What’s Fair? The Idea of a Social Contract

Imagine you and a group of friends are stranded on an island. There’s no grown-up in charge. No rules. No one to settle arguments. Someone needs to decide who gets which chores, how food is divided, and what happens if someone breaks a promise. But nobody has the authority to just tell everyone what to do.

So you have to figure it out together. You have to agree on some basic rules.

Now imagine that the rules you come up with wouldn’t just be convenient. They’d be fair—and everyone would have a real reason to follow them, not because they’re scared of punishment, but because they genuinely think the rules make sense. How would you know if you’d found those rules? And how would you convince someone who disagreed?

This is the kind of problem that social contract theory tries to solve. It’s one of the oldest and most important puzzles in political philosophy: What makes a set of rules or laws something that everyone can rationally agree to follow?

There are lots of ways to argue that a rule is good. You could say it’s what God wants. You could say it’s “natural” or obvious to any reasonable person. You could say it makes everyone happier.

Social contract theory takes a different approach. It says: A rule is justified if everyone would agree to it, given the right circumstances. The justification doesn’t come from outside—it comes from the fact that people, using their own reasoning, would all say yes.

That might sound simple, but it raises a bunch of tricky questions. What counts as “the right circumstances”? Do we mean actual agreement, or just what people would agree to under ideal conditions? And what if people disagree about what’s good or fair—which they almost always do?

Philosophers who work on this stuff build models—simplified versions of reality—to try to answer these questions. Think of it like a scientific model: you can’t study the whole messy world at once, so you create a simplified situation that captures the important parts. A social contract model does the same thing for justification: it creates a simplified setting where we can figure out what rules everyone would agree to, and then use that to think about the real world.

Who Are the “People” in the Contract?

This is where things get interesting. When a philosopher builds a model of the social contract, they have to decide: who are the imaginary people who will do the agreeing?

There are two main approaches, and they disagree about something fundamental.

The Reductionist Approach

Some philosophers—often called “contractarians,” following thinkers like Thomas Hobbes—start from a tough question: “Why should I be moral at all?” If you’re a selfish person who only cares about your own goals, why would you ever agree to be restrained by rules that help other people?

These philosophers build their contract around self-interest. The imaginary people in their model are assumed to care only about their own well-being. They don’t start with any moral commitments. The point is to show that even these purely self-interested people would still agree to some basic rules—because cooperation is better than chaos, even for a selfish person.

This is a “reductionist” approach: it tries to show that moral rules can be derived from non-moral, selfish reasons. If you can convince a selfish person that morality is actually in their own interest, you’ve answered the question “why be moral?” in a very powerful way.

One reason this approach appeals to philosophers is that it’s robust—it works even if people are not naturally nice. As the philosopher David Hume once said, you should design your political system as if “every man is a knave,” even though that’s not really true. If you build a system that can survive selfish behavior, you’re in good shape.

The Non-Reductionist Approach

Other philosophers—often called “contractualists,” following thinkers like Immanuel Kant and John Rawls—think this misses the point. They argue that the people in the contract should already care about fairness and respect. They don’t need to be tricked into morality; they need to figure out which moral rules are the right ones.

In this approach, the imaginary people in the contract are given moral values from the start. They might be behind a “veil of ignorance,” not knowing whether they’ll be rich or poor, strong or weak, so they have to pick rules that are fair to everyone. Or they might be required to give reasons that no one could reasonably reject.

This approach is “non-reductionist”: it doesn’t try to derive morality from self-interest. It assumes that people already care about being fair, and the contract helps them figure out what fairness actually requires.

A Problem: Real People Are Messy

Here’s a difficulty that runs through all of this. The whole point of the social contract is to figure out what real people should agree to. But real people are complicated. They have different religions, different values, different ideas about what makes a good life. They’re biased. They make mistakes.

If you make the imaginary people in your model too idealized—say, perfectly rational and perfectly informed—their agreements might not tell us much about what we should do. A perfectly rational person might not care about religious freedom, because they wouldn’t have any irrational religious beliefs. But we do have religious beliefs, and we need rules that work for people like us.

On the other hand, if you make the imaginary people too much like real people, they might disagree just as much as we do. How do you get a determinate answer out of a model where the parties keep arguing?

This tension—between idealization and realism—is one of the central debates in contemporary social contract theory.

How Do They Actually Reach Agreement?

Even if you decide who the imaginary people are, you still need a way for them to agree. Philosophers have proposed several different mechanisms.

Bargaining

One idea is that the people in the contract bargain with each other, like two people dividing a pizza. They each want as much as they can get, but they also need to reach a deal—otherwise they get nothing. Game theorists have developed mathematical models of this kind of bargaining, trying to figure out which division a rational person would accept.

The philosopher David Gauthier argued that the “minimax relative concession” solution is the right one—the outcome where each person gives up the least compared to what they could have demanded. John Harsanyi and Ken Binmore have used a different solution, based on the work of mathematician John Nash. The problem is that there are many different bargaining solutions, and philosophers disagree about which one to use.

Aggregation

Another approach is to think of the contract as a kind of voting or averaging. Imagine that the imaginary people rank all possible rules from best to worst, and then you combine all their rankings into a single social ranking. If everyone has the same information behind a veil of ignorance, they might all rank things the same way—so “aggregation” is just a matter of doing the math.

Harsanyi used this approach to argue that rational people behind a veil of ignorance would choose rules that maximize average happiness. But this only works if you can compare one person’s happiness to another’s—which turns out to be surprisingly difficult.

Equilibrium

A third approach borrows an idea from game theory called an “equilibrium.” Think of it like driving on the right side of the road. It doesn’t really matter whether we drive on the right or the left, as long as we all do the same thing. Once a convention is established, no one has a reason to break it—you’d crash. This is an equilibrium: a stable pattern where no one wants to change what they’re doing.

Some philosophers, like Brian Skyrms and Ken Binmore, argue that the social contract can be understood as an equilibrium that emerges over time through repeated interactions. We learn to cooperate because it benefits us in the long run. The rules that stick are the ones that are stable—not just because someone wrote them down, but because people keep choosing to follow them.

This approach has the advantage of being dynamic: it explains not just what rules are good, but how they might actually come into existence. But it also raises a question: just because something evolves, does that make it right? An equilibrium that emerged through a history of exploitation and inequality might be stable, but that doesn’t mean we should keep it.

So What Does the Contract Actually Prove?

Let’s say you’ve built a model, defined the parties, and found a rule they would all agree to. What have you shown?

The strongest claim is that the contract creates the justification for the rule. There’s no independent standard of fairness—the fact that everyone would agree is what makes it fair. This is called “constructivism,” and John Rawls sometimes seemed to hold this view. He compared the contract to a fair game: if you’ve set up the rules of the game properly, whatever outcome emerges is fair by definition.

A weaker claim is that the contract is evidence that a rule is fair, not the source of its fairness. Maybe fairness is a real thing that exists independently, and the contract is just a tool for detecting it. On this view, the contract helps us figure out what’s already true, rather than making it true.

Most contemporary social contract theorists fall somewhere in between. They think the contract is a test: we use it to check whether our institutions can be justified to everyone affected by them. If a rule would be rejected by the imaginary parties, that’s a sign that something is wrong. If it would be accepted, that’s a reason to think it’s legitimate.

Why This Still Matters

The social contract tradition is still very much alive. Philosophers continue to argue about the right way to model the parties, the best mechanism for reaching agreement, and what the contract actually shows. But the core idea—that legitimate rules must be justifiable to the people who have to follow them—has become deeply influential.

It shows up in debates about constitutional design, about the limits of government power, about what counts as a fair distribution of resources. It’s the reason we care about whether laws are passed with broad support, not just by a powerful few. And it’s the reason we keep asking, in one form or another, that ancient question: what would you agree to, if you had to live by the same rules as everyone else?

Nobody has a final answer. But the fact that we keep coming back to the question is itself a kind of answer.

Appendices

Key Terms

Term	What it does in this debate
Social contract	A thought experiment that asks what rules everyone would agree to, in order to figure out what’s fair
Justification	The process of showing that a rule or institution is reasonable and worthy of support
Reductionism	The strategy of deriving moral rules from non-moral motives like self-interest
Non-reductionism	The strategy of starting with moral values and using the contract to figure out what they require
Veil of ignorance	A device that removes knowledge of your own identity so you have to choose rules that are fair to everyone
Equilibrium	A stable pattern where no one has a reason to change their behavior
Bargaining	A process of negotiation where parties try to reach a mutually acceptable deal
Constructivism	The view that the contract doesn’t just detect fairness but actually creates it

Key People

Thomas Hobbes (1588–1679) — An English philosopher who argued that without government, life would be “nasty, brutish, and short,” and that even selfish people would agree to a social contract for self-protection.
John Rawls (1921–2002) — An American philosopher who revived social contract theory in the 20th century with his famous “veil of ignorance” thought experiment. He argued that fair principles of justice are those we would choose if we didn’t know our own place in society.
David Gauthier (1932–) — A Canadian philosopher who tried to ground morality in self-interest using bargaining theory, arguing that rational people would agree to be moral because it benefits them.
Ken Binmore (1940–) — A British economist and philosopher who uses game theory and evolutionary biology to model how social contracts can emerge over time, like biological evolution.
Brian Skyrms (1938–) — An American philosopher who argues that the social contract can be understood as an equilibrium in repeated games, using the “stag hunt” as a key example.

Things to Think About

If you had to design rules for a society without knowing whether you’d be born rich or poor, male or female, healthy or sick—what rules would you pick? Would those rules actually be fair to everyone?
The bargaining approach assumes people are selfish. The non-reductionist approach assumes people already care about fairness. Which assumption seems more realistic to you? Does it matter which one is more accurate, or just which one leads to better rules?
Some philosophers say that hypothetical agreements don’t bind anyone—just because you would have agreed to something under ideal conditions doesn’t mean you agreed to it in real life. Is that a real problem, or is the point of the contract to reveal something deeper than actual consent?
If a social contract evolves naturally over time—through repeated interactions and conventions—does that make it legitimate? Or do we need to check it against some independent standard of fairness?

Where This Shows Up

Constitutional design — Many countries’ constitutions include ideas about what “the people” would agree to, and debates about constitutional reform often appeal to hypothetical agreement.
Video game design — Game developers sometimes think about what rules players would voluntarily accept in online games. The best-designed games are ones where players feel the rules are fair, even when they lose.
School and classroom rules — Teachers who let students help create classroom rules are using a kind of social contract idea: rules are more likely to be followed if everyone had a say in making them.
International relations — Treaties and international law often rely on the idea that nations should only be bound by rules they agree to—a kind of social contract between countries.

Why the Social Contract Is Different