Former New York mayor Rudy Giuliani instantly became the most notorious man in America when he said at a conservative dinner in Manhattan that President Barack Obama doesn’t love America.

He gamely tried to defend the remark for a few days before issuing a semi-mea culpa in The Wall Street Journal regretting his “bluntness” and saying he “didn’t intend to question President Obama’s motives or the content of his heart.”

That was probably the inevitable end-point once the words came out of his mouth, since it is an unwritten rule of American public life that only liberals are allowed to call their adversaries “unpatriotic.” Rudy Giuliani isn’t Nancy Pelosi or Harry Reid, who have both unloosed the “un-American” bomb on conservative opponents without any risk of getting hounded from polite society.

The reaction to Giuliani’s comment was so harsh, in part because he referred to Obama’s upbringing. This was taken as a sign that — in the argot of people constantly inventing a new vocabulary for their grievances — he was “othering” Obama, or playing to dark fears about the president’s past. Cue the wailing and gnashing of teeth.

But no “othering” is necessary. To be less patriotic than the average American doesn’t require any elaborate backstory or exotic beliefs — it is, as a matter of fact, a standard characteristic of the typical American liberal. The survey data are clear: There is a patriotism differential between the right and the left. Which doesn’t mean liberals don’t love the country in their own fashion, but their love is not reflected in old-fashioned pride in country.

A Pew Research survey last year found 46 percent of “steadfast conservatives” believed that the U.S. stands above all other countries; only 11 percent of “solid liberals” believed the same. Seventy-two percent of steadfast conservatives said they often feel proud to be an American; only 40 percent of solid liberals said they do.

Gallup headlined its write-up of a 2010 survey “One in Three Americans ‘Extremely Patriotic’: Republicans, conservatives, and seniors most likely to say so.” According to Gallup, 52 percent of Republicans and 48 percent of conservatives called themselves extremely patriotic; only 20 percent of Democrats and 19 percent of liberals did.

As a general matter, patriotic sentiment becomes more attenuated the further left you go. The late distinguished philosopher Richard Rorty, hardly a McCarthyite, once wrote a New York Times op-ed titled “The Unpatriotic Academy.”

He praised the left on campus for its championing of marginalized groups, before stipulating that “there is a problem with this left: it is unpatriotic. In the name of ‘the politics of difference,’ it refuses to rejoice in the country it inhabits. It repudiates the idea of a national identity, and the emotion of national pride.”

Edmund Burke famously said that “to make us love our country, our country ought to be lovely.” For the left, America is lovely to the extent it corresponds to a progressive vision of a European-style welfare state that leads from behind in international affairs and pounds its chest less about its own greatness and exceptionalism. The America it can feel proud of exists not in actuality, but in prospect, as a vessel for a distinct ideological vision.

Needless to say, it is hard to pursue this project while simultaneously feeling what George Orwell, in his definition of patriotism, called “devotion to a particular place and particular way of life, which one believes to be the best in the world.”

None of this means that questioning any particular politician’s patriotism will ever be considered in bounds — it smacks of questioning motives that are ultimately unknowable. But if Giuliani had stood up before that room of conservatives and said that liberals don’t feel about this country the way we do, he would have been on unassailable ground, and had the data to prove it.

Rich Lowry is the editor of the National Review.