Eli5: Why is Prisoners Dilemma considered a Dilemma?
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If we define dilemma as “a situation that requires a choice between options with expected probabilistic payoffs that are or seem equally unfavorable or unsatisfactory”, then dilemma seems appropriate if the prisoners have relationships (for example, familial or other ties) that would lead them to weigh sacrificing their individual interests for the communal interests.
In the usually presented prisoner’s dilemma payoff matrix, I suppose OP is right in that the Nash equilibrium shows that the prisoners don’t truly have a dilemma, with each prisoner having a dominant strategy and each prisoner’s dominant strategy dooming them both.
An ethical dilemma, which is the “genre,” or type, of problem presented is “a situation in which a difficult choice has to be made between two courses of action, either of which entails transgressing a moral principle.” That’s where the “di” of “dilemma” comes from; there are two possible choices.
In the case of the prisoner’s dilemma each person has the choice to stay silent or testify.
A dilemma is a choice between two options. Each of the prisoners can either defect and talk to the police, or they can choose to cooperate and not say anything
I think this post is solved! Thanks for everyone who commented on this. And thanks for all the help offered
The short answer is because the Nash equilibrium is not the same as the pareto optimal solution. But that requires some knowledge of these terms, so let’s talk about what they mean:
“Nash equilibrium” means a point at which both players would agree not to change their move, even knowing the other player’s move. Imagine you and your opponent are discussing what you will do with each other out loud.
“If you pick scissors, I’ll pick rock.” -> “If you pick rock, I’ll pick paper.”
Games like rock paper scissors have ***no*** Nash equilibrium because you would continue changing your move forever and never settle on one.
In Prisoner’s Dilemma, the Nash equilibrium is for both players to defect. If someone stays silent, their opponent benefits more by defecting. If someone defects, their opponent ALSO benefits more by defecting. It’s never advantageous for a player to choose to stay silent, so you can confidently defect knowing it will give you the better outcome.
“Pareto optimal” means you add how good the outcome is for all of the players and treat them as the outcome for a single player, then pick the best outcome. Because both players serve a heavier prison sentence if they both defect, but a lighter prison sentence if they both stay silent, both players staying silent ends up being the pareto optimal solution because it’s all around better for everyone.
The dilemma is that even though both players know the outcome will be better for both of them if they both stay silent, both are directly incentivized to defect. Even if both players understand the game perfectly and are perfectly logical, they will still collectively select an outcome that is worse for both of them.
Keep in mind this only applies when the game is only played once and there is no way to enforce additional consequences on the players. The entire basis of society is built upon removing anonymity and enforcing accountability so that the prisoner’s dilemma never actually occurs in the first place.
it’s a dilemma because you have a difficult decision to make with pros and cons on either side of the choice
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