A few things missing here, posed as a question:

Why should we want the US to be the largest (or one of the largest) economies in the world and/or maintain its position as a global superpower?

Maybe I’m missing something , but I didn’t see SA give a good and/or specific reason here (he makes some arguments about not wanting to decline, which I think makes sense but that would be true for really any economic organization...).

Of course I think there are a number of good reasons why it is good for the US to be the largest economy in the world, and for brevity I’d probably put them into two basic buckets:

A. some self-interested reasons: I’d rather be part of a nation-state that has more control over the global political economy than less control so that it is easier for me to have control over my own economic situation, I’d rather be part of a nation-state that is prosperous and can maintain that prosperity so that it is easier for me to maintain my own prosperity.

B. some (allegedly) selfless reasons: I’d like the global superpower to at least maintain some semblance of respect for / commitment to human rights, rule of law, democracy, freedom of speech/religion, a market economy and all that good old american pie stuff (I’m being snarky but I really do value those things) - don’t get me wrong, I understand there’s a lot of hypocrisy/inconsistency with how the USA actually operates, but this is the “USA-is-not-the-best-but-better-than-the-alternatives” argument, which I really do believe.

There’s a good argument that all the “human rights / rule of law / freedom of speech” stuff is just constructed-BS and that its worth trading off for high levels of growth (I’m Korean, and many Koreans see the military dictatorship after the Korean war as net positive since it allowed Korea to grow rapidly, in spite of major human rights abuses etc. which I don’t entirely disagree with), but I guess at the end of the day I’m old-fashioned enough to say that I value those things in and of themselves and that I wish them upon pretty much everyone that exists or has existed or will exist.

That all being said, my Chinese counterpart (or really anyone from any other country) can pretty much say the same thing as (A) and I can’t really give them a good reason to say that for some reason I (and the USA) deserve this position more than she and China (or anyone else and any other country in the world) does.

Therefore, when I say that I think it’s good for the USA to be the most powerful nation I have to (1) admit that it’s at least partially (if not more) motivated by A than B, in which case my position is not really any more valid than my Chinese counterparts and (2) hope it’s at least partially motivated by B, because then it’s actually a position that I believe(hope?) will actually benefit everyone involved.
This is of course all predicated on my moral beliefs that don’t allow me to say that my self-interest is always paramount, which I know many people just disagree with flat-out, which is fair - I pretty much am the same way, though I really do try (and most fail) to be another way, for reasons something like this: http://moreintelligentlife.com/story/david-foster-wallace-in...