The labor theory of property (also called the labor theory of appropriation, labor theory of ownership, labor theory of entitlement, or principle of first appropriation) is a theory of natural law that holds that property originally comes about by the exertion of labor upon natural resources. The theory has been used to justify the homestead principle, which holds that one may gain whole permanent ownership of an unowned natural resource by performing an act of original appropriation.
In his Second Treatise on Government, the philosopher John Locke asked by what right an individual can claim to own one part of the world, when, according to the Bible, God gave the world to all humanity in common. He answered that persons own themselves and therefore their own labor. When a person works, that labor enters into the object. Thus, the object becomes the property of that person.
However, Locke held that one may only appropriate property in this fashion if the Lockean proviso held true, that is, "... there is enough, and as good, left in common for others".
Locke argued in support of individual property rights as natural rights. Following the argument the fruits of one's labor are one's own because one worked for it. Furthermore, the laborer must also hold a natural property right in the resource itself because — as Locke believes — exclusive ownership was immediately necessary for production.
Jean-Jacques Rousseau later criticized this second step in Discourse on Inequality, where he effectively argues that the natural right argument does not extend to resources that one did not create. Both philosophers hold that the relation between labor and ownership pertains only to property that was unowned before such labor took place.