In Orson Scott Card's book Children of the Mind, a character briefly discusses the idea of Center nations and Edge nations, which (at least in my copy) is expanded a great deal in the afterward.  He describes Edge nations as ones that rise in the shadow of another culture, and those cultures that overshadow all around them are Center cultures.  The key marks of a Center nation is that they are absolutely confident of their place in the world so that, while they control their own lands, they don't feel a need to prove themselves by controlling others.  When a Center nation is conquered, they remain intact culturally and assimilate their conquerors (think of how the Hyksos became Egyptian or the Romans became at least superficially Greek).  They see themselves as the center of the world and the pinnacle of human achievement.

Edge nations, on the other hand, always feel like outsiders trying to prove themselves.  They are often beligerent and aggressive about asserting themselves.  Empires are almost always built around edge nations that are looking to expand their sphere of influence.  Other times, they are simply the marginal nations that never really achieve greatness, often because another Edge nation is trying to keep them down.

(I'd recommend getting a copy of his book and reading his description which, for a variety of reasons, I won't post here in its entirety.)

Anyway, the key point of discussion with his Center/Edge perspective is the question, "Is the US a Center nation or an Edge nation?"  The nation began as the territory of an Edge nation (England) and its population is made entirely of refugees from Edge nations.  At the same time, the country certainly acts like a Center nation.  Perhaps the most common complaint about our country (at least among people who live in regions without an overwhelming US military presence) is that we are absolutely culturally arrogant.  We assume that, whatever we like, the world will like it as well and will want to be like us.

If the US is a Center nation, then what makes us a Center?  Is it the ideals that form the basis of our country, or is it an underlying philosophy that our people have adopted, which has become a part of our national identity, as well as our personal identities?  What makes a nation into a Center in the first place?  How does a people reach the point where they believe that everyone else in the world wants to be like them?

Discuss.