From equality before the law to equality of resources, opportunity, and worth — and the recurring dispute over whether inequality is natural, just, or intolerable.
In what respects should people be treated as equals — and does equality demand sameness of outcome or only of standing?
Almost everyone now professes belief in equality, which only conceals how deeply they disagree about what it means. Equal before the law? Equal in political voice? Equal in resources, opportunities, welfare, or basic dignity? Aristotle warned that treating unequals equally is as unjust as treating equals unequally, framing a debate that has never closed. Modern egalitarians ask what should be equalized and why, while their critics reply that liberty and desert justify large inequalities, or that the real aim is not equality at all but that no one fall below enough. Reading these positions side by side shows that 'equality' names not one ideal but a family of rival demands about what we owe one another.
Peripatetic
Justice is a kind of equality, but proportional: equals should be treated equally and unequals unequally, in proportion to relevant desert. He distinguishes numerical from proportional equality and warns that democrats and oligarchs err by absolutizing one dimension of equality — freedom or wealth — as if it settled every distribution.
Nicomachean Ethics, Book V; Politics.
Social contract
Nature has made men so equal in body and mind that the weakest can kill the strongest — an equality of vulnerability, not of virtue. From this rough equality springs equality of hope, competition and hence the war of all against all; equality is a premise that makes the sovereign, not a value the sovereign must realize.
Leviathan (1651), ch. 13.
Classical liberalism
In the state of nature all are equal in the sense that no one has natural jurisdiction over another; all possess the same natural rights and are bound by the same law of nature. This is a moral and jural equality of standing, compatible with wide differences of talent, virtue and property acquired through labour.
Second Treatise of Government (1689).
Social contract / republicanism
Natural physical inequality is slight; the ruinous inequalities of wealth, rank and power are artificial, born with private property and civil society. A just order must limit inequality so that 'no citizen shall be rich enough to buy another, and none so poor as to be forced to sell himself', preserving the moral and political equality on which the general will depends.
Discourse on the Origin of Inequality (1755); The Social Contract (1762).
Enlightenment feminism
Women appear inferior only because they are denied education and treated as ornaments rather than rational beings. Since reason is the common endowment of humanity, justice demands the same education and civil standing for women as for men; the equality of the sexes follows directly from the equality of rational nature.
A Vindication of the Rights of Woman (1792).
Liberal political sociology
The steady advance of 'equality of conditions' is the providential fact of the modern age, at once irresistible and double-edged. It nourishes freedom and dignity but can also breed individualism, mediocrity and a soft despotism, or a passion for equality so strong that men would rather be equal in servitude than unequal in freedom.
Democracy in America (1835–1840).
Historical materialism
Merely legal and political equality leaves intact the class inequality of a society split into owners and workers, and even 'equal right' under socialism, measuring unequal individuals by one standard, remains a bourgeois limitation. Only in a higher communist phase — 'from each according to his ability, to each according to his needs' — is the narrow horizon of equal right transcended.
On the Jewish Question (1843); Critique of the Gotha Programme (1875).
Liberal egalitarianism
Behind a 'veil of ignorance' rational parties would choose equal basic liberties for all and, crucially, the difference principle: social and economic inequalities are just only if they benefit the least advantaged and are attached to positions open under fair equality of opportunity. Equality is thus the default, and inequality must earn its keep.
A Theory of Justice (1971).
Libertarianism
Distributive equality cannot be a goal of justice, because any pattern of holdings can only be maintained by continually interfering with people's free choices — 'liberty upsets patterns'. If holdings arise from just acquisition and voluntary transfer, the resulting distribution is just however unequal; imposing equality violates the rights of individuals treated as ends in themselves.
Anarchy, State, and Utopia (1974).
Welfare economics / capability approach
The real question is 'equality of what?' — and the right answer is neither resources nor utility but capabilities: the substantive freedoms people have to be and do what they have reason to value. Because people differ in how efficiently they convert resources into functionings, equal incomes can still leave deep inequalities of real opportunity.
'Equality of What?' (1979); Inequality Reexamined (1992).
Liberal legal philosophy
Government must treat all citizens with equal concern and respect, and the best interpretation of this is equality of resources rather than of welfare. A just distribution is 'ambition-sensitive' but 'endowment-insensitive': people should bear the costs of their choices but be insured against brute bad luck in talents and circumstance, an idea modelled by a hypothetical auction and insurance market.
Sovereign Virtue (2000).
Analytical Marxism / egalitarianism
Rawls concedes too much to inequality: if the talented demand extra pay as an incentive to be productive, they betray the egalitarian ethos justice requires, since a truly just society needs not only fair institutions but a shared commitment in citizens' own everyday choices. Equality is a demand on personal conduct, not merely on the 'basic structure'.
If You're an Egalitarian, How Come You're So Rich? (2000); Rescuing Justice and Equality (2008).
Analytic moral philosophy
Economic equality has no intrinsic moral importance; what matters morally is that everyone have enough — the 'doctrine of sufficiency'. Fixating on how much others have breeds envy and distracts from the real goal of ensuring no one lives below a decent threshold; a world of unequal but sufficient shares can be entirely just.
'Equality as a Moral Ideal' (1987); On Inequality (2015).