We explore consequences of the view that to know a proposition your rational credence in the proposition must exceed a certain threshold. In other words, to know something you must have evidence that makes rational a high credence in it. We relate such a threshold view to Dorr et al.’s (Philosophical Studies 170(2):277–287, 2014) argument against the principle they call fair coins: “If you know a coin won’t land tails, then you know it won’t be flipped.” They argue for rejecting fair coins because it leads to a pervasive skepticism about knowledge of the future. We argue that the threshold view of evidence and knowledge gives independent grounds to reject fair coins.
KeywordsEvidence Knowledge Thresholds Tolerance principle Probability Rational-belief Inference Epistemological skepticism about the future
Many thanks to Matti Eklund, Anandi Hattiangadi, Harvey Lederman, and an anonymous referee for this journal for their invaluable comments. This paper was presented at the Department of Philosophy, Uppsala University, Sweden. Spectre’s research was supported by the Israel Science Foundation (Grant No. 463/12). Rothschild’s research was supported by the UK Arts and Humanities Research Council (Grant Nos. AH/M009602/1 and AH/ N001877/1).
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