Kamala Harris didn’t comport herself with confidence or conviction in the last debate. Her shaky performance on Wednesday (July 31) added to the rational arguments about why she shouldn’t be the Democratic nominee for president — her somersaults on busing, her record as California’s attorney general, her inability to parry shots from her opponents.

But there is one peculiar argument making the rounds about the U.S. senator from California that shouldn’t be a consideration — shouldn’t even get serious attention: that Harris is not really an authentic black American, according to liberal activist Antonio Moore, leader of a small movement calling itself American Descendants of Slavery.

Harris’ parents are both immigrants: her father from Jamaica, her mother from India. Only those whose ancestors were enslaved — in the United States, presumably — can be counted as legitimate American blacks, Moore and his followers say. (Never mind that Jamaica also had a history of slavery under British rule.)

That’s absurd. If we took that argument seriously, it would discount Barack Obama, the nation’s first black president, a man in whom the vast majority of black voters invest justifiable pride. After all, his mother was a white American, and his father was a black Kenyan.

Indeed, there was a tiny minority of black commentators and mischief-makers who questioned Obama’s “blackness” as his presidential campaign began to draw notice. In 2007, black cultural critic Stanley Crouch wrote: “When black Americans refer to Obama as ‘one of us,’ I do not know what they are talking about. He has not lived the life of a black American.” Happily, that sort of critique died away pretty quickly as Obama soared to the top of the Democratic field, drawing tens of thousands of enthusiastic supporters, black, white and brown, at his rallies.

Drawing that sort of invidious distinction is even more dangerous now than it was then because President Donald J. Trump and his allies use it to their advantage. Remember all those hacked emails from the Democratic National Committee, robotically repeated by the news media? Those emails, likely part of the Russian effort to sow dissent among American voters, helped amp up distrust among Bernie Sanders’ supporters, many of whom then refused to vote for Hillary Clinton. So, taking a page from the Vladimir Putin playbook, Donald Trump Jr. last month shared a tweet from a right-wing media personality disputing Harris’ identification as a black American.

Harris has every right to call herself a black American because she is one. (I find the term African American unwieldy and often inaccurate. A Nigerian immigrant is an African American.) As she has said, she was bused to a predominantly white school as a child to aid integration. And if she were not a prominent politician, she could easily be stopped and harassed by bigoted police officers or followed around in a shop by clerks who suspect her of shoplifting. That’s all part of the black experience in America — one in which she has shared.

Regardless of the particulars of ancestry, one thing that binds all black Americans together is our vulnerability to the prejudices that whites hold toward those with darker skin. Black Americans display a range of political preferences, religious beliefs, sexual practices, cultural affinities, and practical capabilities, but we are all subject to stereotyping by white employers, police officers, and retail security guards who don’t bother to ask whether our ancestors were enslaved.

Just ask South Carolina Republican Sen. Tim Scott, who happens to be black. Deeply conservative and popular with his white constituents, Scott has nevertheless stood on the Senate floor to explain to his white colleagues — many of whom are dismissive of the notion that racism still exists — that he has been stopped by police officers many times for the crime of driving while black. Obama has spoken of being passed over by cab drivers reluctant to pick up a black man. And Harris has undoubtedly had her own share of such experiences.

In the 2020 campaign, Trumpists will clearly again use the tactic of attempting to sow division on the left — and they may well again have Russia’s help to do it. Let’s not do their dirty work for them.