Russell is Buffett’s favorite philosopher, and these short essay collections show why. Russell wrote beautifully and thought with crystalline clarity. Immersing yourself in his ideas will sharpen your own skepticism. My favorite passage: “When a man tells you that he knows the exact truth about anything, you are safe in inferring that he is an inexact man…. It is an odd fact that subjective certainty is inversely proportional to objective certainty. The less reason a man has to suppose himself in the right, the more vehemently he asserts that there is no doubt whatever that he is exactly right.” Think about that the next time a financial adviser begins a sentence with the words “Studies have proven that….”

Sceptical Essays by Bertrand Russell. If I am to summarize the lesson from there, I would say: We should, as much as possible, avoid considering beliefs and propositions as definite and always remain open to the possibility of adjusting them based on new information.