How do you make your mind up on controversial scientific questions? The debate around the origins of the Covid virus offers a nice lesson in how not to do it.

Earlier this week, it was revealed that the US Department of Energy currently believes that it’s more likely that SARS-CoV-2, the virus that causes Covid, was leaked from a lab in China than that it evolved naturally. Three days later, the director of the FBI announced that his agency concurred.

For a lot of participants in the debate, this settled it. The establishment, they argued, had been lying to us: we were told that only conspiracy theorists believed in a lab-leak Covid origin, but now that had been spectacularly overturned.