There is nothing amiss with exceptionalism, never mind the slurs against it by the likes of NYU Law Professor Ronald Dworkin (in The New York Review of Books). To regard the United States of America as a country that's exceptional – meaning the likes of which cannot be found, provided the reason for this is laudable – is no liability, yet some people consider it so. Let's see what is exceptional about the US.
For one, it is has a system of laws, via its constitution, that lays out some rather firm principles according to which the citizenry is supposed to have its individual rights to life, liberty, etc., vigilantly protected. For example, this is probably the only nation in which (government) censorship is explicitly forbidden; one in which religion and government are explicitly kept apart; one in which it is against the law to force someone to testify against himself or herself (the fifth Amendment bans coercing anyone to incriminate himself or herself); one in which at least a reasonable attempt was made to protect private property rights (also in the fifth) even though this has been eroded by a repeated and perversely statist misinterpretation of the interstate commerce (Art. 1, Section 8, which mostly likely meant to regularize commerce, not have the government meddle with it constantly) and the takings clauses. And let's not forget the fact that America has been relatively hospitable to commerce and came quite close in some periods of its existence to amounting to a fully free market, capitalist economic system. All of these were exceptional when compared to most nations around the globe and are so even today.
Moreover, the country began with a declaration that explicitly demotes the federal government from being a sovereign ruler to that of a hired servant of the citizenry. This is quite exceptional, too.
But even if one leaves aside these somewhat legalistic features of America and simply looks at the country's history, which other country has ever had a civil war that amounted to an adjustment in its laws to conform to its initial revolutionary doctrine of everyone's equality under the law? More generally, few societies elsewhere have nearly completely abandoned rigid social classes the way these have been in America. (Sure there are economic classes but they are always in flux and membership is never legally inherited.) Moreover, which country in the world, other than perhaps Australia, has opened its borders to so many millions who wanted to live there and absorbed the immigrants so readily as has America?
Of course, the country hasn't existed without flaws such as its early unforgivable slavery and its vicious treatment of the natives (who, however, weren't entirely flawless themselves). Even among early African and American blacks some engaged in the slave trade.
Exceptionalism does not mean being pure, only having a markedly better record vis-a-vis justice and liberty compared with other countries in history and around the globe.
When it used to be a struggle to land on America's shores and millions still made the journey, the exceptionalism was nearly self-evident, for many of the reasons listed above. And hardly any intellectuals disputed this, although there have always been some detractors who wanted to demean the country precisely because of its exceptionalism. But in our time, when hundreds of thousands of European intellectuals have come here, many to take up influential positions at universities and colleges and in the media, the values to which exceptionalism had been related have gotten diluted, muddied, obscured and even denounced.
I have personally sat in the audience when a famous British philosopher, just one among many others, who had abandoned the UK for several US positions in prestigious academic institutions attacked nearly everything for which America has been taken to stand over the years and when asked how come he came here anyway, mumbled something about how it was a personal matter.
I am myself an immigrant and often express criticism toward my new country. Mostly, however, this is because of how determined so many are to throw overboard the principles that made the country exceptional, those laid out in the Declaration of Independence and the Bill of Rights. There is little question, however, that on the whole America has been exceptional – mostly in a good way but in some measure bad, as well. No one should accept the efforts of too many prominent people to deny this.