Robert Nozick, answered from the texts and cited to the page.
A distribution is just if it arose by just steps from a just starting point. The three principles: (1) the principle of justice in acquisition specifies how previously unowned things may justly come to be owned; (2) the principle of justice in transfer specifies how holdings may justly pass from one person to another (gift, exchange, voluntary transfer); (3) the principle of rectification specifies what is to be done when previous injustices have produced the current distribution.12
The theory is historical: whether a distribution is just depends on how it came about, not on what pattern it exhibits. This is the decisive contrast with patterned and end-state theories — Rawls's difference principle, Marx's "from each according to his ability, to each according to his need," utilitarian aggregate maximization — all of which specify some structural property a distribution must have, and all of which require continual coercive interference with voluntary transactions to maintain.
The Wilt Chamberlain argument shows the point: any patterned distribution is destabilized when those who hold the goods voluntarily transfer them, and the only way to maintain the pattern is by overriding voluntary choices. Liberty upsets patterns.
This principle uses historical information about previous situations and injustices done in them (as defined by the first two principles of justice and rights against interference), and information about the actual course of events that flowed from these injustices, until the present, and it yields a description (or descriptions) of holdings in the society.Anarchy, State, and Utopia, pp. 152–153
I. A person who acquires a holding in accordance with the principle of justice in acquisition is entitled to that holding. 2. A person who acquires a holding in accordance with the principle of justice in transfer, from someone else entitled to the holding, is entitled to the holding. 3· No one is entitled to a holding except by (repeated) applications of I and 2.Anarchy, State, and Utopia, p. 151
The most influential single account of distributive justice in the libertarian tradition. The historical-versus-patterned distinction has shaped subsequent debate even among Nozick's critics. Cohen's Self-Ownership, Freedom, and Equality is the most rigorous Marxist critique, attacking the self-ownership premise on which the entitlement theory depends. Liberal egalitarians (Rawls, Dworkin, Kymlicka) maintain that pattern is required by justice and that the destabilization Nozick describes is the proper subject of redistributive correction rather than a refutation of patterning. The principle of rectification is widely acknowledged as underspecified in ASU, and Nozick himself never developed it in detail.