Christianity and the Prisoner’s Dilemma
Tags: Morality, Economics, Cooperation, Christianity, Prisoners Dilemma

Today in Sunday school we were talking about the Sermon on the Mount and something occurred to me about the importance of this particular sermon in human history. Particularly this part:

“resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also”

One of the reasons this interests me is that as an economic strategy, it just doesn’t work (at first glance). I have previously linked to this website that shows how successful different cooperation strategies are in the context of an iterated prisoner’s dilemma game.

The advice to “turn the other cheek” can be viewed as equivalent to the always cooperate strategy in a prisoners dilemma game. It’s probably pretty obvious to anyone who thinks about it that if some players are always cooperating they are going to get taken advantage of, and won’t survive long.

One way to resolve this problem is to just say that the Sermon on the Mount is a spiritual strategy and it has nothing to do with economic games. But I don’t think so. I think Christianity represents a moral transition from one way of resolving the prisoner’s dilemma to another, more efficient way that has become the basis for the modern world.

Specifically, the old strategy can be represented as something like the tit-for-tat prisoners dilemma strategy. Basically, it is the morality of the personal vendetta. If someone does you wrong, you are justified in punishing that person.

However, the personal vendetta morality has its limitations. It can lead to a long series of non-cooperative behavior that ultimately hurts everyone involved (i.e., a feud). But even long feuds seem preferable to just letting the wolves devour all the sheep….doesn’t it? That’s kind of what the game simulations tell us.

Still, in Christian morality, every individual has a responsibility to repeatedly cooperate with their neighbor. If someone takes your coat, let him have your cloak, too. So what is going to prevent everyone from adopting predatory strategies to take advantage of all this cooperation? A higher authority. In the Sermon on the Mount, Christ explicitly refers to God as that higher authority:

“thy Father which seeth in secret himself shall reward thee openly”

So Christianity represents a transition from personal vendetta morality to something more efficient, namely, the let-a-higher-authority-take-care-of-justice theory of morality. You can escape the Prisoner’s Dilemma entirely if you have a third party authority that has the ability to enforce cooperation.

Obviously, most modern societies don’t rely on God to enforce the law. But the basic idea that we have moral responsibility to uber-cooperative and that some higher authority will take care of justice is a moral theory that is much more compatible with modern concepts of justice than the tit-for-tat model.

In fact, there is evidence that societies that adopted Christianity have been more economically successful than others. Max Webber famously attributed this to “work ethic”. However, more recent scholarship has found that a more important difference between societies isn’t how hard they work, but how they cooperate. That is, something like the always cooperate strategy is more conducive to trusting strangers, and engaging in mutually beneficial trade. In other words, the moral theory advanced on the Sermon on the Mount lays the fundamental groundwork for capitalism and the rule of law.