"Mine" is one of the first words babies learn, and by the time we grow up, the idea of ownership seems natural, whether we are buying a cup of coffee or a house. But who controls the space behind your airplane seat: you, reclining, or the squished laptop user behind you? Why is plagiarism wrong, but it's okay to knock off a recipe or a dress design? And after a snowstorm, why does a chair in the street hold your parking space in Chicago, while in...