Abstract

In everyday life, we think of skepticism as the position of a stubborn person who has higher epistemic standards than others. Hence, the skeptic is someone who defends extravagant ideas. Some skeptics may deny that climate change is real, while others claim that the first moon landing did not take place. Contemporary philosophers think of skepticism in a different way. In their view, skepticism is the conclusion of a paradoxical argument about epistemic statuses like knowledge and reasons. A paradoxical argument is a logically valid argument that, starting from seemingly plausible premises, reaches an absurd conclusion. We introduce two skeptical arguments. The regress argument purports to show that we lack reasons to believe any claim whatsoever because the search for those reasons inevitably leads to an infinite regress. The underdetermination argument seeks to prove that we lack reasons to believe that there are chairs, trees, other people, and so on; it supports that conclusion by citing skeptical hypotheses, including the idea that we might be dreaming (Descartes 1641) or the suggestion that we could be brains in a vat connected to a supercomputer that mimics the pattern of neural activity that would be produced if we were perceiving external objects (Putnam 1981).