…is where both Libertarians and Socialists go off the rails. Libertarians call it a “natural right”; Socialists sneer at that, and they’re correct. Wolves have no deeds to their range, and herbivore herds don’t get title to the grasslands.
Just because something isn’t “natural” doesn’t mean it isn’t useful, though. Cultivating plants isn’t “natural”, either, nor are cell phones. Societies evolve, just like creatures do. The policies and procedures — customs — of societies are much more mutable than the genes that control physical traits, so the process is faster, but the principle is the same: Those societies which adopt customs that are advantageous survive and prosper, and eventually partially or wholly displace the societies whose customs are less advantageous.
Private property began as a confluence of personal property and robbers sharing the swag. Few if any societies lack the concept of personal property — “my knife”, “my breechclout” and the like are generally accepted as valid assertions, although societies differ greatly as to how personal property is asserted and defended. When a band or tribe managed to defeat another, the leader or chief saw to the distribution of the spoils, with the largest share going to his trusted subordinates and a good bit dedicated to bribing his challengers and competitors for the leadership position to remain quiescent. Spoils thus distributed became the personal property of the recipients.
The invention of agriculture caused an extension of that principle. Agriculture requires control of territory, of land in which plants can be planted and cultivated. It produces a surplus compared to the hunter-gatherer-scavenger lifestyle, but a portion of that surplus must be devoted to defending the territory, not just against competing agriculturalists who would like to use it, but against the hunter-gatherer-scavenger bands, which can’t tell the difference between cultivated plants and naturally-growing ones except for the abundance, which naturally attracts them. If the tribe is to grow, another portion of the surplus must be allocated to territorial expansion, because the more territory it controls the more it can grow and the larger it can become.
Agriculture, and the tracts of territory devoted to it, must be managed. Management is hard, and as the territories became larger with expansion the task of managing them grew beyond the capabilities of a single tribal chief and his coterie of assistants. That’s especially true because neither the chief nor his subordinates were primarily selected for management ability — competition for leadership was mostly based on strength.
The solution was deputies. The tribe’s territory was divided up into smaller tracts with a sub-leader or subchief assigned to each one. That reduced the management problem to something a single leader could more readily accomplish. Such assignments were, of course, made to the people the chief could trust, which is to say, to the people who were already his subordinates and supporters, and the assignment was made in terms of ownership by analogy: The territory of a conquered tribe was divided up among the chief’s subordinates in the same way that the personal property of a defeated tribe had been.
The assignment was not without conditions. The newly assigned “owners” of the sub-territories were required to remain subordinate to the chief and to the main tribe as a whole, and the agricultural produce could not be kept in its entirety by the new management; a portion of it had to be returned to the main tribe. Owners had to muster for defense of the tribe’s territory against competitors desiring expansion, with such musters managed by the chief; more subtly, owners had to muster against insubordination, when one of their number decided to no longer accept the authority of the central tribe or chief, or to expand his sub-territory at the expense of one of his neighbors.
Implementation details differed widely, and still do, but already we can see the main features of the system of “private property”: the central authority (“Government”) allows individuals or small subgroups “possession” or “ownership”, and guarantees “title” (protection of that right of “ownership”) to the property against both external (“defense”) and internal (“theft” or “robbery”) threats, so long as the “owners” remain subordinate and pay a portion of the proceeds back (“taxes”). That’s still the way it works today. If someone tries to use your private property without permission, the sheriff will come and run them off — but if you don’t pay your property taxes or try to manage the property in ways insubordinate to the Law, that same sheriff will come and run you off, and the County Court will assign that property to somebody else.
When industrialization came along the system was extended and generalized. “Private property” no longer simply means land or territory; it may mean a bank account, part interest in an industrial enterprise, or something that’s entirely a construct, like “intellectual property”. The main features endure.
Why did the system continue? It’s obviously unfair — that is, it violates the conditions of survival for a hunter-gatherer-scavenger tribe by devoting huge chunks of resources to single individuals or favored groups, rather than dividing them up according to what the tribe members need to survive. If the roving members of the tribe don’t bring what they find back and share it with the others, especially the females, the tribe dies out. Private property is emphatically not sharing, and in fact (if it is to work) calls for equitable sharing must be treated like attempts at territorial aggrandizement and forcefully resisted. How did the custom get established?
The short answer is “evolution”. Private property got established by mutation of customs, and was continued and expanded by the process of evolution. Societies which adopted private property became more prosperous than those that did not, and eventually marginalized or supplanted their less “advanced” neighbors in exactly the same way a mutation for greater strength allows an animal species to marginalize or supplant its competitors for the same ecological niche.
(A longer answer, specifying what feature of the system actually creates the advantage, is beyond the scope of this essay, beyond noting in passing that it derives from the management problem that evoked the system in the first place.)
Libertarians are wrong. Private property is not a “natural right”; it is a custom of society like any other, and like any other custom it can be changed or eliminated. But Socialists are wrong, too — private property is a custom that evolved by the same mechanism that gave a tiger its teeth, that is, societies that adopt it survive and prosper better than those that do not. It’s at least curious to note that many of the people who are loud in their approbation of Darwin et. seq. against “creationists” are equally loud in the condemnation of the result of a process they nominally approve.