The prisoners’ dilemma fascinates social scientists because it is an interaction where the individual pursuit of what seems rational produces a collectively self-defeating result. Each person does what appears best to them and yet the outcome is painfully inferior for all. Even though there is nothing obviously faulty with their logic, their attempt to improve their prospects makes everyone worse off. The paradoxical quality of this result helps explain part of the fascination. But the major reason for the interest is purely practical. Outcomes in social life are often less than we might hope and the prisoners’ dilemma provides one possible key to their understanding.
The name comes from a particular illustration of the interaction which is credited to Albert Tucker in the 1950s. In this example, two people are picked up by the police for a robbery and placed in separate cells. They both have the option to confess to the crime or not, and the district attorney tells each of them what is likely to happen and makes each an offer. Figure 5.1 sets out the likely consequences presented by the district attorney in terms of years in prison.
The rationale behind these (negative) pay-offs is something like this. If both ‘confess’ then the judge, being in no doubt over their guilt, will give them 3 years each in prison. Whereas if they both ‘don’t confess’ then