If you have ever gone to lunch with coworkers you probably have experienced the prisoner’s dilemma. How did you split the check? Suppose everyone had agreed to split the check equally. If everyone ordered the same amount of food there is no problem. However, if John orders an appetizer, a dessert, and a bottle of wine, the others are subsidizing John’s lunch. Therefore, almost everyone will order more food. Otherwise, they are paying for John’s lunch. This is an example of the prisoner’s dilemma.
The prisoner’s dilemma and the tragedy of the commons are two metaphors in a larger metaphor called game theory. The concepts go back centuries. David Hume (1711-1776) wrote about a situation where two farmers had a pasture next to a swamp. It would be in the best interest of both farmers to drain the swamp, but one farmer figured he could get all the benefits with none of the work if the other farmer drained the swamp. Each waited for the other to drain the swamp and consequently the swamp never got drained.
The name The Prisoner’s Dilemma comes from the following scenario: Imagine that two partners in crime are arrested and are held in separate rooms. If both suspects keep quiet, there won’t be any evidence to convict them. But if one prisoner rats on the other, the silent prisoner will get a harsher sentence. The prisoner who confesses will go free. If both confess, they both will receive a harsh sentence. What does each prisoner do? It would be in the best interest of both prisoners to keep quiet, but the incentive is powerful for each prisoner to confess since each cannot trust the other to keep quiet.
This classroom game will help students understand how the prisoner's dilemma is a metaphor for much of society's problems.