Abstract
For a putative knower S and a proposition P , two types of skepticism can be distinguished, depending on the conclusions they draw: outer skepticism , which concludes that S does not know that P , and inner skepticism , which concludes that S does not know whether P . This paper begins by showing that outer skepticism has undesirable consequences because that S does not know that P presupposes P , and inner skepticism does not have this undesirable consequence since that S does not know whether P does not presuppose P . We indicate that the two types of skepticism aim to different loci of doubts: while outer skepticism doubts whether we can gain an epistemic warrant for the actuality, inner skepticism doubts whether we can gain epistemic identification of the actuality. It is further indicated that responses to skepticism from externalist theories, as well as from fallibilist internalist theories, can only respond to outer skepticism but not to inner skepticism.