Citation?

How can he prove something doesn't exist? You'd have to show an example it does exist. Or they'd have to list every system and show why it's not positive.

I'm not expecting a mathematical proof; just trying to understand what he means by "positive" and how he would explain the development of IP law in every successful economy. Surely no reasonable person would state an absolute like this based on _nothing_, right?

> Or they'd have to list every system and show why it's not positive.

Again, I asked for a citation, not original work. If no one has found a good IP law system (for some value of "good") then surely some economist or IP law specialist has written a paper surveying the landscape, right? If this were not the case, it would be extraordinary!