In this paper I argue that Cartesian skepticism about the external world is self-defeating. The Cartesian skeptic holds that we are not justified in believing claims about the external world on the grounds that we cannot rule out the possibility of our being in a radical skeptical scenario. My argument against this position builds upon a critique of Wilson in Analysis, 72, 668–673. Wilson argues that the Cartesian’s skeptical reasoning commits him to mental state skepticism and that this undermines his (...) ability to claim that he is truly skeptical about the external world. I show that Wilson’s argument does not succeed. She is correct that the Cartesian is committed to mental state skepticism. However, she is mistaken in thinking that there is anything incoherent about combining the Cartesian position that one ought to doubt external world claims with doubt about whether one is in fact such a skeptic. I propose an alternative explanation as to why mental state skepticism proves to be the Cartesian’s undoing. I suggest that mental state skepticism leads to epistemic skepticism and that this undermines the Cartesian’s position that belief about the external world is unjustified. (shrink)

In this paper, I argue that arguments from skeptical hypotheses for external world skepticism derive their support from a skeptical argument from the distinction between appearance and reality. This skeptical argument from the appearance/reality distinction gives the external world skeptic her conclusion without appealing to skeptical hypotheses and without assuming that knowledge is closed under known entailments. If this is correct, then this skeptical argument from the appearance/reality distinction poses a new skeptical challenge that cannot be resolved by denying skeptical (...) hypotheses or knowledge closure. (shrink)

In a recent article, Wilson argues that Cartesian Scepticism leads to a vicious regress that can only be stopped by rejecting Cartesian Scepticism. If she is right, Wilson has solved one of philosophy's enduring problems. However, her regress is irrelevant to Cartesian Scepticism. This is evident once the proposition that we should have doubts, the person who has doubts, and the person who thinks that we should have doubts are carefully distinguished.

There is a controversy, within social epistemology, over how to handle disagreement among epistemic peers. Call this the problem of peer disagreement. There is a solution, i.e. the equal-weight view, which says that disagreement among epistemic peers is a reason for each peer to lower the credence they place in their respective positions. However, this solution is susceptible to a serious challenge. Call it the merely modal peers challenge. Throughout parts of modal space, which resemble the actual world almost completely, (...) there are hordes of epistemic peers, who disagree with almost any arbitrarily chosen belief had by residents of the actual world. Further, the mere modality of these peers is not itself an epistemic difference-maker. Thus, on the equal-weight view, we should significantly lower the credence we place in most of our beliefs. Surely, this is seriously mistaken. Thus, there are serious considerations that cut against the equal-weight view. (shrink)

This dissertation is on infinite regress arguments in philosophy. Its main goals are to explain what such arguments from many distinct philosophical debates have in common, and to provide guidelines for using and evaluating them. Two theories are reviewed: the Paradox Theory and the Failure Theory. According to the Paradox Theory, infinite regress arguments can be used to refute an existentially or universally quantified statement (e.g. to refute the statement that at least one discussion is settled, or the statement that (...) discussions are settled only if there is an agreed-upon criterion to settle them). According to the Failure Theory, infinite regress arguments can be used to demonstrate that a certain solution fails to solve an existentially or universally quantified problem (e.g. to demonstrate that a certain solution fails to settle all discussions, or that it fails to settle even one discussion). In the literature, the Paradox Theory is fairly well-developed, and this dissertation provides the Failure Theory with the same tools. (shrink)

Jessica Wilson has recently offered a more sophisticated version of the self-defeat objection to Cartesian scepicism. She argues that the assertion of Cartesian scepticism results in an unstable vicious regress. The way out of the regress is to not engage with the Cartesian sceptic at all, to stop the regress before it starts, at the warranted assertion that the external world exists. We offer three reasons why this objection fails: first, the sceptic need not accept Wilson’s characterization of the sceptical (...) thesis and thus need not start her regress; second, even if she did commit to the regress, it would not undermine scepticism in the way Wilson envisages; and third, the appeal to mental state scepticism which is necessary to generate the second and subsequent steps in the regress is not justified. (shrink)