Benjamin Franklin was wrong, or at least premature, when he wrote in 1789 that nothing is certain in this world “except death and taxes.”

Were he writing today, he would have to add to this sacred duo another entry — that it’s also certain that the theory that COVID-19 originated in a Chinese lab will persist, despite the absence of any evidence to support it.

As I’ve written before, this fact-free claim periodically receives a shot of life-extending plasma from credulous news organizations, congressional Republicans, and former and current Trump acolytes.

On Saturday, the lab-leak claim got another dose of plasma. This was the Central Intelligence Agency’s issuance of its purported “assessment” that a lab leak was more likely than zoonosis as the pandemic’s origin.

The agency issued its statement at the behest of John Ratcliffe, who was confirmed Friday as Donald Trump’s choice for director of the CIA.

The CIA’s assessment rocketed around the news and political worlds, spurring more heavy breathing from partisans who have long deployed the claim as part of a geopolitical contest with China.

The headline takeaway in many news articles was that the “CIA Now Favors Lab Leak Theory on Origins of Covid-19” (Wall Street Journal and New York Times).

Some also gave various degrees of prominence to the CIA’s admission that it made its judgment with “low confidence.” My colleagues at The Times placed that caveat in the headline of our publication of an Associated Press dispatch on the CIA statement.

Partisan commentary on the CIA statement ignored that caveat.

“Now, the most important thing is to make China pay for unleashing a plague on the world,” Sen. Tom Cotton (R-Ark.), a veteran advocate of the lab-leak theory, told Politico.

In an interview with the conservative news site Breitbart on Friday, the day of his confirmation, Ratcliffe made no secret of his intention to pursue the issue as an issue for national security.

“One of the things that I’ve talked about a lot is addressing the threat from China on a number of fronts,” he said, “and that goes back to why a million Americans died and why the Central Intelligence Agency has been sitting on the sidelines for five years in not making an assessment about the origins of COVID.”

Among the political warriors who seized promptly on the CIA statement was Jonathan Turley, a law professor at George Washington University who has emerged as a leading critic of the left. In an article posted Monday on his personal web page, Turley originally wrote that the CIA statement “details how it views the lab theory as the most likely explanation for the virus.”

Therefore, it’s important to take a close look at what the CIA said, how it might have differed from its previous judgments, and just what it means to issue a conclusion with “low confidence.”

“CIA assesses with low confidence that a research-related origin of the COVID-19 pandemic is more likely than a natural origin based on the available body of reporting,” read the statement by a CIA spokesman. The statement added that the agency would keep evaluating “any available credible new intelligence reporting or open-source information that could change CIA’s assessment.”

To begin with, there were no “details” in the CIA statement explaining the basis for its conclusion. The CIA didn’t offer any evidence or explain what prompted its assessment, or reassessment.

It’s unclear even how new its assessment is. In June 2023, at then-President Biden’s directive, the Office of the Director of National Intelligence released a declassified report summarizing the conclusions of the U.S. intelligence community. The office oversees the work of 18 intelligence agencies, including the CIA.

The report stated that five intelligence agencies assessed that “natural exposure to an infected animal” caused the pandemic; two — the FBI and the Department of Energy — came down on the lab-leak side; and the CIA and another unnamed agency were “unable to determine the precise origin” of the pandemic. It didn’t give assessments by other agencies.

The ODNI report left lab-leak proponents crestfallen. They had been certain that it would validate their position; instead, it specifically refuted several core claims made by the lab-leak camp.

Then there’s the “low confidence” qualification. This is not a casual judgment about information, but a term of art with a specific meaning in the intelligence community.

According to a definition published in 2017 by ODNI, it “generally means that the information’s credibility and/or plausibility is uncertain, that the information is too fragmented or poorly corroborated to make solid analytical inferences, or that reliability of the sources is questionable.”

To put it in plain language, the CIA “assessment” is based, at best, on unreliable sources and that it’s too uncertain and unverified to “make solid analytical inferences.” That hasn’t stopped people like Ratcliffe and Cotton from aggressively coming to their own conclusions and making threats against another country.

Turley, for his part, added a paragraph to his original post acknowledging that the CIA considered the evidence for a lab leak “fragmented and fluid.” He didn’t tell me when he made the change, but the link to the definition of “low confidence” he embedded in his post was one that I had posted online and referred him to.

Turley told me by email that his goal had not been to argue that “one theory is clearly correct,” but that “there was a legitimate debate on the issue that was being suppressed by the attacks and the coverage…. The issue is not which theory is correct but the fact that either could be true and, as shown by other reports, the lab theory is actually favored by some agencies and offices today.”

Is that so, however?

Let’s be clear about something: No scientifically valid evidence has ever been produced to support the theory that the COVID virus escaped from a Chinese laboratory. All that exists is conjecture, innuendo and speculation, most of it based on the circumstance that the first COVID cases were identified at a wildlife market in Wuhan, miles from a government virology lab.

But no evidence has ever emerged of an outbreak in that lab or its vicinity, while copious epidemiological evidence exists for its outbreak at the Huanan market, where people bought and sold critters known to be susceptible to COVID.

If there were a paper published in a peer-reviewed journal setting forth evidence for a lab leak, it would be prominently cited in every news article about the origins debate. There doesn’t appear to be any.

John P. Moore, a professor of microbiology and immunology at Weill Cornell Medical College who assiduously tracks technical papers about COVID for a weekly digest, told me he “does not know of any such papers — only speculative articles.”

The Chinese government has been accused, mostly by the lab-leak camp, of suppressing evidence of the role of the Wuhan lab out of embarrassment or fear of international repercussions. But that’s highly misleading. The truth is that China is no happier about evidence that the pandemic originated in one of its wildlife markets. It has also been criticized by the World Health Organization for a lack of transparency.

The Chinese government has long promised to regulate the wildlife trade within its borders, but its efforts have been spotty, with many markets continuing to operate. After the initial outbreak of COVID in Wuhan, the government shut down the Wuhan market, where 30 species of wild animals were part of the inventory and some 10,000 visitors a day strolled its alleyways.

The shutdown complicated efforts to pinpoint the outbreak’s origin, but research conducted before the shutdown documented the presence of COVID-infected animals on the premises.

The uncritical retailing of the CIA assessment underscores the perils of scientific misinformation and disinformation for public health. The Trump administration’s evidence-free focus on the Chinese laboratories ranks as anti-science propaganda.

As 41 biologists, immunologists, virologists and physicians observed in August in the Journal of Virology, the unfounded lab-leak hypothesis “stokes the flames of an anti-science, conspiracy-driven agenda, which targets science and scientists even beyond those investigating the origins of SARS-CoV-2,” the virus that causes COVID.

“The inevitable outcome is an undermining of the broader missions of science and public health and the misdirecting of resources and effort,” they wrote. “The consequence is to leave the world more vulnerable to future pandemics, as well as current infectious disease threats.”

Their warning could not have been more stark.