Last night I went to see the Dark Knight.
For my own interest all through the plotline was scattered references about chance, chaos vs order and psychological gameplay.
The Joker described himself as an agent of chaos and then aided in the turning of Harvey Dent into an ‘agent of chance’. Games were set up where Batman and the police had to make a choice about what to do or where to put their resources at any one time. “Kill this man in 60 minutes or I blow up a hospital” or “She is in one place, he is in another – who are you going to save?”
But the moment in the film that was the most satisfying (both in terms of my game research and also just generally) was the sequence where the two ferry boats have been given detonators to bombs on the opposite ferry. This is a version of a classic game theory problem known as The Prisoner’s Dilemma;
Two suspects are arrested by the police. The police have insufficient evidence for a conviction, and, having separated both prisoners, visit each of them to offer the same deal. If one testifies (“defects”) for the prosecution against the other and the other remains silent, the betrayer goes free and the silent accomplice receives the full 10-year sentence. If both remain silent, both prisoners are sentenced to only six months in jail for a minor charge. If each betrays the other, each receives a five-year sentence. Each prisoner must choose to betray the other or to remain silent. Each one is assured that the other would not know about the betrayal before the end of the investigation. How should the prisoners act?
In this game, regardless of what the opponent chooses, each player always receives a higher payoff (lesser sentence) by betraying; that is to say that betraying is the strictly dominant strategy. For instance, Prisoner A can accurately say, “No matter what Prisoner B does, I personally am better off betraying than staying silent. Therefore, for my own sake, I should betray.” However, if the other player acts similarly, then they both betray and both get a lower payoff than they would get by staying silent. Rational self-interested decisions result in each prisoner’s being worse off than if each chose to lessen the sentence of the accomplice at the cost of staying a little longer in jail himself. Hence a seeming dilemma.
So, the odds are clearly with ‘betrayal’, you are generally better off.
However the amazing thing about this exercise when played for real – the players in this situation will NOT betray the other ‘prisoner’. Why is this? Is it too naive and optimistic to believe that people are good? that they will do the ‘right’ thing?
In the case of the people on the ferries in Dark Knight, they chose not to blow the other people up. The effect of this in the film was to elevate these regular, normal people into the fabric of the storyline. We were no longer watching the Joker and Batman play out some sort of iconic godlike battle above the city, it was no longer about order vs chaos it was purely empathy for another person like oneself.
