You don't own "Intellectual Property". You own a temporary monopoly on its reproduction in certain circumstances. But the creative work itself you don't own. Sure, if you paint a painting, you own the physical canvas, paint, and wood frame. Those are your property. But the depicted image? You don't own that. You own its copyright. Which is that temporary monopoly I described before.
I don't really understand the difference you place between physical property, and intellectual property. My ownership of both is imposed by the government. Without government support, I am sure I would lose control of both my physical and intellectual property very quickly (unless, in both cases, I started shooting people who tried to take them).