Descartes's "Demon"

David Kelley’s “The Evidence of the Senses”, originally his PhD dissertation and since reworked into a book available at Amazon, is the complete examination of the philosophical issues involving the senses.   I long ago made a thread to give a taste of what is in it at Notes on “The Evidence of the Senses”.  

In the last chapter Kelley puts forward three principles of justified perceptual judgement and treats the case of when one can make a justified error of perceptual judgement, that a Not-F is F.  Such a possibility does not undermine confidence in the senses in general, because this conclusion is itself the product of knowledge gained through perception.  A general skepticism is self-refuting as logical conclusion and so can only be held as an arbitrary a priori premise.  Since an arbitrary a priori premise follows from no evidence, it can be dismissed without evidence.