Property rights are a really fundamental part of any legal, or I might even just say normative system, a normative system in the sense of a set of rules that tells you what to do and what not to do. In any kind of moderately complex setting of different people, you're going to have to have rules that govern what's done with different things at different times. Even in say, Soviet Russia, they had a law of personal property. It wasn't the case you could just go down the street or go into someone's apartment and just take someone's shirt or take their broom that they swept the floor with. People had rights of a sort in personal objects there as well. That's a kind of very fundamental building block of any legal system. This is true for a couple of different reasons. One is that you need security of expectations in the resources that you use around you, in part so that you know what the effects of the decisions that you make are going to be. If you plow a field and plant seeds in it, you want to know that when all is said and done, you're going to be able to reap the harvest from that planting. Similarly, if you park your car on the street, you want to know that it's going to be there when you get back. Even when you're sharing things, that usually at the end of the day needs to be backed up by some kind of ultimate authority who's got control over what happens to stuff. You've got to have rules that govern that. Then property also turns out to be kind of important in a mirror image sort of secondary way as against government authorities as a way of spreading out decision-making power so it's not simply concentrated in a single set of hands that can act in an arbitrary manner. Property carves out a realm of freedom for individuals where they can pursue their own interests and sort of determine the ingredients of their own lives without needing a permission slip every time from a kind of central governing authority. That turns out to be quite important too and sets up as well a kind of a check or a rival center of power or rival centers of power as against any single centralizing authority that might be brought to bear.