Libertarianism holds that agents initially fully own themselves and have moral powers to acquire property rights in external things under certain conditions. It is normally advocated as a theory of justice in the sense of the duties that we owe each other. So understood, it is silent about any impersonal duties (i.e., duties owed to no one) that we may have.
Libertarianism can be understood as a basic principle or as a derivative one. For example, one might defend libertarianism on the basis of rule utilitarianism or rule contractarianism (see, e.g., Narveson 1988 ). Here, however, we shall focus on libertarianism as a natural rights doctrine.
Libertarianism is often thought of as “right-wing” doctrine. This, however, is mistaken for at least two reasons. First, on social—rather than economic—issues, libertarianism tends to be “left-wing”. It opposes laws that restrict consensual and private sexual relationships between adults (e.g., gay sex, non-marital sex, and deviant sex), laws that restrict drug use, laws that impose religious views or practices on individuals, and compulsory military service. Second, in addition to the better-known version of libertarianism—right-libertarianism—there is also a version known as “left-libertarianism”. Both endorse full self-ownership, but they differ with respect to the powers agents have to appropriate unappropriated natural resources (land, air, water, etc.). Right-libertarianism holds that typically such resources may be appropriated by the first person who discovers them, mixes her labor with them, or merely claims them—without the consent of others, and with little or no payment to them. Left-libertarianism, by contrast, holds that unappropriated natural resources belong to everyone in some egalitarian manner. It can, for example, require those who claim rights over natural resources to make a payment to others for the value of those rights. This can provide the basis for a kind of egalitarian redistribution.
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Libertarianism holds that agents are, at least initially, full self-owners. Agents are (moral) full self-owners just in case they morally own themselves in just the same way that they can morally fully own inanimate objects. Full ownership of an entity consists of a full set of the following ownership rights: (1) control rights over the use of the entity: both a liberty-right to use it and a claim-right that others not use it, (2) rights to compensation if someone uses the entity without one's permission, (3) enforcement rights (of prior restraint if someone is about to violate these rights), (4) rights to transfer these rights to others (by sale, rental, gift, or loan), and (5) immunities to the non-consensual loss of these rights. Full ownership is simply a logically strongest set of ownership rights over a thing.[1] There is some indeterminacy in this notion (since there can be more than one strongest set of such rights), but there is a determinate core set of rights (see below).
At the core of full self-ownership, then, is full control self-ownership, the full right to control the use of one's person. Something like control self-ownership is arguably needed to recognize the fact there are some things (e.g., various forms of physical contact) that may not be done to a person without her consent, but which may be done with that consent.
Full-self ownership is sometimes thought to guarantee that the agent has a certain basic liberty of action, but this is not so. For if the rest of the world (natural resources and artifacts) is fully (“maximally”) owned by others, one is not permitted to do anything without their consent—since that would involve the use of their property. The protection that self-ownership affords is a basic protection against others doing certain things to one, but not a guarantee of liberty. Even this protection, however, may be merely formal. A plausible thesis of self-ownership must allow that some rights (e.g., against imprisonment) may be lost if one violates the rights of others. Hence, if the rest of world is owned by others, then anything one does without their consent violates their property rights, and, as a result of such violations, one may lose some or all of one's rights of self-ownership. This point shows that, because agents must use natural resources (occupy space, breathe air, etc.), self-ownership on its own has no substantive implications. It is only when combined with assumptions about how the rest of the world is owned (and the consequences of violating those property rights) that substantive implications follow.