Rather than production notes, today I’m just providing links to help explain Bayes’ Theorem. Bayes’ Theorem is a way of thinking about beliefs and evidence that allows one to have a more accurate map of reality in their heads. It is what Harry means when he says “Proof, Headmaster? There are only ever probabilities.” It helps us to best know how we know what we know.
The guide I find to be most understandable is Komponisto’s “Bayes’ Theorem Illustrated“. It is simply enough that you can grasp it without even engaging the equations. And as a bonus, it shows you how to grasp the correct answer to the Monty Hall problem.
Another guide is Eliezer’s own “An Intuitive Explanation of Bayes’ Theorem“. I think people are pretty much split on which of the two is better, so if one doesn’t work for you, try the other. They’re both good.
If you’re wondering “What Is Bayesianism, anyway?“, this link will give you the core tenants. It’s much shorter than either of the previous two, and may be the shortest summary possible. And as it notes of LessWrong (and by extension, this podcast) – “that’s basically what this site is for: to help us become good Bayesians.”