Knowledge and Certainty

  • Robert G. Meyers
Part of the Philosophical Studies Series book series (PSSP, volume 38)


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’?


Modal Logic Epistemic Condition Ordinary Language Logical Possibility Absolute Certainty 
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  1. 5.
    It is doubtful that this would help to convince others, especially a skeptic. To convince them, we might offer a demonstrative argument to show that we have knowledge, appealing to premisses they would accept. This amounts to showing inferentially that we have knowledge and so serves to confirm the putative intuition that we do. In chapter 2, section 3, I will argue that Descartes’ “Cogito, ergo sum” can be understood in this way. See also Wolfson, 1969, I, pp. 174–175, who interprets Spinoza’s ontological argument to be an attempt to confirm what Spinoza took to be an intuition that God exists.Google Scholar
  2. 6.
    Moore (1959b, p. 228): “if I were to assert now ‘It is possible that I am not standing up’ I should naturally be understood to be asserting that I do not know for certain that I am.”Google Scholar

Copyright information

© Kluwer Academic Publishers 1988

Authors and Affiliations

  • Robert G. Meyers
    • 1
  1. 1.Department of PhilosophySUNY at AlbanyUSA

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