First of all, "property" is not the thing owned, but the natural right each human being has to be an owner (the right "to" property), and the socially-determined bundle of rights that define what people may own and what owners may do with their possessions. While the latter comes under prudence, it does so only to the extent that the human person's right to be an owner is not thereby unjustly infringed, inhibited, or prevented; the socially-determined rights of private property, in common with the natural right to private property, come under the virtue of justice, not prudence.
Once we understand that, we have the basis for understanding the nature of property. As the universal prohibition against theft demonstrates, the right to be an owner is a part of the natural law. As Dr. Heinrich Rommen noted,
"Thou shalt not steal" presupposes the institution of private property as pertaining to the natural law; but not, for example, the feudal property arrangements of the Middle Ages or the modern capitalist system. Since the natural law lays down general norms only, it is the function of the positive law to undertake the concrete, detailed regulation of real and personal property and to prescribe the formalities for conveyance of ownership. (Heinrich Rommen, The Natural Law, A Study in Legal and Social History and Philosophy. Indianapolis, Indiana: Liberty Fund, Inc., 1998, 59.)That is, every human being has the right to be an owner, but how that ownership is to be exercised is determined socially by the needs of the owner, other people and groups, and the common good as a whole - but without prejudice to the underlying right to be an owner. Everyone may therefore use what he or she possesses as he or she wishes, as long as he or she does not harm him- or herself, other individuals or groups, or the common good. No one may be deprived of the exercise of property except for just cause and through due process.
Property is important because, except for human labor itself, nothing connects a person to the common good in a more intimate or secure fashion. By denying (abolishing) private property, the human person is cut off from the "ability for doing" that property confers, that is, "power." "Power," as Daniel Webster observed, "naturally and necessarily follows property." Without property, the human person is in the power of whoever possesses property, and is subject to control, more or less complete, depending on the will of who owns.
This is because property is not the thing owned, but the set of social relationships that define how an "owner" relates to the thing owned, and to other people with respect to the thing owned. Property confers power because in all codes of law property is the right of control. When the right of control is taken away, property is abolished, that is, socialism is established.
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