March 30, Y2k-1

It was about this time, some years ago when I was back in school, when one of my housemates had a dilemma.

A Prisoner's Dilemma, to be more specific.

And since I had taken evolutionary biology, I understood her problem.


The Prisoner's Dilemma

The prisoner's dilemma was originally formulated by mathematician Albert W. Tucker and has since become the classic example of a "non-zero sum" game in economics, political science, evolutionary biology, and of course game theory.

A "zero sum" game is simply a win-lose game such as tic-tac-toe. For every winner, there's a loser. If I win, you lose. Non-zero sum games allow for cooperation. There are moves that benefit both players, and this is what makes these games interesting.

In the prisoner's dilemma, you and Albert are picked up by the police and interrogated in separate cells without a chance to communicate with each other. For the purpose of this game, it makes no difference whether or not you or Albert actually committed the crime. You are both told the same thing:

     If you both confess, you will both get four years in prison. If neither or you confesses, the police will be able to pin part of the crime on you, and you'll both get two years. If one of you confesses but the other doesn't, the confessor will make a deal with the police and will go free while the other one goes to jail for five years.

At first glance the correct strategy appears obvious. No matter what Albert does, you'll be better off "defecting" (confessing). Maddeningly, Albert realizes this as well, so you both end up getting four years. Ironically, if you had both "cooperated" (refused to confess), you would both be much better off.


My housemate was taking a psychology course and her professor had instructed the class to come up with another real life example of the Prisoner's Dilemma. My housemate was hoping to use the professor as a reference and didn't want to disappoint. So we both tried to come up with examples.

It was hard. The obvious ones, like a nuclear standoff, had already been mentioned in class. We had thought along prisoner's dilemma story lines involving pregnancy, abortion and marriage, but couldn't stomach it and promptly stopped. It's been a while so I can't remember all the other dead ends but I suppose they would have been along the lines of insurance fraud, exam cheating and the like.

I am writing this piece to give public notice of the elegant solution that I eventually found. My housemate was already in a prisoner's dilemma, of sorts.

A. If she doesn't try to come up with an example and she is not chosen by her professor to give an example, she is spared a good hour of homework - an hour that can be used to watch Beverly Hills 90210 - without any repercussions to the esteem held by her professor.

B. If she doesn't come up with an example, watches Bev instead, but is chosen by her professor, then the hour of TV bliss is offset by the bad reviews she will get by her professor in future grad school applications.

C. If she does take the time to make up an example and misses and entire evening of TV and is not called upon by her professor, then she loses an evening of bad TV.

D. If she does come up with an example and the next day in class is called upon to give it, then the evening of lost TV is made up by the fact that the professor will summarily write glowing reviews and she will be able to enter the grad school of her choice.

Incidentally, scenario C played out. Of course.