 04:40, 3 July 2014 (UTC)

Something about bats...[edit]

Example of payout in the behavioral exchange of vampire bats who engage in reciprocal feeding of non relatives [1]

C/C: "Reward: I get blood on my unlucky nights, which saves me from starving. I have to give blood on my lucky nights, which doesn't cost me too much."
D/C: "Temptation: You save my life on my poor night. But then I get the added benefit of not having to pay the slight cost of feeding you on my good night."
C/D: "Sucker's Payoff: I pay the cost of saving your life on my good night. But on my bad night you don't feed me and I run a real risk of starving to death."
D/D: "Punishment: I don't have to pay the slight costs of feeding you on my good nights. But I run a real risk of starving on my poor nights."

real life examples[edit]

Shouldn't the real life examples include, you know, the actual scenario on which the original PD is based? like prosecutors/cops and suspects in, eg, the US legal system? — Preceding unsigned comment added by 68.65.169.68 (talk) 01:14, 6 April 2014 (UTC)

In real world, there is probability the criminal gang would retaliate against the betrayer who was set free at partner's expense.

First, no one expects the real world example to fit the model perfectly; it's an approximation. Second, this deviation from the model you mention isnt essential to the OP's scenario (it might not be gang-related, witness protection etc). Third, the retaliation might not offset the incrementally better sentence from snitching. I think the OP has a point. "Prisoner's dilemma" doesn't seem like one of those labels that's a complete misnomer; it could turn up in cases of actual prisoners in a given legal system. Snarfblaat (talk) 00:32, 5 November 2014 (UTC)
    • ^ Dawkins, Richard (2006). The selfish gene. Oxford university press.