The Joker's dilemma

In the new Batman film the joker sets up a situation. He tells the citizens of Gotham that anyone in the city at midnight will be at risk of being blown up. He also announces that the roads and bridges out of the city are booby trapped with bombs. The army are called in to deal with the crisis and they start to evacuate people on ships. Two ships are loaded with people and are leaving Gotham city. One has prisoners on board. One has innocent citizens on board. Both ships have a bomb on board. The joker tells the passengers on each ship that they have a choice. Each ship has the detonator for the bomb on the other ship. If they choose to press the button the other ship will be blown up and they will survive. If they don't both ships will be blown up by the joker. They have until midnight to make a decision.

This is a variation of the prisoners dilemma. You can read the basic version of the prisoners dilemma

So, what would you do?

You can play a version of the prisoners dilemma here.

The prisoners dilemma has been used to investigate reciprocal altruism and the
evolution of cooperation. Richard Axelrod developed a computer version of the prisoners dilemma and found that if played enough times being nice and cooperating with the other player emerges as the best long term strategy.

Evolutionary biologists have used this finding to explain how human beings have evolved to work and cooperate with each other. Human beings are social animals and live in groups. In our evolutionary past this provided protection from predators and contributed to survival. But living in groups also brings problems: conflicts over food, conflict over potential mates. Forming social alliances and friendships within the group provided protection from others and promoted the sharing of resources. But there is always the possibility that we will be 'ripped off'. Food, protection, help given may not be returned. This is known as the free rider problem: some people might take advantage of the group and just take and not give. If free riders could not be detected then they would do better than other members of the group, reproduce more and eventually everyone would be a free rider and human beings would no longer be able to live in social groups. We could no longer trust other people to help us when we needed it.

Axelrod found that over time a 'tit for tat' strategy was the most successful strategy when playing the prisoners dilemma. In our evolutionary past we lived in small groups and interacted with the same people day after day. If help was given but later this favour was not returned then the free-rider could eventually be found out and punished. They may ask for help but this request could be ignored. This is one way cooperation could evolve.

The youtube clip below is the first part of a documentary by Richard Dawkins called 'Nice Guys Finish First'.

If you want to watch the rest of the documentary you can see it in a series of linked youtube clips here.

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