Justice
From the harmony of Plato's soul to Rawls's veil and Sen's capabilities — 2,400 years of asking what each is due.
Each star is a thinker or work; solid lines draw the constellation of a school, dashed threads the passage of ideas between eras.
Select any point on the timeline to read about it.
All entries by era
Justice 420 BCE – 2030 CE
From the harmony of Plato's soul to Rawls's veil and Sen's capabilities — 2,400 years of asking what each is due.
- 380 BCE
Plato, Republic. Against the claim that justice is merely the interest of the stronger, Plato defines it as harmony — each part of the soul and each class of the city doing its proper work. Justice becomes an inner order, the health of soul and state alike, not just fair dealing between people.
- 340 BCE
Aristotle, Nicomachean Ethics. Aristotle distinguishes distributive justice, apportioning goods according to merit, from corrective justice, restoring balance after a wrong. His analysis of proportion and equity (epieikeia) frames the vocabulary of fairness that law and philosophy still use today.
- 533 CE
Justinian, Institutes. Roman law distils justice into a famous formula: 'the constant and perpetual will to render to each his right' (suum cuique). Ulpian's maxim, enshrined in Justinian's compilation, ties justice to enforceable legal entitlement — a bridge from ethics to law.
- 1274 CE
Thomas Aquinas, Summa Theologiae. Aquinas weaves Aristotle's justice into a Christian order of natural law grounded in eternal reason. Justice becomes both a cardinal virtue directing us toward the common good and a standard by which human laws may be judged just or unjust — a measure above the ruler's will.
- 1739 CE
David Hume, A Treatise of Human Nature. Hume calls justice an 'artificial' virtue — not a natural instinct but a convention that arises because it is useful, given moderate scarcity and limited generosity. Justice, especially over property, is a human construction sustained by its benefits to society.
- 1785 CE
Immanuel Kant, Groundwork. Kant grounds justice in reason and human dignity: act only on maxims you could will as universal law, and treat humanity always as an end, never merely as a means. Justice ceases to depend on consequences and rests on the equal, unconditional worth of every rational person.
- 1789 CE
Jeremy Bentham, Principles of Morals and Legislation. Bentham makes utility the measure of justice: institutions are just insofar as they produce 'the greatest happiness of the greatest number'. Rights and law are judged by their consequences for aggregate welfare, launching the utilitarian tradition that still rivals rights-based justice.
- 1971 CE
John Rawls, A Theory of Justice. Rawls asks what principles we would choose behind a 'veil of ignorance', not knowing our place in society. The answer — equal basic liberties, plus inequalities that benefit the least advantaged — revives social-contract theory and dominates political philosophy for a generation.
- 1974 CE
Robert Nozick, Anarchy, State, and Utopia. Nozick answers Rawls with a libertarian theory: a distribution is just if it arose through just acquisition and voluntary transfer, whatever the resulting pattern. Redistribution that overrides individual rights, he argues, is itself unjust — sharpening the debate over equality versus liberty.
- 2009 CE
Amartya Sen, The Idea of Justice. Sen argues that justice should focus less on designing perfectly just institutions than on comparing real states of the world and removing manifest injustice. Building on his capabilities approach, he measures justice by what people are actually able to do and to be.
The milestones
c. 380 BCE
Plato, Republic
Justice as harmony
Against the claim that justice is merely the interest of the stronger, Plato defines it as harmony — each part of the soul and each class of the city doing its proper work. Justice becomes an inner order, the health of soul and state alike, not just fair dealing between people.
c. 340 BCE
Aristotle, Nicomachean Ethics
Giving each their due
Aristotle distinguishes distributive justice, apportioning goods according to merit, from corrective justice, restoring balance after a wrong. His analysis of proportion and equity (epieikeia) frames the vocabulary of fairness that law and philosophy still use today.
533 CE
Justinian, Institutes
The constant will to give each his right
Roman law distils justice into a famous formula: 'the constant and perpetual will to render to each his right' (suum cuique). Ulpian's maxim, enshrined in Justinian's compilation, ties justice to enforceable legal entitlement — a bridge from ethics to law.
c. 1274
Thomas Aquinas, Summa Theologiae
Justice within natural law
Aquinas weaves Aristotle's justice into a Christian order of natural law grounded in eternal reason. Justice becomes both a cardinal virtue directing us toward the common good and a standard by which human laws may be judged just or unjust — a measure above the ruler's will.
1739
David Hume, A Treatise of Human Nature
Justice as a useful convention
Hume calls justice an 'artificial' virtue — not a natural instinct but a convention that arises because it is useful, given moderate scarcity and limited generosity. Justice, especially over property, is a human construction sustained by its benefits to society.
1785
Immanuel Kant, Groundwork
Persons as ends, never means
Kant grounds justice in reason and human dignity: act only on maxims you could will as universal law, and treat humanity always as an end, never merely as a means. Justice ceases to depend on consequences and rests on the equal, unconditional worth of every rational person.
1789
Jeremy Bentham, Principles of Morals and Legislation
The greatest happiness
Bentham makes utility the measure of justice: institutions are just insofar as they produce 'the greatest happiness of the greatest number'. Rights and law are judged by their consequences for aggregate welfare, launching the utilitarian tradition that still rivals rights-based justice.
1971
John Rawls, A Theory of Justice
Justice as fairness
Rawls asks what principles we would choose behind a 'veil of ignorance', not knowing our place in society. The answer — equal basic liberties, plus inequalities that benefit the least advantaged — revives social-contract theory and dominates political philosophy for a generation.
1974
Robert Nozick, Anarchy, State, and Utopia
Justice in holdings
Nozick answers Rawls with a libertarian theory: a distribution is just if it arose through just acquisition and voluntary transfer, whatever the resulting pattern. Redistribution that overrides individual rights, he argues, is itself unjust — sharpening the debate over equality versus liberty.
2009
Amartya Sen, The Idea of Justice
From perfect institutions to real lives
Sen argues that justice should focus less on designing perfectly just institutions than on comparing real states of the world and removing manifest injustice. Building on his capabilities approach, he measures justice by what people are actually able to do and to be.