A philosophical problem is determining what can, and perhaps more importantly cannot, be owned. There is considerable dispute over this subject and an example is the debate over whether people can be owned. A more recent example is the debate over ownership of genes. While each dispute needs to be addressed on its own merits, it is worth considering the broader question of what can and what cannot be property. It must be noted that this is not just about legal ownership.

Addressing this subject begins with the foundation of ownership, which justifies the claim that one owns something. This is the philosophical problem of property. Most people are probably unaware this is a philosophical problem as people tend to accept the current system of ownership, though people do criticize its particulars. But, to simply assume the existing system of property is correct (or incorrect) is to beg the question and the problem of property needs to be addressed without simply assuming it has been solved.

One practical solution to the problem of property is to argue property is a convention. This can be formalized convention (such as laws) or informal convention (such as traditions) or a combination of both. One reasonable view is property legalism, that ownership is defined by the law. On this view, whatever the law defines as property is property. Another reasonable view is that of property relativism, that ownership is defined by cultural practices (which can include the laws). Roughly put, whatever the culture accepts as property is property. These approaches correspond to the moral theories of legalism (that the law determines morality) and ethical relativism (that culture determines morality).

The conventionalist approach seems to have the virtues of being practical and of avoiding mucking about in philosophical disputes. If there is a dispute about what (or who) can be owned, the matter is settled by the courts, by force of arms or by force of persuasion. There is no question of what view is right as winning makes the view right. While this approach does have its appeal, it is not without problems.

Trying to solve the problem of property with the conventionalist approach does lead to a dilemma: the conventions are either based on some foundation or they are not. If the conventions are not based on a foundation other than force (of arms or persuasion), then they are arbitrary. If this is the case, the only reasons to accept such conventions are practical, such as to avoid harm (such as being killed) or to profit.

If the conventions have a foundation, then the problem is determining what it might be. One approach is to argue that people have a moral obligation to obey the law or follow cultural conventions. While this would provide a basis for a moral obligation to accept the conventions, these conventions would still be arbitrary. Roughly put, those under the conventions would have a reason to accept whatever conventions exist, but no reason to accept a specific convention over another. This is analogous to the ethics of divine command theory, the view that what God commands is good because He commands it and what He forbids is evil because He forbids it. As should be expected, the “convention command” view of property suffers from problems analogous to those suffered by divine command theory, such as the arbitrariness of the commands and the lack of justification beyond obedience to authority.

One classic moral solution to the problem of property is offered by utilitarianism. On this view, the theory of property that creates more positive value than negative value for the morally relevant beings would be the morally correct practice. It does make property a contingent matter since radically different conceptions of property can be thus justified depending on the changing balance of harms and benefits. So, for example, while a capitalistic conception of property might be justified at a certain place and time, that might shift in favor of a socialist conception. As always, utilitarianism leaves the door open for intuitively horrifying practices that manage to fulfill that condition. However, this approach also has an intuitive appeal in that the view of property that creates the greatest good would be the morally correct view of property.

A classic attempt to solve the problem of property is offered by John Locke. He begins with the view that God created everyone and gave everyone the earth in common. While God does own us, He is cool about it and effectively lets each person own themselves. As such, I own myself and you own yourself. From this, as Locke sees it, it follows that each of us owns our labor.

For Locke, property is created by mixing one’s labor with the common goods of the earth. To illustrate, suppose we are washed up on an island owned by no one. If I collect wood and make a shelter, I have mixed my labor with the wood, thus making the shelter my own. If you make a shelter with your labor, it is thus yours. On Locke’s view, it would be theft for me to take your shelter and theft for you to take mine.

This labor theory of ownership quickly runs into problems, such as working out a proper account of mixing of labor and what to do when people are born on a planet on which everything is already claimed and owned. However, the idea that the foundation of property is that each person owns themselves is an intriguing one and does have some interesting implications about what can (and cannot) be owned. One implication would seem to be that people are owners and cannot be owned. For Locke, this would be because each person is owned by themselves, and ownership of other things is conferred by mixing one’s labor with what is common to all.

It could be contended that people create other people by their labor (literally in the case of the mother) and thus parents own their children. A counter to this is that although people do engage in sexual activity that results in the production of other people, this should not be considered labor in the sense required for ownership. After all, the parents just have sex and then the biological processes do all the work of constructing the new person. One might also play the metaphysical card and contend that what makes the person a person is not manufactured by the parents but is something metaphysical like the soul or consciousness (for Locke, a person is their consciousness and the consciousness is within a soul).

Even if it is accepted that parents do not own their children, there is the obvious question about manufactured beings that are like people such as intelligent robots or biological constructs. These beings would be created by mixing labor with other property (or unowned materials) and thus would seem to be things that could be owned. Unless, of course, they are owners like humans.

One approach is to consider them analogous to children. It is not how children are made that makes them unsuitable for ownership, it is what they are. On this view, people-like constructs would be owners rather than things to be owned. The intuitive counter is that people-like manufactured beings would be property like anything else that is manufactured. The challenge is, of course, to show that this would not entail that children are property. After all, considerable resources and work can be expended to create a child (such as IVF, surrogacy, and perhaps someday artificial wombs), yet intuitively they would not be property. This does point to a rather important question: is it what something is that makes it unsuitable to be owned or how it is created?