I am afraid that I do not find the prisoner's dilemma to make ethics interesting. In fact, I seldom find its relevance to ethics.I spoke somewhat loosely in my earlier post. To be more precise, game theory in general is what makes ethics interesting, specifically those elements of game theory where Pareto optima and Nash Equilibria conflict or are undefined or ambiguous. The Prisoner's Dilemma is the best known of these sorts of games, and we can generalize the analysis of the Prisoner's Dilemma to related games, such as the Stag Hunt).
I'm not, of course, the only person interested in the connection between ethics and game theory. From the Wikipedia article:
While it is sometimes thought that morality must involve the constraint of self-interest, David Gauthier famously argues that co-operating in the prisoners dilemma on moral principles is consistent with self-interest and the axioms of game theory. It is most prudent to give up straightforward maximizing and instead adopt a disposition of constrained maximization, according to which one resolves to cooperate with all similarly disposed persons and defect on the rest. In other words, moral constraints are justified because they make us all better off, in terms of our preferences (whatever they may be). This form of contractarianism claims that good moral thinking is just an elevated and subtly strategic version of plain old means-end reasoning. Those that defect can be predicted because people are not completely opaque.I find myself in almost complete agreement with this point of view.
Douglas Hofstadter expresses a strong personal belief that the mathematical symmetry is reinforced by a moral symmetry, along the lines of the Kantian categorical imperative: defecting in the hope that the other player cooperates is morally indefensible. If players treat each other as they would treat themselves, then off-diagonal results cannot occur.
Game theory takes the magic out of ethics. Instead of talking about some mysterious, mystical ethical realism, a game-theoretic ethics makes ethics about something physical — or at least no more unphysical than consciousness in general. Ethics is about the mind directly, about our subjective preferences and desires and about the complex emergent properties of the subjective preferences interacting in a society. Even better, games such as the Prisoner's Dilemma show us that a game-theoretic understanding is not an over-simplification of our ethical intuitions.
Alonzo complains that the Prisoner's Dilemma is "contrived".
It is a highly contrived situation that some skillful interrogators may put into practice to extract confessions from the accused [I'm curious if Alonzo actually read the Wikipedia article], but it does not describe a real-world situation.But it is not so much contrived as it is stripped to its essence. In a very simple game, which can be described precisely in just a few sentences, we find profound emergent properties that force us to reconsider our notions of rationality itself. Any philosopher interested in something other than bloviation and obfuscation should, I think, admire the simplicity, clarity and depth of the Prisoner's Dilemma.