James Traub doesn’t think much  of the Quincy Institute:
The idea of American exceptionalism, once a civic faith, now has the ring of the quaint—and not only because America elected a callow bully as president a few years back. You have to go back a very long way—perhaps to the establishment of the institutions of the liberal world order and the Marshall Plan—to find a time when you could confidently say that America’s global role was more exceptionally good than exceptionally bad. In some quarters, the corpse of American exceptionalism is being prepared for burial. I felt as if I heard the first strains of the funeral music when I read that George Soros and Charles Koch—an icon of liberal globalism and a right-wing libertarian—have teamed up to finance the Quincy Institute for Responsible Statecraft, a think tank dedicated to reducing America’s global footprint.
Traub begins and ends his column with references to American exceptionalism, but he never actually defines what he means by it in this article. I have an educated guess what he thinks the phrase refers to, but I have to go back to other things he wrote to know what he’s talking about. Here he assumes that it is a given that everyone has understood in the same way, a “civic faith” that used to be shared and no longer is. The closest we get to a definition is his reference to a time when “America’s global role was more exceptionally good than exceptionally bad,” but that isn’t exactly what most people have meant by American exceptionalism in the last decade or so. This isn’t the first time that Traub has deployed the phrase to complain about critics of the foreign policy status quo. Back in April , he was focusing on progressives and Democratic presidential candidates, but the gist was the same: alas, poor American exceptionalism! In the earlier article, Traub does give us a definition: “the belief, born with the American Revolution, that the United States has a special destiny to spread its republican—later democratic and liberal—values abroad.” He is very worried that many Americans no longer share this belief.
One difficulty in talking about American exceptionalism is that there is no single definition that everyone agrees on. As a description, American exceptionalism is sometimes supposed to refer to things that have distinguished America from other societies because of the unique course of our national development. Ian Tyrrell summed it up  this way:
Seymour Martin Lipset, the eminent Stanford political sociologist, made a career investigating the many factors that led to this American exceptionalism. Until his death in 2006, Lipset continued to hold that the U.S. was not subject to the historical norms of all other nations.
In the 20th century, it was originally a phrase coined by Stalin  to attack communists that said that America would not go through a socialist phase of development. At other times, it is intended as an expression of ideological mission and a claim to the right of global “leadership.” This is the Madeleine Albright version where the U.S. leads because “we stand taller and see further” than others. It is often more narrowly used by hawks to talk self-righteously about the use of American power and to excuse our government from having to abide by the same rules that everyone else has to follow. That is the Mitt Romney version where the U.S. is always a “force for good” and those that believe in “American exceptionalism” never apologize for their country in the sense of acknowledging error or making amends for past wrongs. There is another, much older kind of American exceptionalism–the kind that John Quincy Adams might have recognized–that extols the U.S. as an example of liberty to the world. Richard Gamble contrasted this older American exceptionalism with the contemporary one beloved of interventionists in a 2012 article  for TAC:
The shift from the old exceptionalism to the new did not happen all at once. The examples of John Quincy Adams and his son Charles show that the old and the new have existed for a long time, perhaps since our beginning as a people. There were new exceptionalists among the old and there remain old exceptionalists among the new. But where the old once predominated in how Americans thought about where they came from, who they are, and how they ought to relate to the rest of the world, now the new does. William Graham Sumner believed he witnessed the tipping point in 1898, when, to use Walter McDougall’s image, the U.S. turned from Promised Land to Crusader State.
The old exceptionalism was consistent with the ethos of American constitutional democracy; the new is not. The old was an expression of and a means to sustain the habits of a self-governing people; the new is an expression of and a means to sustain a nationalist and imperialist people. The old exceptionalism suited a limited foreign policy; the new suits a messianic adventurism out to remake the world.
As these different versions suggest, there is no single American exceptionalism, and the definition is contested and can change over time. One kind of American exceptionalism may be on the way out, but that could be because it is being replaced by another, older alternative whose time may be coming again.
Traub makes some other odd comments near the end of the article:
Similarly, one can be horrified by Trump’s decision to unilaterally abrogate the nuclear deal with Iran without fooling yourself about the danger of Tehran’s decision to blow through caps on uranium enrichment. It’s hard to avoid the conclusion that the lesser-footprint crowd is rearranging the world’s problems in order to fit their doctrine.
I would argue that Iran’s moves to increase enrichment in response to Trump’s relentless economic war are a direct result of the decision to abrogate the nuclear deal, and we should be concerned about the former but not yield to irrational fear-mongering about what it means. I don’t think critics of Trump’s Iran policy at the Quincy Institute or anywhere else are “fooling” themselves about the potential dangers here. On the contrary, the most vocal critics of this policy have been warning for over a year that reneging on the deal and reimposing sanctions could lead to just such an undesirable situation, and they are among the first to warn about the dangers of a disastrous war between the U.S. and Iran. Traub wants to paint critics of the status quo as hopelessly naive, but none of his targets is arguing what he claims.
He suggests that “the lesser-footprint crowd is rearranging the world’s problems in order to fit their doctrine,” but he is just asserting this. As far as I can tell, that’s not true at all. It is probably more accurate to say that the “lesser-footprint crowd” doesn’t assume that all of the “world’s problems” are the responsibility of our government to solve. Many of those problems will have to be addressed through multilateral cooperation when possible, other problems may just have to be managed, and some are truly not our business. If there is one thing that the “the lesser-footprint crowd” agrees on, it is that the U.S. is quite bad at solving many of the “world’s problems” and has tended to make many of those problems worse through our unwanted meddling. The “lesser-footprint crowd” description is quite fitting for what many antiwar progressives and conservatives hope to create, since it suggests that our government will be stepping in fewer messes and stepping on fewer nations. That is what John Quincy Adams recommended, and it is what George Washington advised in his Farewell Address, and it is what the U.S. should be doing in the future.