On Sept. 24, 2015, Geoffrey Pyatt, then the U.S. ambassador to Ukraine, spoke in Odessa about the scourge of corruption. It was about a year and a half after what is sometimes called the Revolution of Dignity, when Ukrainians overthrew the kleptocratic, Russian-aligned regime of Viktor Yanukovych. The country was trying to move in a more liberal, European direction. Corruption, said Pyatt, threatened to hold the new Ukraine back.

Pyatt called out the office of Viktor Shokin, then the prosecutor general of Ukraine. “Corrupt actors within the prosecutor general’s office are making things worse by openly and aggressively undermining reform,” he said. Pyatt specifically lambasted Shokin’s office for subverting a British case against a man named Mykola Zlochevsky, Yanukovych’s former ecology minister.

In 2014, as part of a money-laundering investigation, British authorities froze $23 million Zlochevsky had in London. They requested supporting documentation from Shokin’s office. Instead, it intervened on Zlochevsky’s behalf. “As a result, the money was freed by the U.K. court and shortly thereafter the money was moved to Cyprus,” said Pyatt.

“Shokin was seen as a single point of failure clogging up the system and blocking corruption cases,” a former official in Barack Obama’s administration told me. Vice President Joe Biden eventually took the lead in calling for Shokin’s ouster.

As all this was happening, Biden’s son, Hunter, sat on the board of Burisma Holdings, a natural gas company that Zlochevsky co-founded, at some points earning $50,000 a month. Zlochevsky might have thought he could ingratiate himself with the Obama administration by buying an association with the vice president. All available evidence suggests he was wrong.

Turning this history on its head, President Donald Trump has accused Joe Biden of coercing Ukraine to jettison Shokin in order to protect Hunter. He has pressured Ukraine’s current president to open an investigation into the Bidens, which would make Trump’s charges seem more credible. As the president faces impeachment, his surrogates are parroting his attack on Biden, and his campaign is reportedly spending a staggering $10 million on an ad to amplify the smear.

Journalists, perhaps seeking to appear balanced, have sometimes described Trump’s claims about Biden as “unsubstantiated” or “unsupported.” That is misleading, because it suggests more muddiness in the factual record than actually exists. Trump isn’t making unproven charges against Biden. He is blatantly lying about him. He and his defenders are spreading a conspiracy theory that is the precise opposite of the truth.

Like most effective conspiracy theories, this one is built around a speck of something real. Hunter Biden’s place on Burisma’s board was untoward, even if it’s preposterous for Trump to complain about nepotistic corruption. Biden’s son doesn’t seem to have broken any laws, but the way he traded on his name was still sleazy.

Joe Biden appears to have been uncomfortable with his son’s involvement with Burisma; in a New Yorker profile, Hunter recalled his father saying, “I hope you know what you are doing.” Hunter said they never spoke further about the issue; Biden has made a point of not talking to his son about his business dealings.

It’s not hard to imagine why Biden didn’t press Hunter. The Biden boys and their father had been through hell together. Hunter has said his first memory was waking up in the hospital next to his older brother, Beau, after the car crash that killed their mother and baby sister. He grew up to be a troubled man, his life pockmarked by addiction and failure.

Beau died of brain cancer a few months before Biden traveled to Ukraine to push the government to crack down on corruption. It’s not shocking that, at a moment when his family was consumed by grief, Biden wasn’t inclined to confront his surviving son.

But even if you’re not inclined to empathize with Biden — even if you assume the worst about him — Trump’s conspiracy theory makes no sense. To believe it, you’d have to first believe that the foreign affairs apparatus of the Obama administration was willing to put its credibility on the line in service of the black sheep of the Biden family. After all, Joe Biden wasn’t freelancing in Ukraine; he was carrying out White House policy.

Further, if the Trump administration truly believes that Obama’s Ukraine policy was crooked, one might ask why it has Pyatt, who helped accomplish that policy, representing America as ambassador to Greece.

Most important, getting rid of Shokin made an investigation of Burisma more likely, not less. “He didn’t want to investigate Burisma,” the Ukrainian anti-corruption activist Daria Kaleniuk told The Washington Post. “Shokin was fired not because he wanted to do that investigation, but quite to the contrary, because he failed that investigation.”

However bad the optics around Hunter Biden, Joe Biden was not serving his son’s interests. If anything, they were working at cross-purposes.

As I’ve written multiple times, I don’t want Biden to be the Democratic nominee. There’s much in his legislative record that troubles me, and I don’t think he’s as electable as his champions claim. In some ways, my preferred political outcome would be advanced if Trump’s Ukraine scandal ends up tarring Biden as well.

But Trump’s weaponized disinformation is corrosive to democracy no matter whom it targets. Like many authoritarians, he depends on getting people to accept a big lie or to give up on the idea of truth altogether. If he succeeds in defaming Biden today, he’ll be even more audacious in using the same strategy against anyone else who threatens him. What’s at stake isn’t just Biden’s political future. It’s how much Trump can erode the political salience of reality, and how much the media helps him.

Michelle Goldberg

Michelle Goldberg is an Op-Ed columnist for The New York Times.