Let me first start off by acknowledging that any normative principles claimed by either side here are subjective by definition. This may seem like an obvious point, but in reading some of these pieces I came to the realization that leftist-anarchists are slamming property-based concepts on the basis of their normative justifications while failing to acknowledge the normative nature of their own principle-conclusions; subscribing to a sort of "Natural Law" based in their sense of "non-aggression" as opposed to the "propertarian" sense of "non-aggression" being coupled with property rights. This is not to say that their conclusions are incorrect (indeed they comprise at least part of the "propertarian" conclusion), but I just want to point out that there seemed to be a tendency to judge the "self-evident" nature of their principles as being somewhat above the normative notion of property-based liberty.
The first objection I'd like to pose is to the thought of property rights as a proxy for statism. This particular Proudhonian thought has been nagging at me ever since I began reading it in leftist-anarchist commentary. The thought goes as follows; Property owners claim absolute sovereignty over their property. And as such, have an explicit claim to make their own rules in regards to others who are on their property or using their property. This, in a real sense, is a de-facto state, as a business owner can now have a legitimate claim in giving orders to his workers, etc. This does not violate any property-based sense of liberty; therefore, a property-based sense of liberty can (and does) easily give way to authoritarianism or, in some sense, violates the idea of non-aggression.
I won't claim to speak for all (propertarian) libertarians here, but I think the premise is a little off. When it comes down to principle, I think a good amount of libertarians would tell you that any sense of "authority" given to the property-owner is consensual. In other words, I don't think a property-owner who "calls the shots" is making any type of authoritarian claim on another person. He is, without explicitly invoking it, threatening the withdrawal of consent for the second party's imposition onto his own property.
Let's say that I invite you over to my house for dinner. You sit on my couch and proceed to light a cigarette. I, not particularly liking the smell of cigarettes, ask you to do so outside. It seems to me that the anti-propertarian anarchist would ask me what kind of claim I have to such dictatorial rights to tell this man what to do. But, as the understanding property-rights theorist would rightfully claim, I wouldn't be making a claim on your right to smoke at all. What is being acknowledged, instead, is an implied understanding that you are not the owner of the property, and I am well within my rights to ask you to leave at any time. The same would apply if I had lent you a pair of shoes and asked you not to muddy them. I wouldn't be making a claim as to what you can or cannot do with your feet. I would be simply acknowledging the implicitly conditional nature of our arrangement. You do not own my shoes. Therefore, if you wish to use my property, you do so on certain conditions. And if you do not agree, then I retain my right to remove you from my property.
This is inherently different than the statist claim to authority (although the difference is apparently somewhat subtle). Anarcho-socialists claim that the state claims total-land ownership and therefore assumes authoritarian powers, and that the only propertarian objection to this power is that the state's property claim is illegitimate. But I reject this on many grounds.
I don't believe that most libertarians believe that the state is trying to make any real claim to land ownership (although we often criticize them for acting AS IF they do). If they were making such explicit claims, then I'm sure libertarians would also fight them on these grounds as well. The imposition of a "property tax" alone would seem to refute an explicit claim to state-ownership though. Instead, I believe they are making an explicit claim to power through contract (the Constitution). Now, on these grounds, I believe many propertarian anarchists (particularly anarcho-capitalists and voluntaryists) would argue that THIS claim is unfounded - as none of us were alive to sign such a contract.
In any case, the point of their objection is understood. If the state did somehow stake a legitimate claim to property that somehow usurped all of our individual property rights then, leftist-anarchists claim, we'd have no problems with their actions at all. I have to both agree and disagree here. If they did have a legitimate property claim (and they don't), one would expect the same level of exposition the non-smoker had on the smoker. It would not be an absolute authoritarian claim. Rather, the claim would simply be a looming threat to remove the person or persons from your property if they do not wish to follow your wishes.
This relationship of property to influence or power is undeniable, and it has many philosophical consequences. The leftist-anarchist may ask to what extent one would have power to remove someone from their property. And in truth, there is an un-ended debate in this arena among "propertarians." Some even go as far as to say you would have a right to injure or kill anyone who would trespass on your property. But few would support that notion as a right, and even less would act upon it. But it does remain a dilemma.
Many other dilemmas have been pointed out, particularly those surrounding the concept of self-ownership. Leftist-anarchists claim that seeing a sense of property in one's self lends credence to the idea that one could willfully sell one's self into slavery (and indeed many libertarians DO believe there is nothing ethically wrong with this). Another claim is to when, if at all, an individual comes into owning his own body. Indeed, in some sense, it is the parent(s) who physically creates the child from a part of themselves. Would a propertarian society lead to the literal ownership of children by their parents? If so, what keeps them from relinquishing ownership to the child at age eight-teen? And, in an even broader concept, what of the possibility of a single entity (system of matter) that contains more than one unique entity? There are many more questions that arise in this vein.
These are very valid points. And I won't sugar-coat my answer here; I don't have any concrete intuitive refutations for these objections. And that tells me I need to broaden my ethical construct so that I can. But what these objections don't do is shake my faith in the libertarian sense of property rights. I'll explain:
It seems the main thrust of the leftist-anarchist view is that a sense of absolute private property, especially in the application of self-ownership, leads to a slippery slope of justification for slavery. Thus, it seems they'd rather couch rights in the sense of non-aggression as opposed to property. But I'm not sure these two concepts are as mutually exclusive as they claim; and, in fact, maybe they're not really even different things.
The claim is made that liberty is a manifestation of property; and thus an inequitable sense of liberty arises from an inequitable reality of property distribution. But other libertarians (including myself) believe in somewhat of a reciprocal notion; the flip side of the liberty-coin if you will. We believe that property is a manifestation of liberty. In fact, there is not even a sense of property until man has used his free will to act upon matter to shape or use it to some end. It is a free man who makes something his property in this way. This may provide some insight into a refutation for these leftist-anarchist objections in some sense.
Using this model for the relationship of property to liberty, maybe slavery (meaning the actual ownership of another person) isn't explicitly possible, ethically speaking, after all. It seems to me, in some sense, that the transfer of property titles is an explicit relinquishing of physical control over something. But it's not apparent that actual control over one's body can even truly be relinquished (without death, some other total loss of consciousness, or consent to make one of these two things a reality).
In some ways, we already recognize the partial reality of this phenomenon in regards to death; all property claims are generally relinquished to those next in line or back to the community in some sense. And even as for that person's body, we don't dig up people hundreds of years later to examine their bones and burden ourselves with some concept that this person still owns their body. Yet once alive, we certainly don't generally accept the claim that someone other than them could hold title over them. A similar case could even be made regarding the objection of a child as property. In some sense, although the mother is willfully feeding and providing nutrients and materials to help the child grow, at some point there is a recognition that the child is a self-contained being with some direct, nearly unrelinquishable control over his own body, if not consciously.
It seems to me, intuitively, that the sense in which the ownership of self cannot be transferred to others is evident in the concept of contracts. Here, we have a consensual agreement to offer something in exchange for something else (typically). Why bother with an institutional framework to acknowledge such agreements if we could simply literally sell ownership of our selves for some explicit purpose? I think it's because maybe there is no real sense in which we can relinquish control of ourselves. As such, contracts are not absolute in that sense. We don't abandon control or claim over our concept of self to "work" for someone else. Instead, we have a contract with someone who wishes to employ our work; one in which either party is free to leave at any time. It's not inherent that some relinquishment of self would not be possible through contractual means (indentured servitude). But it doesn't follow that we have to ethically accept the idea that one wouldn't still have some ultimate claim over self, even if we talk about one's body in terms of property.
Let's be clear here. I'm not concrete on these refutations, they are just my natural reactions to the objections. But I'm convinced that someone can (and probably has) refuted such objections to property-based libertarianism.
There is something that I'm generally more clear on, and I think it's an important point to make. Natural Law theorists have had quite a time trying to refute Hume's Guillotine when arguing with leftists all across the spectrum. And rightfully so. When it comes down to it, you simply can't derive an "ought" from an "is." But it's important here to note that, by their very own standard of criticism, such people will eventually have to fall on their own sword. Whether through some egalitarian sense of virtue, justice, or equity, leftists have to come to the table knowing that their preferences are just as subjective as the ones they criticize so vigorously. And likewise, there are objections to and consequences for their denial of property in some sense.
Remember the libertarian claim that property is manifest in liberty? If we have no absolute sense of property as a right, and thus a person or group of people is said to have just claim over something, what of the person who labored to acquire the item? Is he not, in some sense, retroactively robbed of his liberty; when he spent his time and effort to produce something - and you make some future claim over this labor that has already been expended? Is this really that different from slavery? Is it not even more morally contemptible in some sense?
As stated, the concept of property and wealth itself is a direct result of exerting one's time and labor into something. They speak of the employer as a proxy for dictator (and concocting a good vs. evil story is a powerful story-telling tool) but what is to be said of the businessman who toiled his whole life away, exchanging his labor with other free people, in order to build up enough capital to acquire a factory? What is to be said to him when you tell him that the product of his own sweat and tears is not rightfully his, simply because what he has been able to afford to himself is "inequitable" with that of what can be afforded by those whom he has contracted employment for?
If we lived in a world where all demands can be satiated, and in which no man had to labor; where the earth simply blessed us with materials ready for our direct consumption - then I might be more sympathetic to the views of some idea of social consensus regarding distribution. But as man must pour his labor into the world around him, it seems inherently unethical to not recognize at least some sense of property rights. Any undermining insight seems suspect and arbitrary.
If there is no direct concept of property (as a product of labor) then who are the gate-keepers? Who decides who has control over what resources? Do we extend control in a completely equitable fashion, evenly amongst us all? Or do we invoke some moralistic sense of social justice, and do so according to need? If we do the latter, what is to be said of equality? If we do the former, what is to be said of subjective marginal value? Is it not true that people have different needs and wants that will not be satiated by equal distribution of resources? Will people be able to trade such control? If so, how would that operate different than a market? If someone wishes to labor for X resource because they hold it in high subjective value, will we laud the sellers of X as dictators for employing their labor? Will all of these issues be decided by some council? How is this different than an authoritarian state (the few over the individual)? Will the issues be decided collectively (democratically)? How is this different than an authoritarian state (the many over the individual)? If we have no sense of ownership in even ourselves, then are we really going to be led to believe that individuals who have no claim over their own bodies somehow have a claim to the bodies of others and what they do with their time and labor and the product thereof?
I'm sure there are refutations for much of this as well. But you can see that neglecting the concept of property as an absolute has some strange consequences of its own. That's why it's so important to acknowledge that all of the concepts inclusive to these divergent views are normative in nature. Acknowledging this, I can't be left to inductively conclude that property rights, in fact, do exist, and that there are no flaws left to be resolved in the ideology. But what I can conclude, deductively, for the time being is that all other concepts for our interaction with each other and the world around us seem less applicable.