Even for someone as gaffe-prone as Joe Biden, this stands out. As he was wrapping up an interview with syndicated talk host Charlamagne tha God that aired Friday morning, the former vice president said, “If you have a problem figuring out whether you’re for me or Trump, then you ain’t black.” At a minimum, he’s overreading his standing with black voters — who support him by a margin of 78 percent over President Trump, according to the latest national Quinnipiac poll — because they see him as the candidate most likely to unseat Trump, not because of his overall track record. It’s a matter of pragmatism, not ideological and cosmic alignment, as Theodore Johnson put it last year.

Biden later walked his comments back on a call with black business leaders, reportedly saying that “I shouldn’t have been such a wise guy” and “I have never, ever taken the African American community for granted.” But he had already revealed a double standard that signified the opposite. It’s hard to imagine him, or most politicians, making the same claim, in any context, about any other demographic group.

Yes, Biden can boast of a track record with African Americans, which The Post’s Robert Samuels ably chronicled last year. He served as the number two for the nation’s first black president. Biden also has a comfort level with black constituents that many white politicians don’t. This was borne out in February when he received a resounding endorsement from Rep. James E. Clyburn (D-S.C.) and went on to resurrect his campaign by winning the Democratic primary in South Carolina — a state in which the majority of Democratic voters are black.

In response to Biden’s comments, senior campaign adviser Symone Sanders tweeted:

Indeed, it would be fair to take Biden’s remark as an attempt to contrast his record with Trump’s; even by Trump’s preferred metrics — the unemployment rate and stock market performance — Obama was a better president for black Americans. Still, even in jest, it’s one thing to say that black voters should support him and something different to say that black Trump voters aren’t really black. Over the past two decades, about 90 percent of black voters have sided with Democrats, according to exit polls. There were fervently pro-Trump black voters in 2016, and that will still be true in 2020. In the Quinnipiac national poll, Trump only had 3 percent black support, compared to Biden’s 81 percent. Polls vary, though, and it’s not out of the question that Trump could match his 8 percent from 2016, which included 11 percent among black men and 16 percent among black men with college degrees.

Whatever number he gets, the “ain’t black” notion is a litmus test Biden doesn’t seem to apply to other demographic groups. In the same Quinnipiac poll, Latinos preferred Biden over Trump 45 percent to 38 percent, and no one suggests that the 38 percent “ain’t” Latino. Former president Ronald Reagan is sometimes quoted as having said, “Hispanics are conservative, they just don’t know it yet.” That’s condescending, but still not the same as saying that Latino Democrats aren’t really Latino. Biden’s comment veers closer to Trump’s remark last year that “I think if you vote for a Democrat, you are very, very disloyal to Israel and to the Jewish people.”

SiriusXM Urban View radio host Clay Cane, who describes himself as a progressive and is a Biden supporter, told me, “Aligning yourself with anti-black policies does not erase your identity. There is a long history of black folks who advocate against each other for access to power and proximity to whiteness — but that doesn’t mean they’re not black.” Tara Setmayer, a black Republican and former GOP congressional staffer, told me, “As a conservative who supports Joe Biden, his comment was an unforced error that reinforces the stereotype that Democrats take black votes for granted.” She added, “I winced when I heard it.” When I reached Katrina Pierson, one of Trump’s most prominent black supporters and a member of his campaign team, she was blunt: “Only a white liberal can dehumanize black people to their face and get away with it. Joe Biden’s statement is the definition of white privilege.”

Recall that early on in Barack Obama’s first presidential run, he was seen in some quarters, on both sides of the aisle, as lacking black cred — an idea that’s now laughable. One lesson is that it’s a dicey business trying to define how anyone represents a particular group, or how voters of a group will respond to a particular candidate. Yes, the issue priorities of the black electorate, writ large, line up more closely with the Democrats’ platform. But the notion that an individual black voter can be written out of group membership on the basis of his vote is illogical and presumptuous. It turns an acknowledgment of a particular candidate’s edge into a suggestion that they somehow own the votes of a particular group, when they don’t.

Charlamagne’s show has become an important stop for Democratic presidential candidates. Biden’s appearance signals that he wants to court black voters, even if his comfort level likely got the better of him. Instead, he wound up policing their blackness.