There exist many theories. Perhaps one of the most popular was the natural rights definition of property rights as advanced by John Locke. Locke advanced the theory that when one mixes one’s labor with nature, one gains ownership of that part of nature with which the labor is mixed, subject to the limitation that there should be "enough, and as good, left in common for others" .
From the RERUM NOVARUM, Pope Leo XIII wrote "It is surely undeniable that, when a man engages in remunerative labor, the impelling reason and motive of his work is to obtain property, and thereafter to hold it as his very own."
Anthropology studies the diverse systems of ownership, rights of use and transfer, and possession under the term "theories of property". Western legal theory is based, as mentioned, on the owner of property being a legal individual. However, not all property systems are founded on this basis.
In every culture studied ownership and possession are the subject of custom and regulation, and "law" where the term can meaningfully be applied. Many tribal cultures balance individual ownership with the laws of collective groups: tribes, families, associations and nations. For example the 1839 Cherokee Constitution frames the issue in these terms:
- Sec. 2. The lands of the Cherokee Nation shall remain common property; but the improvements made thereon, and in the possession of the citizens respectively who made, or may rightfully be in possession of them: Provided, that the citizens of the Nation possessing exclusive and indefeasible right to their improvements, as expressed in this article, shall possess no right or power to dispose of their improvements, in any manner whatever, to the United States, individual States, or to individual citizens thereof; and that, whenever any citizen shall remove with his effects out of the limits of this Nation, and become a citizen of any other government, all his rights and privileges as a citizen of this Nation shall cease: Provided, nevertheless, That the National Council shall have power to re-admit, by law, to all the rights of citizenship, any such person or persons who may, at any time, desire to return to the Nation, on memorializing the National Council for such readmission.
Communal property systems describe ownership as belonging to the entire social and political unit, while corporate systems describe ownership as being attached to an identifiable group with an identifiable responsible individual. The Roman property law was based on such a corporate system.
Different societies may have different theories of property for differing types of ownership. Pauline Peters argued that property systems are not isolable from the social fabric, and notions of property may not be stated as such, but instead may be framed in negative terms: for example the taboo system among Polynesian peoples.