“I don’t hear from [Obama]… what an exceptional country we are,” former New York Mayor Rudy Giuliani recently declared. “[W]ith all our flaws we’re the most exceptional country in the world.”

Giuliani has been roundly -- and rightly -- criticized for his statements, since President Barack Obama often declares his belief in American exceptionalism. But is it true that we’re such an exceptional country? Obviously, every national politician is expected to say there’s something special and awesome about his or her country. In the U.S.’s case, however, there is plenty of reason to believe that it’s true.

How is the U.S. an exceptional country? Our history, of course, marks us as one of the first countries to embrace democracy, rule by a constitution, and many personal liberties such as freedom of speech and religion. Those things shouldn’t be forgotten. But much of the world has caught up, by adopting the values and institutions that we pioneered. So how are we special now?

Conservatives would point to things such as free-market capitalism, and to our individualistic, self-reliant culture. Those are important, and conservatives have championed them, while liberals haven’t always been so supportive. Does that mean -- as some conservatives claim -- that liberals somehow don't see the U.S. as exceptional?

No. Because there are some other deep, important aspects of our exceptional nature that liberals have worked tirelessly to protect and uphold -- often in the face of conservative opposition.

The first of these cuts right to the core of our identity as a nation. Most countries define themselves ethnically -- Hungary for the Hungarians, Russia for the Russians. But the U. S. defines itself by its institutions, not by blood, soil or tribe. This is demonstrated by the way our nation welcomes immigrants from all over the globe, of every race and religion.

This is the stereotype, but it’s true -- the U.S. really does stand out when it comes to assimilating immigrants. A 2008 study by the Manhattan Institute for Policy Research found that “[o]n the whole, immigrants in the United States are more assimilated than those in most European countries.”

Oxford economist Paul Collier has written the same thing, after making an extensive study of immigration and assimilation in rich countries.

Immigrants who came to the U.S. from eastern and southern Europe in the early 20th century, once known as “white ethnics,” are now simply called “white.” But will immigrants from Asia and Latin America repeat this success story? The data suggest they will. As the number of nonwhite immigrants has soared, the rate of interracial marriage has soared along with it, indicating that the cultural barriers separating whites from nonwhite immigrants are not that high.

For a particularly stark example of the power of American assimilation, one might only look at my own ancestral group -- Jews. In the U.S., 58 percent of Jews now marry non-Jews, and for non-Orthodox Jews the rate is 71 percent. Compare that to Jewish insularity throughout much of European history.

And of course, upward mobility for immigrants is very strong. You really can come to the U.S. and live out your dreams.

Maintaining a society that welcomes immigrants is a pillar of liberal politics in the U.S. Obama’s support of the DREAM Act is an important example.

The second way we’re exceptional is in American actions on the world stage. Like any nation, we’ve done bad things. But, at least in the last century, we’ve also stood out for the good we’ve done for the world. “Pax Americana,” the long peace and flourishing of human rights and support for democracy that accompanied American power, has made the U.S. more popular than other great powers such as Russia and China. Yes, our prestige took a tumble during the war in Iraq, but has since mostly recovered under the Obama administration.

Giuliani even recognizes this when he says:

What country has left so many young men and women dead abroad to save other countries without taking land? This is not [a] colonial empire[.]

He has a good point. In fact, in a number of areas, the U.S. has been an altruism standout. In a 1993 book, political scientist David Lumsdaine asserted that the U. S., unlike other rich nations, gives foreign aid out of humanitarian concerns, instead of to gain access to natural resources or other assets of poor countries. In a 2008 paper, New York University political scientists Bruce Bueno de Mesquita and Alastair Smith found some corroborating evidence for this hypothesis. A more recent paper by another team of researchers also found that the U.S. was among the most altruistic aid-givers, though two or three other countries were also generous.

Opposition to foreign aid, unfortunately, is a pillar of Republican policy. Fortunately, liberals have successfully resisted the push to eliminate it.

So when conservatives such as Giuliani say that liberals don’t think the U.S. is exceptional, they are wrong. They should remember that it’s liberals who fight against “preemptive” wars and for foreign aid, and liberals who struggle to preserve the U.S.'s status as the land of opportunity for immigrants. Exceptionalism isn't automatic. It isn't self-sustaining. You have to work to stay exceptional, and Obama and like-minded people have been doing their share of that hard work.

Family has been here for over 250 years and I generally give up on the United States as a viable country. I plan to tell my kids that unless they want to be trailer park trash and live off of welfare they should emigrate to another country.