Kenny Easwaran, a philosopher at Texas A&M, recently published in the journal Nous this beautiful paper on Bayesian probabilities (hat tip: Brian Leiter). Among other things, Easwaran’s paper contains the best and most succinct explanation of the “paradox of the preface” we’ve ever read. Here it is (edited by us for clarity):

Dr. Truthlove … has just written an extensively researched book, and she believes every claim in the body of the book. However, she is also aware of the history of other books on the same subject, and knows that every single one of them has turned out to contain some false claims, despite the best efforts of their authors. Thus, one of the claims she makes, in the preface of the book, is to the effect that the body of this book too, like all the others, surely contains at least one false claim. She believes that too. She notices a problem. At least one of her beliefs is false. Either some claim from the body of the book (all of which she believes) is false, or else the claim from the preface (which she also believes) is. So she knows that she’s doing something that she hates–believing a false claim. At the same time, she notices a benefit. At least one of her beliefs is true! Either the claim from the preface is true, or all of the claims in the body of the book are true.

We shall have more things to say about this original paper in the days ahead …