I was once asked by an anarcho-capitalist what my path was to rejecting private ownership of capital. It was a misguided question, similar to asking "If you're not an ancap anymore, why do you believe in the state?" that required a lot of establishing what the alternative even is, but trying to answer led me to write this. Although this is old and not my current position, I think there's still value to it, especially for discussing property with ancaps, and I still draw on insights I explained, and wanted to keep my reply. Here is my response:
Well for starters, I understand "private ownership" differently than you probably do. It springs ultimately from a disagreement over what property fundamentally is. Capitalists define it as exclusive control of scarce resources. I define it as the responsibility for the consequences of one's actions as applied to labor as the action and property as the consequence, where one owns one's improvements only. I consider the issue of dealing with scarce resources where those scarce resources are not the product of labor to be a totally separate one from dealing with the products of scarce labor. To me, such natural wealth is something that nobody has the right to appropriate to the exclusion of others, having not created it, what right would the first improver have over anyone else to appropriate the unimproved wealth to their exclusion? It's a pretty clear injustice to me. Find natural wealth, make some improvement, exclude everyone else from the natural wealth. That's an unjust basis for property, even if it's an improvement over framings where all property comes from god or the king, it still contains a fundamental error.
A consequence of this is disagreement over whether one can own labor. To a capitalist (advocate type), it makes perfect sense, labor is a scarce resource. To me, it does not, because labor is not labor's product, action is not its own consequence. To a capitalist (owner type), they seek to buy labor, so that they might own its product. To me, labor cannot be bought because it cannot be owned. Only its product can be owned, and its product is owned naturally by the laborer.
If you apply this to a farm setting, why does the owner of the land own the crops grown on that land by the action of others? To the capitalist (advocate type), it is because the land is a scarce resource, the labor is a scarce resource, both were bought and combined and the result is a crop. As the owner of the labor and the land, why would they not own it? To me, the owner of the land does not own crops grown on it by others. The labor is not theirs to sell like that in the first place, and the land has a natural unimproved value that the landowner did not create which they are excluding the people who are actually tending to the crops from sharing in, and this exclusion is unjustified. Back when it was just farms, we would call this "feudalism".
If you apply it to a factory, why does the employer own the output of the factory? To the capitalist, it's because they own the capital and they buy the labor. To me, the worker naturally owns the product of their labor, even if it is created using somebody else's capital. They would at most owe the capitalist for the wear and tear on the capital, for its depreciation, but the capitalist does not rightly own the product of others' labor. That is their own. They may sell it to the capitalist if they like, just as they can sell it to anyone else. But the important point is, they can sell it to anyone else because it is their property. Whatever improvement is made, once the raw product is repaid for, is the property of the laborer, not the capitalist.
The difference comes down to, in socialism, one owns the product of their labor. In capitalism, one owns the product of their capital.
It isn't the ownership of capital per se that I disagree with. I don't see a problem with something like rental of machinery, unless the owner of the machinery owns the product of the laborer who uses it. It's the principle that the capitalist can appropriate the laborer's labor product that I consider to be fundamental. To do that is an act of theft. Under a restitutive understanding of justice as I use, the laborer so "exploited" by a capitalist develops a continually growing claim against the capitalist. And if this claim is not repaid by the capitalist, I see no reason why the laborer should not take capital of equivalent value as their own, call the debt settled, and produce as a freelancer. Or if the workers want to do so as a group, why they could not take ownership of the entire factory at once. Of course, the capitalist has to be repaid, in some way, for the loss of their capital. It is property too, after all. But to the degree that they deprive the workers of their labor's product, their profit is their repayment for the capital. Once the capitalist has taken in an income equal to their expenditure, the factory is the property of the workers, who have had their labor product taken from them. The effect of wages is only to slow down the rate at which the claims of the workers against the capitalist develop. But keep in mind, at the end of the process, the capitalist has as much wealth as they began with. They have not been stolen from, on net, they have stolen and been stolen from in equal proportion. They are left no worse off. They cannot make an idle income off of simply owning things.
To the capitalist (advocate) though, the labor product belongs to the capitalist (owner), not the worker, and no such claim against the capitalist is possible, and the capitalist will always continue to own the capital that they produce and the income that others produce for them, nothing may rightly touch it. It is held as private, untouchable, with nobody able to develop a claim against the capitalist for their loss of labor product.
And if you come back to say that the second laborer does not gain a property right in what the capitalist (owner) owned first as a raw material or partially-complete good, it's a double-standard in the capitalist (advocate) framework that the first laborer's improvement gives them property, but the second laborer's improvement does not. It is no more justification of this double-standard for the capitalist (advocate) to say that the second laborer would have owned it if they had been there first, than for a gay marriage opponent to say that men have as equal right as they do to marry women, and thus it is still equality of rights. Modifying it so that the first laborer owns their labor's improvements, and the second laborer owns their labor's improvements, and neither owns the natural wealth of the object labored upon, is an equitable way to express it that does away with the double-standard, similar to how saying that a man may marry who he loves and a woman may marry who she loves is doing away with the double-standard.
So when I say I'm against capitalism, I'm talking about capitalism as a productive organizational form, the hiring of wage labor by an owner of capital who owns their labor's product. When I say I'm against private property, I mean that I am against the framework of property where the capitalist owns the product of others' labor and their contribution does not earn them an equal stake to the extent that it is not remunerated by wages. To avoid confusion I try to avoid framing things in terms of private property unless pushed to rationalize the rhetoric used by others, as I'm quite happy framing things in terms of property, and consider "private" to be a useful distinction as opposed to regular "property" when the private property is capitalist property (i.e. used in a capitalist-form productive endeavor), as this is what it is used to justify by capitalists, and what it is used to oppose by socialists.
But you explicitly asked for the path. I mean to provide one. Now that you know the destination, perhaps the path will make sense. I think it really started from my consideration of restitution. Someone once framed six libertarian positions on the appropriate use of force:
I placed myself as number 3. Number 4 looked arbitrary (how much more than what is unavoidable can you use?), and number 2 seemed to suggest that any property you could get away with was essentially yours. So the principle is:
The repayment for a crime is the restitution for the harm.
But at some point I had to ask, given that value is subjective, and harm to property is harm to value, how can you ever equitably consider this? Perhaps based on price. But that wouldn't work very well, prices fluctuate all the time and can be set arbitrarily by crazy eBay buyers to $250,000 for half of a grilled cheese sandwich. And such fluctuation isn't a terribly useful way to determine what ideal justice would look like as it is based on agreement, a victim could arbitrarily say that they will only agree to 1 million dollars' restitution for bruising an apple that falls off of a display in a grocery store due to the infringer's clumsiness. It would be unconscionable to say that the infringer has the right to decline arbitrary claims by the victim as well, as is necessary to the formation of accurate prices. Cost is different, though. While prices of components are a factor of cost, those can be negotiated ideally. The cost to reproduce something being the cost of factors, that seems like the fairest basis that allows the aggressor to restitute the victim in the most exact way possible. Simply, an apple. But not at the store's price, of course, at the store's cost. The cost to the store of buying that apple, getting it delivered, and getting it put onto the shelf. In fact, the infringer might easily get around a stupid price claim by buying from another store and placing the apple on the shelf himself. Restitution by cost seems like the only way to ensure fairness.
Thus the principle was established:
The repayment for crime is the cost of restoring the victim to their pre-harm state.
When considering pure parity, 1:1 restitution, things get a little interesting.
I started thinking about land. What's the restitution for tresspassing? Well, I guess if you don't alter anything, they can't claim damages, so the restitution is zero.
Then on what grounds can you effectively prohibit it? Only if it causes actual harm.
Can you defend yourself from somebody who is not harming you or threatening any harm? No, to do so is to attack, or aggress, and it cannot be defense.
So in what sense do you own the land, and not just the things on the land? You don't really.
So why even say that you own land at all? It is essentially meaningless. So the principle was established to me:
That which needs no restitution is not a crime.
But let's consider, what was the cost to the landowner of the natural wealth of the land that they own? Any springs, perhaps, natural fertility, woods, and native wildlife. The cost to them was nothing. They improved things nearby and took claim of what was around it. They received possession of it by coincidence and good fortune. Suppose a logger comes by, and begins chopping down the trees on this land to make their house. The landowner says, "Stop! These are my trees!" The logger apologizes, not knowing this, and asks, "I will have to repay you for them then. What did it cost you to obtain them?"
The landowner did not pay anything to originally appropriate them, in actual fact. The cost to them was zero. And so, the logger takes some more trees, and leaves, knowing they owe no restitution.
It becomes obvious then:
Natural wealth has no cost to obtain.
From which it follows:
Stealing natural wealth is not a crime.
From which it follows:
Natural wealth is not property.
From which it follows:
Only the improvements (products) of labor may be owned as property, since only they had a cost to obtain.
From which it follows:
You only own the product of your labor.
Now consider, for example, a worker who takes something that they made at work and keeps it. What do they owe to their employer for their theft? As established earlier, the cost. Only the cost invested in the good so far before the worker labored on it, and the appropriate fraction of the wages for which the worker worked on it for their own use instead of the capitalist's. So then I reasoned, if the worker could do this and pay that restitution, and their labor product was worth more on the market than the cost of production, as is necessary for it to be profitable for the capitalist, the worker essentially owns their improvements. What this suggests of course, was obvious to me in the context of the new discoveries about the nature of property under restitutional justice:
You only own the product of your labor. You always own the product of your labor.
According to this principle though, the product of labor is identical to property.
I was never a big fan of self-ownership. I understood things in that framework at the time, and this made me reconsider it. Is a person the product of their own labor? No, they are as much a product of the labor of others. Surely attacking people was still wrong, this was a belief that exists without the belief in self-ownership, those who have never heard of self-ownership can still tell you that. And we certainly cannot sell ourselves as property, the problems with that idea are too numerous to list here, and it shouldn't be necessary.
So perhaps, we don't own ourselves. But then do we own our labor? It isn't the product of labor either, really. Nor does it exist until we exert it, and then it does not exist anymore. So then what do we sell to our employers? Do we sell time? We are measured by time, obviously, but how can time be owned? The only ways to exclude somebody from time are through murder, slavery, assault, restraint, and so forth, all things that are clearly aggression against the person. So what do we sell? Perhaps we sell our labor's product.
But to sell our labor's product it would require that we own it naturally in the first place to be able to sell it. And if we do own it naturally, then it is ours, we are not required to sell it to our employer, it is our right as owners to sell it to whoever we want, after restituting our employers for their part in its creation, of course.
So when an employer gains ownership de jure of our labor products that we create while working for them, is that not theft? Technically it is, though it's obviously not a malignant type, we continue coming back to be subtly stolen from day after day, because we also gain our income through wages.
But then that begs the question, how do you determine the amount of the theft occurring? Perhaps wages do not adequately cover that theft. After all, prices as a means of establishing the just restitutive value of something was previously rejected. How do you evaluate the purely subjective cost of labor in a way independent of price? You really can't, can you? Or can you, as the individual who experienced that cost firsthand, be the one to determine what the cost was? The object is your property, and the market demands your labor product. You can either let your employer steal it, and receive your wage, or you can take what is yours, tell the world what it is worth to you, and get what you can for it, the price that the market will bear, which you could unilaterally set, which the market could turn down should you overestimate the value of your improvements.
But even if you opt not to do that, to continue to be stolen from, it isn't any less a theft of your labor product, partially repaid by wages. It can't be voluntary even if you come back to do it, because it is yours naturally, and it is not yours to sell freely. Over time, a great, hidden debt would be generated. It magnitude is difficult to calculate, of course, as the real cost is concealed by the theft from being viewed by the market. How to discharge that debt then? If you demanded to be paid, the employer would simply say "That isn't the wages that you agreed to. Go back to work. This is nonsense." In a world without a state to give the employer de jure ownership of your labor product, it is still yours. So let us suppose you take the machinery that they give you for purposes of employment, the capital, from them, unable to collect on the debt from them. Suddenly, they do have to sit down at the table and reason with you as equals, if they intend to ever get that capital back.
If we assume a restitution-based system of justice (and how could anything else be justice?), and my conclusions about what constitutes property are correct, then the theft would be recognized, and while there are still deliberations on the cost of what you have each stolen from each other to ensure equity, if you were able to guess the right amount and "steal" an item worth only that amount, the debts cancel out, and the "stolen" capital is your property free and clear.
But if this happens once, and is established as precedent, it will happen again, and not in small numbers. Perhaps it would result in the full worker takeover of factories and the ousting of the previous owners. This would be a collectivization of the capital, a change from private property, capitalism, to, depending on the conditions that the workers decide upon, the collective, common, cooperative, or personal property of the workers that use it.
So it becomes that capitalism by the only sane standard of justice that I can conceive of, turns itself into socialism. Private property becomes no longer private, by the very mechanisms and principles that are required for property to be equitable in law (not meaning in distribution, though, as you can imagine, with effects like these, it would quickly become quite equitable in distribution, though never perfectly so, and that's not a problem per se).
So there you have, in its relative fullness, the thought process behind my transition from anarcho-capitalism to anarchism. Within anarchism, the distinctions like communist or collectivist or individualist or mutualist are just tendencies, as much rhetorical styles and expectations and hoped-for consequences and motivations as anything else, open to disagreement, and free to compete, but of course on equal ground, so this same reasoning supports Proudhon's mutualism as well as it supports Kropotkin's communism as well as it supports Tucker's individualist anti-capitalism. Although Tucker thought that capitalism was tolerable and that communism was not, and sought primarily to use the market to return to the worker in a capitalist firm the full product of their labor. A future-minded capitalist might be able to do this, by paying workers very well, but would lose their profit margins and their incentive to collect large amounts of capital by doing so. It would balance the scales between the capitalist and worker such that the capitalist does not on average make more money than a gambler or speculator with the same capital to work with. Without capitalists, large enterprises, where they exist, would be socialist in nature. So even if, as Tucker would have allowed, capitalists were permitted to continue being capitalists, fixing the errors in property theory, the double-standards and privileges, would destroy capitalism on its own, and leave only a free market behind it.