To defeat corruption, we need to understand why it arises in the first place. For that, we need game theory. A ‘game’ is a stylised scenario in which each player receives a pay‑off determined by the strategies chosen by all players. There’s also a variant of game theory that deals with so-called evolutionary games. In that kind of scenario, we imagine a population of self-reproducing strategies that get to multiply depending on the pay‑offs they achieve. A strategy is said to be ‘evolutionarily stable’ if, once it is widely adopted, no rival can spread by natural selection.
The archetypal co‑operation game is the Prisoner’s Dilemma. Imagine that two prisoners, each held in isolation, are given a chance to rat on the other. If only one takes the bait, he gets a reduced prison sentence while the other gets a longer one. But if both take it, neither gets a reduction. In other words, mutual co‑operation (saying nothing) provides a higher reward than mutual defection (ratting on your partner), but the best reward comes from defecting while your partner tries to co‑operate with you, while the lowest pay‑off comes from trying to co‑operate with your partner while he stabs you in the back.
The most obvious evolutionarily stable strategy in this game is simple: always defect. If your partner co‑operates, you exploit his naïveté, and if he defects, you will still do better than if you had co‑operated. So there is no possible strategy that can defeat the principle ‘always act like an untrusting jerk’.
At this point, you could be forgiven for thinking that game theory is both appalling and ridiculous. Co‑operation clearly pays off. Indeed, if you make normal people (ie people who are not economics students) play the Prisoner’s Dilemma, they almost never defect. And not just people. Rats will go out of their way to free a trapped cage-mate; rhesus monkeys will starve for days rather than shock a companion. Even bacteria are capable of supreme acts of altruism.
This trend toward biological niceness has been something of an embarrassment for biology. In fact, the task of finding ways around the more dismal conclusions of game theory has become a sub-disciplinary cottage industry. In the Prisoner’s Dilemma, for example, it turns out that when players are allowed to form relationships, co‑operators can beat defectors simply by avoiding them. That’s fine in small societies, but it leaves us with the problem of co‑operation in large groups, where interactions among strangers are inevitable.
Game theory (as well as common sense) tells us that policing can help. Just grant some individuals the power and inclination to punish defectors and the attractions of cheating immediately look less compelling. This is a good first pass at a solution: not for nothing do we find police-like entities among ants, bees, wasps, and within our own bodies. But that just leads us back to the problem of corruption. What happens if the police themselves become criminals, using their unusual powers for private profit? Who watches the watchers?
In 2010, two researchers at the University of Tennessee built a game-theoretical model to examine just this problem. The results, published by Francisco Úbeda and Edgar Duéñez-Guzmán in a paper called ‘Power and Corruption’, were, frankly, depressing. Nothing, they concluded, would stop corruption from dominating an evolving police system. Once it arose, it would remain stable under almost any circumstances. The only silver lining was that the bad police could still suppress defection in the rest of society. The result was a mixed population of gullible sheep and hypocritical overlords. Net wellbeing does end up somewhat higher than it would be if everyone acted entirely selfishly, but all in all you end up with a society rather like that of the tree wasps.