Mike Brock put up this great post on the Shotgun and I wanted to take the opportunity to jot down a few more thoughts here.
Formally, property isn't all that difficult to understand. If X is A's property, then A has the right to exclude others from using X, where "using" is defined as broadly as possible.
"Exclusion" entails something like this: if X is A's property, then it is morally permissible for A to use violence to stop B from using X. While violence isn't normally permissible, the fact that X is A's property gives him the right to inflict violence on those who encroach on X.
Again, this is all very formal. The details of property -- not to mention property law -- go beyond my pay grade. However, there are probably only two ways to think about property and property rights, if one's moral view accepts them at all.
What should we think about property as "the right to exclude, using deadly force if necessary"?
Here's the first view: property rights are an extension of personal rights. Each of us comes equipped with a moral force field around our bodies. If another person enters this field without our permission, we are permitted to use violence to protect ourselves. The moral force field around our bodies is what prohibits others from (say) harvesting our organs without our consent.
On this view, there are certain actions we can take with respect to the stuff in the world that extends the force field around that stuff. Enveloped, our stuff gains the same level of moral protection as our own bodies; which means, basically, we can use violence to protect it, make use of it as we like, and so on.
Because the force field around our bodies is seamless, holding unconditionally, our property rights are absolute. There is only one field and it imposes the same moral requirements whether one is talking about body or land.
How we extend the force field is something of a "black box." I don't think the Lockean labor mixing story can be made coherent. The mere exertion of calories, as when one moves a stone across a field, seems insufficient to wrap both the stone and the field within the moral force field. "Purposeful labor" might work better - but maybe not.
In any event, I wish to leave the black box unexamined in order to turn to another way of thinking about property rights.
On this story, there is a gap between self-ownership and stuff-ownership. Think of it this way: the moral force field around the body can still be extended to cover stuff, but it loses a little bit of its punch once it is extended in this way. While it gives a person the right to exclude others from her body 100% of the time, perhaps it only gives her the right to exclude others from her stuff 99% of the time.
In short, the force field is weakened once it leaves its natural starting point in the body. Perhaps the more it is extended, the weaker it gets. At the limit, perhaps it dissipates entirely. Perhaps no one's force field is powerful enough to encompass an entire planet, or an ocean.
I think a good intuitive case can be made for a gap between self-ownership and stuff-ownership. Here is a case I presented in the comments at the Western Standard to try to demonstrate the idea (I cleaned it up a bit):
You buy all the land around Sally's house, which - to take the metaphor - means now there is a moral force field around her house. But let's make it a literal bubble: You put up walls of plastic stretching into the sky, all around Sally's house.Of course, "bent and manipulated a little" is extremely vague. One might think that I'm just waxing utilitarian about property rights. But I don't think that's quite it. I don't support taking Jones' property and handing it to Smith just because Smith would enjoy it better. That's what a utilitarian might support.
Given the right to exclude, Sally is obligated not to try to break through those walls. It would be morally wrong for her to cross over your land in an attempt to get food or water.
But of course you haven't coerced Sally, haven't done anything unjust to her from a libertarian point of view. At the same time, your actions have effectively crippled her autonomy.
So the question: suppose we accept that there is no divide between self-ownership and stuff-ownership. It's one force field and it applies to both you and to the stuff you've labored on (or something like that.) This means that when Sally cuts through the plastic, she's done violence to you. This means -- I'm assuming -- that you would be fully justified in shooting her in the head as she tries to make her escape. After all, she just tried to break into your property with a blow torch!
Intuitively, was it permissible to shoot her?
Now assume that there is a divide between self-ownership and stuff-ownership, one that works out in this way: self-ownership is absolute. No one can use your kidneys without your consent. But stuff-ownership is not absolute. Every once in a while, when it's necessary to give someone any shot at all of living an autonomous life, the stuff force field can be bent, manipulated a little.
In this case, if you refuse to ease your force field to accomplish some moral goal or protect certain values, Sally does nothing wrong when she ignores the field, and you are not justified in shooting her. Rather, you've committed murder, because you used violence in a way that, under the circumstances, was not permissible.
My thought is different: we adjust your property rights for the sake of Sally's liberty, but we adjust them as little as possible. I never said you had to let her live on your land: you just have to let her escape, without shooting her as she crosses your property.
So what does that mean? It means, I think, that property rights should be subordinated to liberty - or autonomy, if you prefer. But some property rights are necessary if one is to have the space to develop and grow into an autonomous individual.
My quibble is not with property as such so much as it is with the first vision of property I presented, one that takes the form of an unconditional right to exclude. We don't need to think of property in that way, and most people don't. Libertarians who cleave too tightly to property in that sense are doing themselves and the movement a disservice.