How to get the most out of realizing you are wrong by using Bayes' Theorem to update your beliefs

You don't treat all of your beliefs equally.

For some, you see them as either true or false, correct or incorrect. For others, you see them as probabilities, chances – odds. In one world, you live in certainty, in the other, uncertainty.

In this episode we explore why you gladly update some beliefs yet refuse to update others.


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In this episode you will learn from two experts in reasoning how to apply a rule from the 1700s called Bayes' Theorem not only to numbers you can plug into formulas, but also to the beliefs you carry around in order to make sense of the world.

julia-galef-headshotJulia Galef is the president and co-founder of the Center for Applied Rationality, a non-profit organization that training people and organization to make better decisions. She is also the host of the Rationally Speaking Podcast and has written for Slate, Science, Scientific American, and Popular Science.

NeilAMansonNeil A. Manson is a philosopher and professor who teaches at the University of Mississippi. He teaches logic, philosophy, religion, philosophy of science, and medical ethics. His research concerns the design argument, and he assembled an anthology on the topic titled: God and Design: The Teleological Argument and Modern Science.

In the show, Manson explains the math side of Bayes' Theorem, and Galef tells us how Bayes' Theorem makes it possible to see all of your beliefs as being in "grayscale," as neither black nor white, neither 0 nor 100 percent, but always somewhere in between, as a shade of gray reflecting your confidence in just how wrong you might be given the evidence at hand.

In every episode, after I read a bit of self delusion news, I taste a cookie baked from a recipe sent in by a listener/reader. That listener/reader wins a signed copy of my new book, "You Are Now Less Dumb," and I post the recipe on the YANSS Pinterest page. This episode's winner is Andreas von Normann who submitted a recipe for Navette Provencale cookies. Send your own recipes to david {at}

Links and Sources


Previous Episodes

Boing Boing Podcasts

Cookie Recipes

Understanding Bayes' Theorem

An Intuitive Explanation of Bayes' Theorem by Luke Muehlhauser

Rationally Speaking

Center for Applied Rationality

Julia Galef

Neil A. Manson

Image Source: Popular Science Monthly Public Domain – Wikimedia Commons