The typical method of acquiring a property right involves transfer from a previous owner. But sooner or later, that chain of transfers traces back to the beginning. That is why we have a philosophical problem. How does a thing legitimately become a piece of property for the first time ? In this essay, I follow the custom of distinguishing between mere liberties and full-blooded rights. If I have the liberty of doing X , then it is permissible for me to (...) do X . But the mere fact that I am at liberty to do X leaves open the possibility that you might be at liberty to interfere with my doing X . Accordingly, liberties are not full-blooded rights, since my having a right to do X has the additional implication that others are not at liberty to interfere with my doing X . When it comes to mere liberties, interference is not a violation. You can violate rights, but you cannot violate liberties. (shrink)