I have a question about Cartesian skepticism. One of the premises of the argument is something to the effect of:
(1) I don't know that I'm not dreaming.
My question is: What justifies this proposition? My intuition is that the evidence for (1) cannot possibly be empirical; for the upshot of the skeptical argument is precisely that all empirical claims are dubious. (Maybe it's helpful to rephrase (1) as "It's possible that I'm dreaming," if that is legitimate.)
Descartes' arguments suggest that he believe d that, for any empirical test that you might devise to determine whether you are awake or dreaming, it might be the case that anytime you appeal to putative test results you have merely dreamed that you have performed the test. So, I think you are right that, whatever arguments Descartes developed to respond to his own skeptical doubts, those arguments were not straightforward empirical ones appealing to things like tests of that sort. Similarly, when he addressed issues related to skepticism Descartes' eighteenth-century successor developed a style of non-empirical transcendental argumentation. Another way to approach the issues that your question engages is to focus not on Descartes' specific argument but rather on the general skeptical doubt that it can raise so hauntingly. The contemporary philosophy Barry Stroud puts this doubt this way in his wonderful book, _The Significance of Philosophical Skepticism:"Could not the external world be completely...