Spoilers for The Dark Knight follow.



Game Theory and the Prisoner’s Dilemma:



Two boats are adrift in a harbor. Both boats are rigged with explosives and each boat has the detonator to the other boat’s bombs. These boats are then presented with an ultimatum: if one boat uses the other boat’s detonator, then the boat left standing gets to stay afloat unharmed but if neither boat acts against the other by a certain time, then both boats will be blown up.

This scenario is precisely what is presented in the climax of the 2008 Christopher Nolan film. It is also recognizable as a variation of the Prisoner’s Dilemma, a thought experiment used in Game Theory to explain, predict, or demonstrate human behavior in controlled conditions. Rather than bore the internet with another erroneous assertion that Joker is an Anarchist, I will instead highlight the methods he goes through in an attempt to prove his philosophies, what those methods prove (or do not prove), and what conclusions I believe the film wants us to draw from these amoral tests.

The Prisoner’s Dilemma is a scenario in which two independent agents have the option to betray one another for selfish gain. The original Prisoner’s Dilemma features a positive outcome if neither agent betrays each other but Joker allows for no such outcome. The choice for the people on his boats is a simple one: kill or be killed. Joker is using this awful game to make a philosophical point “You see, their morals, their “code”, is a bad joke. Dropped at the first sign of trouble. They’re only as good as the world allows them to be. I’ll show you. When the chips are down these “civilized people”, they’ll eat each other.” The point isn’t about anarchy or any other form of government, it’s about human nature.

In The Philosophy of the DCEU Part I, we talked about Thomas Hobbes and his view on human nature. Joker firmly agrees that humans are self-seeking, corrupt, and savage at their very core and sets out on a number of brutal experiments to prove it. I say “experiments” but “games” are a more apt description. Notice how Joker’s language uses phrasing and idioms associated with card gambling “when the chips are down.” His first rival within the mob is a guy called “Gambol”, he presents one of his scenarios to Batman as “my little game”, he calls himself “tonight’s entertainment”, and refers to his machinations with Harvey Dent as his “Ace in the Hole”. Gotham is Joker’s casino and Joker is the house… And the House always wins.

So what of this Prisoner’s Dilemma on the ship? Recall that neither ship can communicate with each other or with the outside world. There is no cooperation between vessels and no knowledge of any possible outside help. The only information they have is who is on the other ship: one is filled with civilians who are so sick of crime in their city that many celebrate a masked vigilante and the others are prisoners who, largely, resent the people walking free who some feel either failed them or put them there. In the typical Prisoner’s Dilemma, the two prisoners are co-conspirators with leverage on one another, if not quite trust. If both prisoners refuse to act against each other, there is a positive outcome. This is not so with our boats. So the scenario is skewed towards a negative result, incentivizing the reinforcement of Joker’s point. In other words, it’s a stacked deck. The conditions favor the house. The results of this game are tainted by the setup, which favors a certain outcome. Even if one of the boats had chosen to destroy the other, Joker’s point is not proved as he only was able to produce the result under extreme duress, not the mere decay of rules. To their credit, despite their being willing individuals on both ships to destroy the other, self-sacrificial individuals on both ships lead by refusal and prevented the catastrophe from occurring. But this final act test is far from Joker’s only game in the film.

Joker Plays Chicken:

“Chicken” is a game with many variations but The Dark Knight shows us a twist on the classic variation. In chicken, two vehicles are hurtling towards one another. If one swerves to avoid the collision, then that person is branded a coward and loses the game. If no one swerves, then the collision will (at least) harm both drivers and it will result in a double loss. The only way to win is if your opponent cowers but you do not.

At the conclusion of one of the most memorable confrontations in, the Joker challenges Batman to a game of chicken where Joker is on foot and Batman is barreling towards Joker on The Bat-Pod. This may seem unfairly advantageous to Batman, but it is perhaps more balanced than one would initially believe. First, the Bat-Pod is a small vehicle and so a collision is likely to hurt Batman as well. Secondly, Joker values his point far more than his safety (even going so far as to goad Batman into hitting him). Finally, this Batman values life more than vengeance.

The results are clear, Batman swerves to avoid Joker and Joker doesn’t flinch. So Joker wins, right? Wrong. What did we say Joker’s viewpoint was? Morality is a joke that is cast aside in service of self-interest. Joker is a murdering sociopath. Batman’s self-interest is in hitting Joker and ending these games. Batman chooses morality over self-interest. Joker inverted the terms of the chicken game so that collision was his only winning result.

The Dictator Game:

There is an economics Game Theory experiment called the Dictator Game in which one person is given a sum of money that he may share with a second player who is not allowed a say in how much he gains from it. The scenario is designed to disprove the notion that people only act in self-interest. It’s mostly a straw man since very few argue that most people act entirely in self-interest and advocates of the belief that humans are largely self-interested would say that people are disproportionately self-interested. That’s another topic. Joker upends this game with his own spin.

Instead of an endowment of money, Joker chooses two human lives: one which is personally important to Batman: Rachel Dawes, and one which is more beneficial to Gotham as a collective: Harvey Dent. Joker is aware that Batman is fast enough to save one but not the other and so he gives Batman and the Police the address to both would-be victims (not before reversing the addresses) and lets Batman choose who lives and who dies. Batman goes for Rachel, choosing to invest the finer percentage of effort (his) in his own self-interest. The House always has the game rigged though, and Batman arrives at the warehouse containing Harvey Dent instead.

The Hospital and the Trolley Game:

When Coleman Reese threatens to reveal the identity of Batman to the media, Joker makes another ultimatum: if Reese isn’t dead in an hour, he’ll blow up a hospital. While this scenario doesn’t exactly fit Game Theory, it is possible to view it as such since Joker puts it to the test. The GCPD has a tough go at defending Reese since many Gothamites with hospitalized family members have ample incentive to kill Reese. This is reminiscent of the ethical quandary known as The Trolley Problem.

The Trolley Problem presents it this way: a Trolley is rolling down a track towards five people tied down to the tracks. There is a lever, however, that if pulled will change the tracks so that it will roll towards one person tied on the track. Do you pull the lever and cause the death of the one or, by your inaction, condemn five? What if one of the five is a family member of yours? Is the negligence on your part murder? Pulling the lever certainly is, as you are the one who condemned the one in that scenario. What is the correct course of action?

Coleman Reese is the one and, unfortunately for him, a lot of people have access to that lever. In the meantime, the GCPD works very hard to clear the hospitals as quickly as possible. Batman and the GCPD are able to escape this scenario by keeping Reese alive long enough for Joker to blow up an evacuated hospital. However, many people did attempt to kill Reese, sort of proving Joker’s point. We’ll call this one a draw.

The Soul of Gotham:

If you’re keeping score, Batman/Gotham are at two with Joker at one with a draw between them. Joker does have, as he says, an Ace in the Hole. He’s able to manipulate and direct Harvey Dent’s grief and righteousness fury into a murderous rampage. In fact, Dent’s decline into Two-Face is sort of a dark mirror to Joker. Joker plays ethical games with his foes but Two-Face leaves it to mere chance, 50-50. In Joker’s twisted casino, Harvey Dent is the sickening roulette wheel. Harvey Dent’s slide into madness evens up the game to an even score. Though they count Dent as a +2 since he is the paragon of Gotham, the White Knight. Joker wanted to prove that human nature was gruesome and that civilization is a sham. In a sense, he’s right but the real answer is not likely as straightforward as it is here. We may never know the full truth of human nature but the ending ofis clear: if civilization is all that keeps the darkness of man in place, if it is a bad joke or a lie, then is it perhaps a lie worth telling?