Property is private only because we’ve all agreed – or been forced to accept – that it should be. So it’s perfectly possible to imagine property systems in which what’s mine is yours, and what’s yours is mine, depending on how we’ve defined our relationship. There is a name for a form of social relation in which a person or people can claim rights to objects “owned” by another: usufruct. It’s common among archaic and tribal peoples: I own a tool, but if you need it, it’s yours as long as you don’t damage it. 

On saving communism from Marx.