Locke gives the closest argument that matches my thinking about private property:
Though the earth, and all inferior creatures, be common to all men, yet every man has a property in his own person: this no body has any right to but himself. The labour of his body, and the work of his hands, we may say, are properly his. Whatsoever then he removes out of the state that nature hath provided, and left it in, he hath mixed his labour with, and joined to it something that is his own, and thereby makes it his property. It being by him removed from the common state nature hath placed it in, it hath by this labour something annexed to it, that excludes the common right of other men: for this labour being the unquestionable property of the labourer, no man but he can have a right to what that is once joined to, at least where there is enough, and as good, left in common for others.
That is, your limbs, organs, veins, and tissue etc belong to you. One must also add that your human capital belongs to you. Yes, it is unfair. People inherit different abilities, capacities, and tendencies from their parents. Then, their parents, and the environment in which they grow, shape their body and human capital. Therefore, given the exact same physical resources, two different people, due to differences in abilities and preferences, and chance, will end up with different outcomes. They will have different property. Not through violence, but through doing the what they think is best, subject to their own constraints.
Suppose it were technologically feasible to remove singing ability from one person, and implant it on another. Sting still owns his singing ability. He can decide voluntarily to part with it, but trying to take from Sting (who probably doesn't need it any more), and divide it among the less well-tuned among us will involve violence. Not messing with the distribution of singing ability will not (by definition).
Similarly, consider any two people. Let's call them Al and Bill. Suppose they each come to posses a seed for something. They'll do different things with them. True, the difference may have nothing to do with anything other than accidents of birth, or random variation in nature, but they will do different things. Say, Bill turns one seed into many and Al tosses it away. No violence was involved in bringing about the distribution of seeds.
Bill can, of course, decide he likes Al and give some of his seeds to Al. But, forcing Bill to give Al some of his seeds is violence.
There are basically two options:
A. All your stuff belongs to us
B. All your stuff is yours
(A) will always involve violence.
(B) will sometimes involve violence, as in,
- Al: Hey, Bill, nice seeds you got there ... Can you give me some?
- Bill: No.
- Al: Give me your seeds, or else …
Given something that always involves violence (A) versus something that sometimes might involve violence, I choose the one with less potential for violence, i.e. (B) "all your stuff belongs to you".
Of course, defining precisely what constitutes "your stuff" is not easy. But, one first has to accept that it is possible to define it.