The fundamental purpose of property rights, and their fundamental accomplishment, is that they eliminate destructive competition for control of economic resources. Well-defined and well-protected property rights replace competition by violence with competition by peaceful means.
Armen Alchian, “Property Rights,” The Concise Encyclopedia of Economics
See a recent article on Alchian by Peter J. Boettke, “Why Did Armen Alchian Have to Teach Economists About Property Rights?”