As far as I can tell, most libertarians these days do not rely upon the labor theory of property anymore. It is kind of a silly doctrine to begin with, and Marx picked it up and ran with it, using it to show that all profit is theft. So these days, arguments for absolute property ownership tend to rest upon various sorts of first-use theory and the principle of non-aggression. That is, propertarians try to tell some story in which persons can unilaterally grab up unowned pieces of land and then point guns at everyone else, telling them not to come near. This is somehow represented as non-aggressive, even as it involves unilateral threats of violence against those who do not wish to give up their pre-existing ability to access whatever land has just been claimed.
I could go on about first-use stuff and I have before, but here I want to talk briefly about the labor theory of property. I wont give it much treatment because like I said, it does not seem to have much intellectual support anymore. It does however find occasional support among those who have taken intro to political science and one time read about John Locke.
In its simplest form, the labor theory of property says that people are entitled to the product of their labor. Immediately a problem appears: what exactly is the product of one’s labor? I can cut down a tree and make a chair, but that chair includes both my labor and the natural resources of the wood. How do I become entitled to both when I did not make both, especially given that my use of the tree prevents anyone else from using the tree in another manner? Nothing is purely the product of someone’s labor; it always involves natural resource inputs as well. And nobody made those. (Georgism is supposed to solve this problem)
That aside, consider what the consequences of the labor theory of property actually are. Libertarians like to accuse others of indirect enslavement, but if you actually thought about the labor theory of property, you would realize that it justifies direct enslavement. Children are the product of their parents’ labor. We even call child birth “labor.” More than that, two decades of parental labor and social labor go into making a child into a human adult. If anything is the product of human labor, it is cultivated, educated, and grown human beings.
Surely then, parents and society must be entitled to own children. They produce children and build them into what they wind up being. A consistent application of the labor theory of property then should result in total enslavement!
This whole line of thought is really weak. It is not even top five in justifications of property ownership. Nonetheless, I find myself occasionally confronted with this antiquated doctrine, online and offline, and so I thought it might be worth a post.