Closure On Skepticism

Journal of Philosophy 107 (5):243-256 (2010)
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It is received wisdom that the skeptic has a devastating line of argument in the following. You probably think, he says, that you know that you have hands. But if you knew that you had hands, then you would also know that you were not a brain in a vat, a brain suspended in fluid with electrodes feeding you perfectly coordinated impressions that are generated by a supercomputer, of a world that looks and moves just like this one. You would know you weren’t in this state if you knew you had hands, since having hands implies you are no brain in a vat. You obviously don’t know you’re not a brain in a vat, though—you have no evidence that would distinguish that state from the normal one you think you’re in. Therefore, by modus tollens, you don’t know you have hands. At least, the skeptic has a devastating argument, it is thought, if we grant him closure of knowledge under known implication, which many of us are inclined to do: roughly, if you know p, and you know that p implies q, then you know q

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Sherrilyn Roush
University of California, Los Angeles

Citations of this work

Saving Sensitivity.Brett Topey - 2022 - Philosophical Quarterly 72 (1):177-196.
Questions, topics and restricted closure.Peter Hawke - 2016 - Philosophical Studies 173 (10):2759-2784.
A Problem for the Closure Argument.Philip Atkins & Ian Nance - 2014 - International Journal for the Study of Skepticism 4 (1):36-49.

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Knowledge and Its Limits.Timothy Williamson - 2000 - Philosophy 76 (297):460-464.
Epistemic operators.Fred I. Dretske - 1970 - Journal of Philosophy 67 (24):1007-1023.
Knowledge and the Flow of Information.Fred I. Dretske - 1981 - Revue Philosophique de la France Et de l'Etranger 175 (1):69-70.
Conclusive reasons.Fred I. Dretske - 1971 - Australasian Journal of Philosophy 49 (1):1-22.

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