"It is dangerous to attach probability zero to anything other than a logical impossibility."

“Whatever way uncertainty is approached, probability is the only sound way to think about it.”

“Consider the case of a person who holds a view with probability 1. Then coherence says that it is no use having a debate with them because nothing will change their mind.”

“There are some things that you know to be true, and others that you know to be false; yet, despite this extensive knowledge that you have, there remain many things whose truth or falsity is not known to you. We say that you are uncertain about them. You are uncertain, to varying degrees, about everything in the future; much of the past is hidden from you; and there is a lot of the present about which you do not have full information. Uncertainty is everywhere and you cannot escape from it.”

“It is not merely a question of calculating with probabilities but also one of relating the ingredients of your probability statements to reality. You do not need to think only about p but also about the precise nature of E and K.”

“The grand assertion is that you must see the world through probability and that probability is the only guide you need.”

“Uncertainty is a personal matter; it is not the uncertainty but your uncertainty.”