  There are two main traditions in epistemological skepticism. One tradition makes the claim that nobody ever knows or can know anything. This claim is sometimes named Cartesian skepticism (although Descartes argued against it) or Academic skepticism (despite other interpretations of skeptics in the ancient Academy). For lack of a better description, we can call it dogmatic skepticism, because such skeptics dogmatically assert a universal claim. In contrast, no such claim is made by Pyrrhonian skeptics. They also don’t deny any claim like this. They have so much doubt that they refrain from taking any position one way or the other on whether anyone does or does not or can or cannot know anything.