The world of game theory is currently on fire. In May, Freeman Dyson at Princeton University and William Press at the University of Texas announced that they had discovered a previously unknown strategy for the game of prisoner’s dilemma which guarantees one player a better outcome than the other.
That’s a monumental surprise. Theorists have studied Prisoner’s Dilemma for decades, using it as a model for the emergence of co-operation in nature. This work has had a profound impact on disciplines such as economics, evolutionary biology and, of course, game theory itself. The new result will have impact in all these areas and more.
Until now, everyone thought the best strategy in iterative prisoner’s dilemma was to copy your opponents behaviour in the previous round. This tit-for-tat approach guarantees that you both spend the same time in jail [i.e. neither participant was better (or worse) off].
That conclusion was based on decades of computer simulations and a certain blind faith in the symmetry of the solution.
So the news that there are other strategies that allow one player to not only beat the other but to determine their time in jail is nothing short of revolutionary.
Press and Dyson’s discovery has sent game theorists scurrying to work out the implications. They’ve been using prisoner’s dilemma to gain insight into everything from Cold War politics and climate change negotiations to psychology and, of course, the evolutionary origin of co-operation itself.