From giving each his due and the well-ordered soul to fairness behind a veil of ignorance and the entitlements of free exchange.
What is due to each — and how should the benefits and burdens of living together be shared?
Justice is the virtue we invoke when we ask whether an arrangement is fair, whether a punishment fits, or whether an inequality can be defended. Antiquity treated it as giving each his due and as a right ordering of soul and city; the moderns recast it around agreement, impartiality and rights. The twentieth-century debate crystallized in a clash between justice as fairness, chosen behind a veil of ignorance, and justice as entitlement, arising from legitimate acquisition and exchange. Reading these accounts together reveals that disputes about justice are often disputes about what people deserve and what we owe one another.
Ancient Greek (Academy)
Against the sophistic claim that justice is merely the interest of the stronger, Plato argues that justice is each part doing its own proper work — in the soul, reason ruling spirit and appetite; in the city, each class performing its function. Justice is thus a kind of inner harmony that is good for its possessor, not merely useful for its reputation.
Republic (esp. Books I–IV).
Ancient Greek (Peripatetic)
Aristotle distinguishes distributive justice — allocating goods and honours in proportion to merit — from corrective (rectificatory) justice, which restores equality after a wrong. Justice is a mean and, uniquely, 'the good of another'; treating equals equally and unequals unequally, in proportion to relevant desert, is its core principle.
Nicomachean Ethics, Book V.
Scholasticism / natural law
Justice is the constant and perpetual will to render to each his right (ius). Grounded in the natural law that human reason discerns in the eternal law, it governs our dealings with others and is the chief of the moral virtues directed to the common good; unjust human laws that contradict natural law lack the force of law.
Summa Theologiae, II-II, qq. 57–58; qq. 90–97 (on law).
Empiricism / sentimentalism
Justice is an 'artificial' virtue — not innate but a convention that arises because of moderate scarcity and limited human generosity. Its rules, above all stable possession and the keeping of promises, are useful conventions; we approve of justice from sympathy with the public interest it serves, not because it tracks a natural moral fact.
A Treatise of Human Nature (1739–40), Book III.
Deontology / German idealism
Justice concerns the outer conditions under which each person's freedom can coexist with everyone else's under a universal law. It is grounded not in consequences but in respect for persons as ends in themselves; even punishment is a demand of justice — the just penalty answers to the crime, not merely to social utility.
The Metaphysics of Morals (1797), 'Doctrine of Right'.
Liberal egalitarianism / social contract
Justice is fairness: principles chosen in an 'original position' behind a 'veil of ignorance', where no one knows their place in society, would be fair to all. Rawls derives equal basic liberties for each and the 'difference principle', under which inequalities are just only if they benefit the least advantaged.
A Theory of Justice (1971).
Libertarianism
Against Rawls, Nozick offers an entitlement theory: a distribution is just if it arises from just original acquisition and voluntary transfer, however unequal the result. 'Patterned' principles that aim at a preferred distribution require continual interference with liberty — 'liberty upsets patterns' — and taxation of earnings is likened to forced labour.
Anarchy, State, and Utopia (1974).
Capability approach / welfare economics
Sen argues that a theory of justice need not describe a perfectly just institution; it should help us compare actual states of affairs and remove manifest injustice. What matters is not the mere existence of just rules but people's real capabilities to lead lives they have reason to value.
The Idea of Justice (2009).