Another way to ground morality starts from a simple thought: moral rules are the rules people would agree to if they were choosing the terms of living together. This is the idea behind social contract theory and its modern descendant, contractualism.
Hobbes and the state of nature
The English philosopher Thomas Hobbes (1588 to 1679) wrote Leviathan (1651) in the shadow of the English Civil War. He asked us to imagine a state of nature: life without government or enforceable rules. People are roughly equal in their ability to harm each other, resources are scarce, and no one can trust anyone else. The result would be a war “of every man against every man,” in which life would be “solitary, poor, nasty, brutish, and short.”
Rational people in this situation would agree to give up some freedom in exchange for security, accepting rules and a sovereign power strong enough to enforce them. For Hobbes, justice arises from this agreement: rules that make cooperation possible among self-interested people.
The prisoner's dilemma
Modern game theory illustrates Hobbes's point. In the prisoner's dilemma, each of two people does better by betraying the other whatever the other does, yet both end up worse off than if both had cooperated. Agreements backed by trust or enforcement let people escape this trap. Many moral rules, such as keeping promises and not stealing, can be seen as solutions to problems of this kind.
Locke and Rousseau
John Locke (1632 to 1704) argued that people in the state of nature already have natural rights to life, liberty and property, and that government exists to protect them; a government that violates them loses its legitimacy. Jean-Jacques Rousseau (1712 to 1778) argued in The Social Contract (1762) that legitimate laws express the general will of citizens pursuing the common good.
Rawls and the veil of ignorance
In A Theory of Justice (1971), the American philosopher John Rawls revived the contract tradition. He asked what principles of justice people would choose behind a veil of ignorance: not knowing whether they would be rich or poor, which race or sex they would be, what talents they would have, or what religion they would hold. Since no one could tailor the rules to benefit themselves, the choice would be fair.
Rawls argued that people would choose, first, equal basic liberties for all, and second, that social and economic inequalities are acceptable only when there is fair equality of opportunity and the inequalities benefit the least advantaged members of society. He called the last part the difference principle.
Scanlon's contractualism
The philosopher T.M. Scanlon, in What We Owe to Each Other (1998), developed a broader moral theory. In his view, an act is wrong if it would be forbidden by principles that no one could reasonably reject as a basis for general agreement. Morality is about being able to justify ourselves to each other. Scanlon compares individuals' objections one at a time rather than adding up benefits across many people, so a large total of small benefits cannot simply outweigh one person's grave loss.
Criticisms
- No real contract. No one actually signed. Defenders reply that the agreement is hypothetical: a test of fairness, not a historical event.
- Those who cannot bargain. Animals, infants and future generations cannot make agreements. Hobbes's version especially seems to leave out anyone with no power to threaten or help us.
- Self-interest. Critics argue Hobbes reduces morality to strategy, so a person who could cheat undetected would have no reason not to. Hobbes replied that no one can count on escaping detection, and a known cheat is shut out of the cooperation everyone depends on. Later contract theorists such as Rawls and Scanlon build fairness into the agreement itself rather than relying on self-interest alone.
Worked example: the accessible subway
A city is renovating its old subway system. Making every station accessible to wheelchair users, with elevators and level boarding, would cost a great deal and slow the project. Most riders can use stairs. Should the city pay for full accessibility?
Apply Rawls's veil of ignorance. Imagine choosing the policy without knowing who you will be: a commuter in good health, a parent with a stroller, an elderly person with bad knees, or someone who uses a wheelchair. You also do not know whether you will become disabled later, as many people do. Behind the veil, a rule that leaves some people unable to use public transit at all looks far less attractive, because you might be one of them.
Scanlon's test points the same way. Could a wheelchair user reasonably reject the principle “stations need only serve people who can climb stairs”? Very plausibly yes: it shuts them out of work, school and city life. Could other riders reasonably reject the principle “stations must be accessible”? Their objection is a higher fare or a delay, which is real but much less serious. Because Scanlon compares individual objections one at a time, the wheelchair user's grave burden is not outweighed simply because small costs are spread over many people.
A strict utilitarian might reach the same result or a different one, depending on the numbers. Contract theories make the answer depend on fairness and justifiability to each person instead.