[via PROSEBEFOREHOS]
WIKIPEDIA: American exceptionalism is the theory that the United States occupies a special niche among the nations of the world in terms of its national credo, historical evolution, political and religious institutions and unique origins. The roots of the belief are attributed to Alexis de Tocqueville, who claimed that the then-50-year-old United States held a special place among nations, because it was a country of immigrants and the first modern democracy. The theory of American exceptionalism has a number of opponents, especially from the Left, who argue that the belief is “self-serving and jingoistic” (see slavery, civil rights and social welfare issues, controversial wartime policies, including the failure to aid Jews fleeing the Nazis), that it is based on a myth, and that “[t]here is a growing refusal to accept” the idea of exceptionalism both nationally and internationally.
Opponents of the notion of American exceptionalism argue that, while all societies differ in their history and social structures, the notion that the United 
States is uniquely virtuous overstates the importance of differences between the U.S. and other countries. They claim it ignores aspects of American history and society that contradict ideals of freedom and equality, such as slavery, segregation of schools in the South, the annexation by force of the Hawaiian islands and the American Southwest formerly Mexican territory, McCarthyism, the poverty and sometimes ghetto-ization of millions of citizens, the unequal quality of health care and education, and the genocide and displacement of the Native American population. MORE
RELATED: This is the idea, around since the founding fathers, and elaborated on by Alexis de Tocqueville, that the United States is a nation unlike any other with a special mission to build the “city upon a hill” that will serve as liberty’s beacon for mankind. But exceptionalism has taken an ugly twist of late. It’s become the angry refuge of the America that wants to deny the real state of the world. From an inspirational notion, however flawed in execution, that has buttressed the global spread of liberty, American exceptionalism has morphed into the fortress of those who see themselves threatened by “one-worlders” (read Barack Obama) and who believe it’s more important to know how to dress moose than find Mumbai. That’s Palinism, a philosophy delivered without a passport and with a view (on a clear day) of Russia. Behind Palinism lies anger. It’s been growing as America’s relative decline has become more manifest in falling incomes, imploding markets, massive debt and rising new centers of wealth and power from Shanghai to Dubai. The damn-the-world, God-chose-us rage of that America has sharpened as U.S. exceptionalism has become harder to square with the 21st-century world’s interconnectedness. How exceptional can you be when every major problem you face, from terrorism to nuclear proliferation to gas prices, requires joint action? MORE