A: Why do you own something?
B: Because you bought it.
A: This certainly suffices to explain ownership in the overwhelming majority of cases, but what you mean is that if you own one thing you can exchange it for another. But why do you own things at all?
B: Because you work for them.
A: No doubt you own your labor in a more intimate way than your money, but this still seems to be a case of exchanging one thing you own for another.
B: But we are closer to an explanation if my labor is more mine than my money.
A: Right. But if we make labor the source of possession it seems to prove too much. Thieves can labor to acquire goods but stealing doesn’t transfer ownership, and if I land on a desert island with a fruit tree and pigs on it the fruit and the pigs are mine to use, whether I work for them or not, or even whether I know about them or not.
B: How can you say they’d be yours even if you didn’t know about them?
A: Assume I died of starvation having never found them. If some rescuer found my body by flying over the island and seeing both the trees and my corpse, wouldn’t he say something like “what a tragedy! He could have survived off of those trees!” In other words, the trees were mine to dispose of, even before I knew they were there.
B: So property is that which one can dispose of?
A: Isn’t that the right definition? Something whose very existence is ordered to my own existence, in such a way that I could even kill or destroy it to preserve myself.
B: Okay
A: And if this is right, then God as supreme good, creator and sustainer stands to all creation as his property.
B: This seems frightening. God could kill or destroy all creation?
A: That’s probably an important truth to know in some contexts, but for the moment we’re considering creation as ordered to God precisely as supremely good, so we can’t visualize him standing to creation like a tyrant seeking to maximally concentrate goods within himself to the exclusion of diffusing them to others.
B: So what about property then?
A: It looks like God stands to all as property because he creates it out of goodness, and so this explains in part why labor is closer to being one’s possession than money since labor formally relates to something that owes its existence to us, and so far as anything fits this description it does stand to us somehow as ultimate end.
B: But the labor isn’t enough.
A: Right. The basic relation of property is all things in lower strata of existence standing to all things in a higher strata.
B: So this means all things belong to all people! That’s communism!
A: There is a fundamental orientation of all things to all persons, and this is what the Church calls the universal destination of goods. But it doesn’t follow from this that just anyone has a claim to just anything, since we can’t assume the universal destination of goods is essentially a chaotic free-for-all.
B: Still, the justice or injustice of private property is built on top of and presupposes the universal destination of goods.
A: That’s right.