Adam Kucharski

And actually, some analysis looking at US legal cases, obviously, they don't try and target these error rates, but you can sort of infer...

how people are valuing this, a lot of them seem to land between that kind of Blackstone and Franklin ratio of error.

But there is, of course, yes, the different evidence and how it makes its way into the courtroom, particularly some of the examples historically of kind of things like early probability.

And again, one of the challenges here is what one scholar I talked to called the weak evidence problem.

And I think a lot of how we navigate life is around evidence.

probabilities that are quite likely you know a lot of probability theory was originally developed around like dice games and things you know you can study and you can quantify but in legal cases we often have this weak evidence problem where you know someone ends up in some extremely bad looking situation from a guilt point of view and you're like well it's extremely unlikely this is just a coincidence but then if you think about it like well this person you know might just be a normal everyday person you know well it's extremely unlikely to

that they're guilty so you have these two extremely unlikely events and a lot of statistics just isn't equipped to handle that and so there's this notion it's called the prosecutor's fallacy where people say well this is the probability that that would all be a coincidence and therefore that's the probability they're innocent but of course you've got to weigh it against the fact that it's extremely unlikely they're guilty as well and we see this even in other areas so the the work we do dealing with like emerging health threats and

Pre-COVID, there were some studies, and actually we did a TV show, where you sort of say, oh, a pandemic could just be around the corner.

Or there was another study that the World Bank, I think, put it at 1%.

And you're like, well, what is that?

Was that a good prediction?

Was that a bad?

And it's these very unlikely events.

I think in legal cases, again, for that weak evidence problem, it's less about...

do we definitively work out with high probability which of those is true?

And it's more just we have to converge on the best explanation for what we've seen given those two possibilities.

And in reality, we may never have certainty about where we are.

And I think

It's something that kind of struck me, both thinking about that and then also thinking about a lot of people who have to plan for emergencies and very unlikely events, thinking a lot of the way we traditionally think about probability can very quickly lead us astray.

Because I think we're so used to having this idea, well, I can be 99% sure that this happened.