Breaking Out of the Prisoner’s Dilemma

An interesting piece from Wired Science on a new article concerning the evolution of cooperation among self-interested individuals. The article focuses on the Prisoner’s Dilemma, that old chestnut of game theory, described in this way in the Stanford Encyclopedia of Philosophy:

Tanya and Cinque have been arrested for robbing the Hibernia Savings Bank and placed in separate isolation cells. Both care much more about their personal freedom than about the welfare of their accomplice. A clever prosecutor makes the following offer to each. “You may choose to confess or remain silent. If you confess and your accomplice remains silent I will drop all charges against you and use your testimony to ensure that your accomplice does serious time. Likewise, if your accomplice confesses while you remain silent, they will go free while you do the time. If you both confess I get two convictions, but I’ll see to it that you both get early parole. If you both remain silent, I’ll have to settle for token sentences on firearms possession charges. If you wish to confess, you must leave a note with the jailer before my return tomorrow morning.”

The “dilemma” faced by the prisoners here is that, whatever the other does, each is better off confessing than remaining silent. But the outcome obtained when both confess is worse for each than the outcome they would have obtained had both remained silent.

Game theory (and the prisoner’s dilemma, in partiuclar) have been used by Eric Posner and Jack Goldsmith to critique the efficacy of international law and, conversely, by Andrew Guzman (and others) to explain how international law works (the title of Guzman’s book).  The new research, by Swiss Federal Institute of Technology sociologists Dirk Helbing and Wenjian Yu, focuses not on a single game, but what happens when there are multiple two-player games, but a large crowd of players. They write: “We report the sudden outbreak of predominant cooperation in a noisy world dominated by selfishness and defection.” Here is the crux of Wired’s take on the research (and check out the full piece at the Wired Science blog, which includes an graphical simulation.):

The key, suggests Helbing’s simulation, is mobility and imitation. When individuals are free to choose their associates and smart enough to imitate their success, cooperation emerges, then flourishes — and it doesn’t take much to start the process. At each iteration in the simulation, just one in 20 units had a chance of abandoning selfishness, and the choice was usually punished.

“After a very long time, there will be two or three or four individuals in the same neighborhood who just happen to cooperate, just by chance,” said Helbing. “It’s a happy coincidence — and once there’s a sufficiently large cluster, cooperators do quite well. Defectors start to copy the behavior of cooperative clusters. And cooperation can persist and spread.”

In many ways, the Prisoner’s Dilemma simulation is for game theorists what fruit flies are to biologists: a simple system in which basic principles can be uncovered, examined and hopefully extrapolated to people. It’s just a model; a bit of mobility and imitation won’t magically fix humanity’s problems. But they might be important.

I’ll let Posner et al. slug it out over whether or not this means customary international law is reallylaw or “just” cooperation, etc. For me, the interesting thing about this result are the implications for how we can construct legal regimes (another theme of Guzman’s scholarship).  Helbing and Yu focus on the importance of moving people around in order to set the preconditions for cooperation. I wonder if it is literally that, or if the key aspect (for them) was the importance of moving information around–that is letting other players know about successful strategies, thus giving them the incentive to imitate those strategies in an attempt to get similar results. If that is the case, then this may reinforce the arguments (particularly of  insitutionalist and constructivist scholars) that we need to go beyond arguments over enforcement mechanisms in international law and pay more attention to information dispersal and socialization.