You see, that's the problem. You're using the Oxford Dictionary and the Merriam-Webster Dictionary. When you really should be using the Leo Strauss Dictionary.

Seriously, though. Proposition nations think they've totally beaten the blood and soil and boundary "problem." However, proposition nations do actually have borders, and border enforcement. Instead of a physical terrestrial border, they are ideological borders. In a proposition nation, patriotism is as easy as saying "I agree." (I.e. with the proposition of the proposition nation). And treason is as easy as saying "I disagree." If you disagree, then you'll be socially sanctioned, and maybe even criminally sanctioned.

The reason why modern American politics, sans the Alt-Right, come off as loopy, is because they're little more than various factions bickering with each other over the slight and subtle nuances of the proposition.