During a town hall on CNN on Thursday night, Joseph R. Biden Jr. revived a debunked viral falsehood about President Trump’s much-criticized photo-op in Washington’s Lafayette Square in June.
“A president stands out there when people are peacefully protesting in front of the White House,” Mr. Biden, the Democratic presidential nominee, said. “He gets the military to go in for tear gas, move people physically, move them out of the way so he can walk across to a Protestant church and hold a Bible upside down.”
Video and photographs clearly show that the Bible wasn’t upside down, as fact checkers at PolitiFact and Snopes have noted. But that hasn’t stopped the claim from spreading on social media, an example of how speculation on the internet can morph into a zombie claim that refuses to die.
After law enforcement dispersed protesters in the square, Mr. Trump walked from the White House to a church damaged by fire and posed for photos while holding a Bible a little after 7 p.m.
A Twitter user speculated at 7:10 p.m. that evening that the Bible was upside down. Within minutes, the conjecture spread as fact, with the MSNBC host Joe Scarborough tweeting the claim to millions of followers. It then migrated to Facebook, where a post from a partisan website that has previously spread misleading information has been shared and engaged with more than 75,000 times.
Just three posts on Twitter making the claim — from Mr. Scarborough, the novelist Stephen King, and the musician John Legend — amassed more than 83,000 retweets and more than 340,000 likes.
Three months later, Mr. Biden repeated the false claim.