Why So Serious? When Game Theory Can Be Fun!

“There’s only minutes left, so you have to play my game if you wanna save one of them.”

Sounds familiar? You may remember this line from The Dark Knight, the follow-up movie to 2005’s Batman Begins which features a posthumous Oscar-winning performance by the late Heath Ledger. However, the film is much more than meets the eye. The second installment in Christopher Nolan’s Batman trilogy explores further about the villainous side of mankind, as well as themes such as the social order and the consequences of one’s actions. Speaking of one’s actions, some of its characters’ decision making can be rationalized using a familiar theory in economics. This theory comes in mind when watching one of the movie’s many intriguing scenes, including the ferry scene.

Source: Giphy

The ferry scene starts off when Commissioner Gordon (Gary Oldman) discusses about the movement of Gotham City’s criminals who were put away behind bars by the district attorney, Harvey Dent (Aaron Eckhart). He suggests that these prisoners are “moved” via ferries to avoid any possible interruption that might occur in light of the Joker’s (Heath Ledger) ongoing reign of terror. At the same time of the prisoner movement, a commercial ferry is also departing from Gotham City’s harbor. Joker sees this as an opportunity for him to conduct a social experiment. The experiment involves a detonator that can blow up the other ship and a strict ban on escaping the ferry due to the Joker’s possession of a third detonator that can blow up both ships. Given his rule, the detonator seems to play a crucial part in determining the passengers’ strategies. How would they decide what to do with their lives on the line? Game theory of course!





The Joker’s social experiment involves 2 players, ferry A and ferry B, that can either cooperate or detonate the bomb. If only 1 ferry detonates the bomb, then that ferry will survive while the other gets blown up. If both ferries choose to detonate the bomb, then they’ll both end up getting blown up. If both ferries choose to cooperate, then both will end up getting blown up too. However, this strategy is slightly better for the players involved because it shows that neither is willing to kill the other, even though both ferries will eventually get blown up by the Joker.

If we analyze the payoffs, we can see that the players are being put in a situation that resembles a prisoner’s dilemma. No matter what ferry B does, it’s clearly better for ferry A to detonate the bomb. Similarly, no matter what ferry A does, it’s clearly better for ferry B to detonate the bomb. This is the outcome that the Joker thinks is the best since both players would value survival more than morality.

As we see in the movie, both players eventually choose not to detonate the bomb and cooperate, despite not being able to know what the other player is trying to do. This action shows that the value of morality trumps the value of survival and that the Joker miscalculated his game. The prisoner’s dilemma, therefore, cannot work in the Joker’s favor. Furthermore, there’s the addition of Batman’s (Christian Bale) intervention that could change the game completely. So, how do you think Batman factors into the equation? To know the answer and see how it unfolds on screen, well, you just have to watch the movie for a second viewing then.

Disclaimer: This is an old article I wrote back in 2017 which appears in the magazine ‘Warta IE’ for its 2017 issue. To access the full softcopy of the magazine, click here.


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