Sunday, March 26, 2006

Prisoner's dilemma

Sorry about the stagnatation.Here's the Prisoner's dilemma as I've promised. This is mentioned in a chapter in Matt Ridley's "The Origins of Virtue: Human instincts and the Evolution of Cooperation" It is actually a game, the most famous game in all of game theory which has been central to one of the most exciting scientific discoveries of recent years - nothing less than an understanding of why people are nice to each other. It applies whenever there is a conflict between self-interest and the common good. The game is called the prisoner's dilemma because the commonest anecdote to illustrate it describes two prisoners each faced with the choise of giving evidence against the other and so reducing his own sentence. The dilemma arises because if neither defects on the other, the polive can convict them both only on a lesser charge, so both would be better off if they stayed silent, but each is individually better off it he defects.

There is another sophisticated version of it known as the stag hunt and a modern version of the stag hunt - the wolf's dilemma. In the wolf's dillema: "Twenty people sit, each in a cubicle, with their fingers on buttons. Each person will get $1,000 after ten minutes, unless someone pushes his button, in which case the person who pushed the button will get $100 and everybody else will get nothing. If you are clever you do not push the button and collect $1000 but if you are very clever, you see that there is a tiny chance that somebody will be stupid enough to push his or her button, in which case you are better off pushing yours first, and if you are very, very clever you see that the very clever people will deduce this and will push their buttons, so you, too, had better push yours. As in the prisoner's dilemma, true logic leads you into collective disaster"

There are many other versions, explanations and etc. elaborated in the chapter. But on reading and understanding the prisoner's and wolf's dilemma alone, it seems quite true when illustrating humans co-operation with each other. For example, in the wolf' dilemma, if everyone collaborated at the start to not push the button together, there is still somehow a normal natural instinct in them that one of them will push the button and all will end up with nth except the person who pushed the button..it is probably a human nature in all of us to think like so.

In the later part of the the chaper, there is actually another game called tit-for-tat which is predicted to be a mechanism for generating co-operation between unrelated individuals. It has got something to do with reciprocity in society. But it is a little too long to elaborate. Anyway, all this is definitely something worth thinking about.

[Acknowledgement: Ridley, Matt.1996.The Origins of Virtue: Human Instincts and the Evolution of Co-operation. 3:53-55, 63.]