One of the things being litigated in this presidential campaign is whether the crowds at rallies are even real.

At a Detroit aircraft hangar last week, Democratic presidential nominee Vice President Kamala Harris and her running mate, Minnesota Gov. Tim Walz, stepped off Air Force Two greeted by thousands of supporters. NPR’s Tamara Keith was there to see it.

There were 15,000 people at the rally, according to the Harris campaign. Photos and videos by attendees and media organizations captured the crowd from many angles.

But former President Donald Trump and his supporters have falsely claimed the crowd seen in a photo of the rally in front of Harris’ plane was a product of generative artificial intelligence. On Sunday, Trump made the nonsensical claim that the very real crowd at the event was a fabrication..

“Has anyone noticed that Kamala CHEATED at the airport?” reads one of his posts on Truth Social “There was nobody at the plane, and she “A.I.’d” it, and showed a massive “crowd” of so-called followers, BUT THEY DIDN’T EXIST!”

When a reporter asked him Wednesday about why he made the claim given that it was proven false, Trump did not acknowledge his claim had been untrue. “Well I can’t say what was there, who was there,” responded Trump in an exchange that was televised by Fox News. “I can tell you about ours, we have the biggest crowds ever in the history of politics.”

The Trump campaign did not respond to a request for comment.

The Harris campaign confirmed to NPR that the photo in question was taken by a campaign staffer and was not modified by AI.

The ‘Liar’s Dividend’

The refusal to accept basic, verifiable facts has some observers concerned about a repeat of 2020 false claims of a stolen election if former President Donald Trump loses.

Scholars who study deepfakes have pointed out that the existence of the technology means people can try to claim authentic videos and photos are fake. Back in 2018, law professors Robert Chesney and Danielle Citron even coined a term for this phenomenon, calling it, “The Liar’s Dividend.”

Hany Farid, a professor at University of California, Berkeley who specializes in forensic images, ran the Harris campaign rally photo through two computer models to see if there were any signs of patterns consistent with generative artificial intelligence or manipulation and found none.

“This is an example where just the mere existence of deepfakes and generative AI allows people to deny reality,” Farid said. “You don’t like the fact that Harris Walz had such a big crowd? No problem. Photos are fake. Videos are fake. Everything’s fake.”

Farid said such claims muddy the waters, which “is a pretty good strategy if you want to create doubt among the electorate.”

Sen. Bernie Sanders, who’s independent but caucuses with Democrats, said in a statement on Tuesday that Trump’s false comments about the Harris rally are a sign he is laying the groundwork to claim the election was stolen if he loses.

“If you can convince your supporters that thousands of people who attended a televised rally do not exist, it will not be hard to convince them that the election returns in Pennsylvania, Michigan, and elsewhere are ‘fake’ and ‘fraudulent,’” Sanders wrote.

The rally photo looked unusual, Farid acknowledged, due to the lighting and compression. But the features that social media users pointed to as evidence that the photo was inauthentic were not accurate, Farid said. The distorted hands some social media posts pointed out were a product of a low resolution version of the photo circulating online.

Farid said he is troubled by the continued debate over the veracity of the photo online given the lack of evidence that it is anything but authentic, and the fact that there are abundant photos and videos showing the size of the crowd at the rally.

“This is a photo of an event in one city on one day,” Farid said. “I mean, what hope do we have to actually tackle complex problems in society if we can’t agree on this?”

Democracy without shared facts

It’s a problem for citizens of a democracy to have a blurred understanding of what is real and staged, said University of California, Los Angeles law professor, Rick Hasen during a panel discussion hosted by the Wikimedia Foundation on Monday.

“If voters tend to disbelieve anything they see, and think that whatever they see might be faked, then they’re going to distrust their own instincts as to what the truth is to be able to make competent decisions,” Hasen said.

In response to one of Trump’s false posts about the rally photo, the Harris campaign posted a video from the Detroit rally with the caption, “In case you forgot @realdonaldtrump: This is what a rally in a swing state looks like.”

While not in the same league as claiming a crowd was fabricated, the Harris campaign has made its own social media posts about a Trump’s rally that gave an inaccurate impression. As Trump held in Atlanta earlier this month, the Harris campaign highlighted what looked like a larger crowd for Harris days earlier at the same venue. But the images of Trump’s crowd were taken when the venue was still filling up before all seats were taken.

Trump’s false claim that Harris “cheated” with a fake crowd likely resonated with his supporters who also believe the false claim that Democrats stole the 2020 election, said Mert Bayar, a postdoctoral fellow at the University of Washington’s Center for an Informed Public.

“It’s part of a belief system not trusting the other party,” Bayar said.

Furthermore, as the presidential race has shifted with Harris and Walz at the top of the Democratic ticket, many Trump supporters are looking for evidence that their candidate still has the upper hand.

“The vast majority of misinformation is offered as a service for people to maintain their beliefs in face of overwhelming evidence to the contrary,” wrote Mike Caulfield, who has studied how rumors spread, in his newsletter, The End(s) of Argument, about the false claims about Harris’ rally image.

As Caulfield warns, it’s difficult for people to make sense of reality in an honest way when we are “flooded with cheap fabricated or misrepresented evidence” as happened in the aftermath of the 2020 election and is happening again during this campaign season.