Knowledge and Certainty

Abstract

Are any of us ever certain of anything? In one sense, we clearly are. Being certain often means nothing more than having a confident belief, and there is no question that we are often confident about what we believe. This is a very weak and uninteresting sense of certainty, however, and not the one philosophers have usually had in mind when they asked whether we are ever certain. This stronger, philosopher’s sense is often referred to as ‘absolute certainty’. Unfortunately, it is not very clear what this term means or even, I think, whether ‘certainty’ is ever used in this sense in ordinary language. Ordinary speakers might use the term in the weaker sense to mean firm belief while the stronger sense is a technical notion of philosophers. Since one of the issues I wish to deal with here is whether philosophers have been correct in claiming that we are sometimes absolutely certain (a doctrine I will call ‘infallibilism’), we must attempt to clarify the philosopher’s use of the term. The question whether this is also the ordinary sense of ‘certain’ can be left to one side. How then might we clarify ‘absolute certainty’?