A: The American declaratino of rights is not the end of and be all for all things ethical, its just an appeal to an arbitrary authority.
B: Even there its justified in the end "as meets the essencial needs of decent living and helps maintain the dignity of the individual and of home," which is extremely modest and by no means justifying capitalist private property.
Your not justifying anything, your just talking about enforcement of what you allready assume to be an innate right.
Also what If I claim that what you claim is your property actually isn't ... then its just whoever shoots each other first ... thats not a justification thats just saying "I got a gun," your not addressing the question.
I addressed it most concisely. In reality, you own that which you can defend, or what you can get others to defend for you.
In modern America, the government decides what constitutes legal title to a piece of land, and will defend that title against those who try to take it from the owner.
In the early Middle Ages, land was controlled by local warlords (robber barons, the early "nobility" or leaders of armed men who arose as Rome withdrew from Europe) and their armed retainers... they owned or controlled a territory as large as they and their loyal fighting men could defend against all comers.
In modern times we've decided that, instead of how much armed force you can muster, how much land you can own is based on how much land you can BUY (and pay taxes on), but the claim is still backed by force.... government force, cops and courts and prisons.
Or in my case, inherit.... I inherited the family farm. Several generations of my direct ancestors and kinfolk have mixed their labor with this land, and it was the last owner's wish that it remain in the hands of his descendant.... think anyone else has a better claim?
Anyone who tries to take it from me is going to run afoul of the government that recognizes my title to the land... if they're lucky.
I'm being practical about it.... if you want to talk ivory-tower philosophy instead, then every piece of worthwhile ground on this planet has been taken by force from someone else at some point, probably several times. Unravelling that plate of spaghetti is going to be quite a trick.
Oh, I'm not dense... I know what you're trying to do. You're trying to come up with a way to remove the justification for private ownership of capital, of production: factories and businesses and whatnot. Will a factory get built if someone doesn't invest capital in it? No.... and those jobs will not be created. Someone has to have the savvy to amass enough capital and to build a business and make it profitable... they've "mixed their labor" into its creation and earned their ownership.
You can call it artificial if you like, but it is how we do things. If you replace it with another system, that system will be just as artificial....