Don Boudreaux in the course of a nice post on Jane Jacobs' anti-nationalism quotes her thusly:
Nations are political and military entities, and so are blocs of nations. But it doesn’t necessarily follow from this that they are also the basic, salient entities of economic life or that they are particularly useful for probing the mysteries of economic structure, the reasons for the rise and decline of wealth.
This is right. But it's complicated, isn't it? The more economically open a nation's institutions are, the less significant is the nation as a unit of analysis. That is, once the political entity gets its institutions right, the economic entity becomes absorbed in a much larger economic network. When the institutions are all wrong, the nation gets cut off from the larger network. The circumstances in which it really makes sense to take the nation as the unit of analysis are those in which the nation is pathological. Sort of like, you don't pay that much attention to your liver until you get cirrhosis.
Political philosophy suffers from a paralell error. Normative mercantilism? The nation-state does require normative justification. But it is not therefore the primary or largest unit of social interaction demanding normative consideration. I think we've been retarded philosophically be the overemphasis on the nation. I'm certainly not sure how to reformulate the main questions of political-social philosophy for a super-nationalist context. So start thinking!