Steven Pinker: The inside story of my Covid ‘bio bet’

Betting men

Sir: The bet between Martin Rees and me that Matt Ridley recounts pits two kinds of scruples of disinterested rationality against each other (‘Wuhan wager’, 7 December). One is the scientific ethos that calls for factoring in all relevant information in updating one’s degree of credence in a hypothesis. The other is the logic of the epistemological tool of betting, which demands an agreed-upon fixed criterion and deadline for resolving the bet. My degree of credence has been influenced by Matt and Alina Chan for the lab leak hypothesis, but also by counter-arguments from Peter Miller for the zoonotic theory.

When Martin and I joined the bet, neither of us thought that the ensuing train of events would be so causally ambiguous, so we did not anticipate that we would need to lay out rigorous criteria for resolving it. As Covid-19 unfolded, we quickly agreed that a lab origin would mean that Martin won. We also agreed that the early ‘consensus’ about a zoonotic origin was not convincing enough to settle the bet. We kicked the can down the road until the prediction site Metaculus set up a forecast for the origin of Sars-CoV-2 together with a criterion and deadline for resolving it. The two of us agreed that this satisfied the logic of betting and agreed to use it to resolve our own too-vague-to-settle bet. But as Matt points out, my winning the bet does not resolve the scientific question.

Steven Pinker

Cambridge, Massachusetts