In thinking and talking about rights, including property rights, it seems natural to put the argument in either moral or legal terms. From the former viewpoint, rights are part of a description of what actions are right or wrong. The fact that I have a right to do something is an argument, although not necessarily a sufficient argument, that someone who prevents me from doing it is acting wrongly.

A broad range of intellectual perspectives may be brought to bear on any important social institution. To this general rule, the institution of private property is no exception. The desirability of private property has been endlessly debated across the disciplines: philosophical, historical, economic, and legal. Yet there is very little consensus over its proper social role and limitations. Is it possible to find a unique solution to questions of property and private ownership, good for all resources and for all times? The famous defense of private property that is found in chapter 5 of John Locke's Second Treatise of Government answers this question in the affirmative, for Locke writes as though all property was given to mankind in common, and then seeks to find the quickest and most expeditious way to convert all common property into private property. His implicit, but undefended, assumption is that common forms of property are both undesirable and unstable, while private forms of ownership are always just the opposite. Yet his preferred method for moving from a commons to a regime of private property—the unilateral decision to appropriate by each actor—is one that has been frequently condemned as a sop to unbridled egotism, even though it is subject to two constraints: the first against waste, and the second requiring the appropria-tor to leave “enough, and as good” for others.

The typical method of acquiring a property right involves transfer from a previous owner. But sooner or later, that chain of transfers traces back to the beginning. That is why we have a philosophical problem. How does a thing legitimately become a piece of property for the first time?

In this essay, I follow the custom of distinguishing between mere liberties and full-blooded rights. If I have the liberty of doing X, then it is permissible for me to do X. But the mere fact that I am at liberty to do X leaves open the possibility that you might be at liberty to interfere with my doing X. Accordingly, liberties are not full-blooded rights, since my having a right to do X has the additional implication that others are not at liberty to interfere with my doing X. When it comes to mere liberties, interference is not a violation. You can violate rights, but you cannot violate liberties.

My aim in this essay is to explore the nature and force of “original-acquisition” justifications of private property. By “original-acquisition” justifications, I mean those arguments which purport to establish or importantly contribute to the moral defense of private property by: (a) offering a moral/historical account of how legitimate private property rights for persons first arose (i.e., at a time prior to which no such rights existed); (b) offering a hypothetical or conjectural account of how justified private property could arise (or have arisen) from a propertyless condition; or (c) simply defending an account of how an individual can (or did) make private property in some previously unowned thing (where “things” might include not only land, natural resources, and artifacts, but also, e.g., ideas or other individuals). The “original acquisition” to which such justifications centrally refer, then, may be either the first instance(s) of legitimate private property in human history (typically assumed to have been many centuries ago on earth), or only the first legitimate acquisition of some particular thing (which might, for instance, have occurred yesterday or occur in the future on Mars). But in either case, the justification will involve or entail the defense of one or more moral principles specifying how unowned (or collectively owned) things can become privately owned — that is, the defense of the kind of principles Robert Nozick has called “principles of justice in acquisition.”

In recent years there has been growing interest in the contrast between Humean theories of property, on the one hand, and Lockean and Rousseauian theories, on the other. The contrast is a broad and abstract one, along the following lines.

Suppose the prevailing distribution of property rights is unjust as determined by the relevant conception of distributive justice. You have far more than you should have under that theory and I have far less. Then I defraud you and in doing so reallocate resources so that our holdings ex post more closely approximate what distributive justice requires. Do I have a duty to return the property to you?

There are many good reasons for requiring me to return to you what I have taken. One is that while you may have no right in justice to all that you own, it does not follow that I do, or that I have a right to take it. Thus, requiring me to return the property to you is a way of recognizing that I had no right to take it from you in the first place.

Philosophers and lawyers are apt to view property law from different perspectives. At the risk of gross overgeneralization, philosophers who discuss property rights tend to focus on the abstract principles that underlie ownership claims, while lawyers are more likely to focus on the practical problems of adjudicating concrete disputes within the constraints of a functioning legal system. Lawyers, for example, are likely to be more sensitive than philosophers to the real-world problems of proof that often accompany legal claims of ownership. For a lawyer, the key question is not whether any given theory of property rights is true in some metaphysical sense, but whether, given the theory of property rights employed by a particular legal system, a litigant within that system can prove an ownership claim to the satisfaction of an officially constituted tribunal.

During the last forty years, the Aboriginal peoples of the Americas, of the British Commonwealth, and of other countries colonized by Europeans over the last five hundred years have demanded that their forms of property and government be recognized in international law and in the constitutional law of their countries. This broad movement of 250 million Aboriginal people has involved court cases, parliamentary politics, constitutional amendments, the United Nations, the International Court of Justice, the development of an international law of Aboriginal peoples, and countless nonviolent and violent actions in defense of Aboriginal systems of property and cultures. The Aboriginal peoples of New Zealand, Canada, and the United States have been at the forefront of the movement, and it is in these countries that the greatest legal recognition has been achieved.

The Industrial Revolution caused an expansion of our ideas of property to include other forms of wealth, such as innovations and productive techniques. And the modern age has caused a further expansion of our ideas of property to include inchoate items, particularly information. The Framers of the U.S. Constitution presumed that government not only took an expansive view of the nature of property rights, they also believed that such rights should be protected. To James Madison and the other Framers, property was a “broad and majestic term” that “embraces everything which may have a value to which man may attach a right.”

William Perm summarized the Magna Carta thus: “First, It asserts Englishmen to be free; that's Liberty. Secondly, they that have free-holds, that's Property.” Since at least the seventeenth century, liberals have not only understood liberty and property to be fundamental, but to be somehow intimately related or interwoven. Here, however, consensus ends; liberals present an array of competing accounts of the relation between liberty and property. Many, for instance, defend an essentially instrumental view, typically seeing private property as justified because it is necessary to maintain or protect other, more basic, liberty rights. Important to our constitutional tradition has been the idea that “[t]he right to property is the guardian of every other right, and to deprive a people of this, is in fact to deprive them of their liberty.” Along similar lines, it has been argued that only an economic system based on private property disperses power and resources, ensuring that private people in civil society have the resources to oppose the state and give effect to basic liberties. Alternatively, it is sometimes claimed that only those with property develop the independent characters that are necessary to preserve a regime of liberty. But not only have liberals insisted that, property is a means of preserving liberty, they have often conceived of it as an embodiment of liberty, or as a type of liberty, or indeed as identical to liberty. This latter view is popular among contemporary libertarians or classical liberals. Jan Narveson, for instance, bluntly asserts that “Liberty is Property,” while John Gray insists that “[t]he connection between property and the basic liberties is constitutive and not just instrumental.”

Writers of very different persuasions have relied on arguments about self-ownership; in recent years, it is libertarians who have rested their political theory on self-ownership, but Grotian authoritarianism rested on similar foundations, and, even though it matters a good deal that Hegel did not adopt a full-blown theory of self-ownership, so did Hegel's liberal-conservatism. Whether the high tide of the idea has passed it is hard to say. One testimony to its popularity was the fact that G. A. Cohen for a time thought that the doctrine of self-ownership was so powerful that an egalitarian like himself had to come to terms with it; but he has since changed his mind. I have tackled the topic of self-ownership glancingly elsewhere, but have not hitherto tried to pull together the observations I have made in passing on those occasions. The view I have taken for granted and here defend is that self-ownership is not an illuminating notion—except in contexts that are unattractive to anyone of libertarian tastes.

This essay deals with property rights in body parts that can be exchanged in a market. The inquiry arises in the following context. With some exceptions, the laws of many countries permit only the donation, not the sale, of body parts. Yet for some years there has existed a shortage of body parts for transplantation and other medical uses. It might then appear that if more sales were legally permitted, the supply of body parts would increase, because people would have more incentive to sell than they currently have to donate. To allow sales is to recognize property rights in body parts. To allow sales, however, makes body parts into “commodities”—that is, things that can be bought and sold in a market. And some view it as morally objectionable to treat body parts as commodities.