As an example, he insisted that I was part-owner of the Washington Monument. I insisted it was none of mine. We insisted back and forth until he asked me for the why of my position. My test of whether I own something is whether I can sell it. Indeed, the working definition of private property is the rights held by the owner to keep, acquire and dispose of property.
Private property serves a vital social function often ignored or trivialized.
You don't have to be a keen observer to notice that privately owned property tends to receive better care than communally owned property. I've often said that I don't care that much about future generations. My actual conduct belies that sentiment. I own a nice home that is well cared for. Trees have been planted, rooms added, and many other improvements have been made that will outlast me and be available for that kid born in 2050.