The "agreed geography" bit is a non-starter: obviously any immigrant is going to agree that the United States comprises the usual agreed-upon area. I'm not sure how an immigrant is supposed to have or cause problems with "agreed geography". As for "agreed identity", I think it's very clear that Americans share a national identity just as strongly as we share religious, ethnic, and linguistic identities.

The irony is strong here: America, so often criticized for "homogenizing" the world, for imperialistically forcing our culture on everyone else, for raising the Golden Arches in every country on earth, is here criticized for not being homogeneous enough, for being too splintered and too open. The hypocrisy here is staggering.

One more point: I am nearly finished with a fascinating book on the causes, ideals, and effects of the American and French revolutions. It's clear from reading the book, at least in my opinion, that far from requiring a homogeneous society, strong democracy actually requires the opposite. A vibrant democracy needs political conflict (not in the violent sense), needs factions and interest groups and contrary agendas if it is to remain strong and protective of its citizens' rights. America has that active political culture, courtesy of a widely non-homogeneous society. Much of Europe does not. America's political strategy (at least internally) has been to enshrine oppositional politics, to embrace inclusion rather than exclusion. The European model, perhaps best exemplified by the French Revolution, is the opposite, and as a consequence seems fairly limp in contrast. What are the current great European debates? I can't think of any. The American debates -- cloning, affirmative action, abortion, free trade, intellectual property -- keep American society sparking along.

A final comment on the above quote, specifically "they are certainly not going to vote for large overseas aid budgets, debt relief and opening up trade to poor countries." Um, hello? The US spends a rather large amount on foreign aid. Oh, there's the usual objection ("yes, it's a lot in absolute numbers, but in of GNP it's a pittance"). Of course, when you spend something like 4 of GNP on defence (*cough*Europe*cough*) you can afford to spend large percentages on foreign aid. On the other hand, when you spend vastly more money on defence, and use an awful lot of the resulting armed forces on providing security for, among other things, the aforementioned countries who spend almost nothing on defence, as well as policing the entire world more or less by yourself, well, you can probably be excused for spending slightly less (percentage-wise) on purely monetary aid. I imagine that if we included a certain amount of our defense spending in the foreign aid numbers (certainly valid the way I see it; it's aid we provide to a huge number of other countries), our percentage rises rather sharply. As for the "opening trade to poor countries" jab, I don't see Europe embracing free trade with "poor countries" in any real way. On the other hand the US has the precedent of NAFTA, and a generally more receptive free trade tradition (recent presidential backsliding notwithstanding). Finally, I might be a little more impressed with Europe's foreign aid if they made some sort of halfway reasonable attempt to make sure they weren't just propping up dictators, funding terrorists, etc…

There is no closed American community with an ideal of sharing resources, and that is why the US is a third-world country in infant mortality and grinding poverty of a kind utterly unknown in Europe.

Well, there's no closed American community, no. But there's an open American community with an ideal of sharing resources. Not as many as we probably could, but the ideal is there. The US infant mortality rate is 6.76/1000 births (ref). In 1996, with 7.2/1000 births, the US was 24th among industrialized nations (ref). Denmark, Belgium, and Austria all had IMRs of ~7/1000 (ref) as of 1996, and a glance at the same table reveals that most "third world" countries have IMRs in the teens, if not the 20s and 30s or higher. As for "grinding poverty unknown in Europe":

Average per capita income in the European Union was 33% below U.S. levels in 2001, with only Switzerland, Norway, and Denmark posting income levels within 20% of the U.S. figure.

Now, per capita doesn't mean there's no poverty here, but it does imply that our average standard of living is rather higher than the European one.