The Prisoner's Dilemma

Contractarianism and The Prisoner’s Dilemma

In the 1950s mathematician Albert W. Tucker, drew on the concepts developed by RAND Corporation scientists Merrill Flood and Melvin Dresher and posed "the prisoner's dilemma", which goes as follows...

This is an example of game theory, the branch of mathematics that employs simulations to investigate the maths behind decision-making. Using game theory, we can determine which choice will benefit you the most in the prisoner's dilemma.

Analysis

Each person has two choices, to cooperate with their partner (don't confess) or to defect (confess).

• If A cooperates and B cooperates, then A gets one year in prison.
• If A cooperates and B defects, then A gets four years in prison.
• If A defects and B cooperates, then A gets zero years in prison.
• If A defects and B defects, then A gets two years in prison.

Therefore, if you are person A:

• Cooperating gets you either one year or four years in prison.
• Defecting gets you either zero years or two years in prison.

Person B has made up their mind. And given that one year in prison is worse than zero years, and four years is worse than two years, no matter what they've chosen, you're better off defecting.

Let's say your partner is just as good at game theory as you. They would come to the same conclusion, right? So you'd both confess everything to the police officer and you would each end up with two years in jail, when if you had both stayed silent you each would've only gotten one. By acting in self-interest, making what seemed to be a rational decision, you're actually worse off.

Social Contract Theory & Contractarianism

Social Contract Theory asks you to imagine the "state of nature", a world without rules that 17th-century English philosopher Thomas Hobbes describes this hypothetical state in his book Leviathan...

Social Contract Theory states that in a world without rules where we can do as we please, there is nothing to protect us from others. And so, according to 'Contractualists', (the advocates of Social Contract Theory), it follows naturally that rational individuals would band together to form a larger society and create contracts to regulate said society.

'Contractarianism' is a form of 'Contractualism' that goes one step further, stating that morality is not something to be found, but rather a product of these contracts that humans make when in proximity for extended periods of time. Contractarians state that people realise there are simply more benefits to be found in cooperating than not cooperating, like, for example, getting only one year in prison compared to two.

And with contracts and continued cooperation, we learn to trust each other. This is why defection is more common among strangers; there are fewer social consequences, and the immediate rewards of betrayal can be tempting. However, among friends or close-knit communities, defection is much rarer because the social cost is high. Breaking an agreement in such contexts triggers a special kind of moral outrage, as our entire society is built on these unspoken social contracts.

If everyone agreed to these contracts, then the prisoner's dilemma would be solved. Contactarianism for the win! However, there are a few complications that prevent us from getting there.

Cooperation in Nature

The prisoner's dilemma is a simplified model for competitive interactions in societies. In the short term, defection seems like the winning strategy. In nature, if betraying someone helps you to survive, you will live to pass on those selfish traits, while others might not. That's just survival of the fittest. In a broader context, however, defecting can backfire.

If you betray your partner to save yourself you might walk free today, but who will trust you tomorrow? What about your next heist? Who will be your partner in crime? Your reputation as a liability will spread, and you may find yourself isolated, and cut off from future collaborations. In nature too, a purely selfish strategy often leads to a dead end, where you are cut of from the benefits of cooperation and struggle to survive. In computer simulations, inevitably we see a balance between cooperation and defecting in society. Take a look at this brilliant visual simulation from Primer.

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Those who exploit social contracts might argue that they never actually agreed to them in the first place, just as we never explicitly agree to follow the laws of the country we are born in. However, contractualists state that as long as you benefit from the overall impact of the contracts, you are expected to abide by them all.

Real-World Applications

Beyond the percentage of the population who naturally defect, the ambiguity of these situations means that those who would usually cooperate are often led to defect. Take the early days of the pandemic, for instance, when panic buying of toilet paper caused widespread shortages. The problem wasn’t a genuine lack of supply but the fear that others would buy out the stock first. People defected—hoarding supplies to protect themselves—when, in reality, if everyone had cooperated and bought only what they needed, there would have been plenty for all.

Time and again, we find ourselves ensnared by the dynamics of the prisoner's dilemma, but even knowing the theory behind cooperation and social contracts, it is still difficult to restrain yourself. Would you still cooperate if everyone else defected? Or to put it another way...

Takeaways

In the end, the prisoner's dilemma is a test of how far one might go for ideology. Would you stay in prison, or go without toilet paper, just because you believe everyone should cooperate? Conversely, would you launch a nuclear strike on another country, to prevent them from attacking you first? Sometimes defection seems like the only choice in moments of uncertainty.

No matter your take on cooperation and social contracts, once you learn to recognise them you'll see these dilemmas popping up everywhere—and they never really get any simpler.