Can the skepticism debate be resolved?

External world skeptics are typically opposed to admitting as evidence anything that goes beyond the purely phenomenal, and equally typically, they disown the use of rules of inference that might enable one to move from premises about the phenomenal alone to a conclusion about the external world. This seems to bar any a posteriori resolution of the skepticism debate. This paper argues that the situation is not quite so hopeless, and that an a posteriori resolution of the debate becomes possible once it is recognized that the skeptic holds overly defensive and ill-motivated positions vis-à-vis both evidence and inference, and that more reasonable ones are available. In stating these more reasonable positions, as well as in showing how they make possible an a posteriori resolution of the skepticism debate, the paper draws on the machinery of Bayesian epistemology. We should be careful to get out of an experience only the wisdom that is in it—and stop there; lest we be like the cat that sits down on a hot stove-lid. She will never sit down on a hot stove-lid again—and that is well; but also she will never sit down on a cold one anymore. Mark Twain, Following the Equator Few nowadays believe that external world skepticism (henceforth simply “skepticism”) can be rejected on a priori grounds. But it seems that there can hardly be more hope for a successful a posteriori resolution of the skepticism debate. Skeptics are typically opposed to admitting as evidence anything that goes beyond the purely phenomenal; and, equally typically, they disown the use of inferential principles that might enable one to move from premises about the phenomenal alone to a conclusion about the external world. Not all non-skeptics may find this troublesome, as it seems that the aforementioned facts need not bar an a posteriori argument against skepticism. Supposing a less restrictive conception of evidence than the skeptic’s, or stronger rules of inference than she is willing to countenance, may enable one to argue on empirical grounds for the external world hypothesis. Such an argument may leave the skeptic cold, and therefore may not bring any nearer an a posteriori resolution of the skepticism debate, which I understand to require that the debate be settled in a way that is 1One of the referees expressed concern about whether any good definition of “external world skepticism” exists. While the referee may well be right that the hypotheses standardly advanced in support of external world skepticism are, from a metaphysical perspective, a mixed lot, one could argue that they can still be characterized in a unified way in (the broadly epistemic) terms of empirical equivalence and underdetermination, by means of which we can in turn characterize external world skepticism; see, e.g., Vogel [2004] and Douven [2007]. However, here I will not do so and simply assume the mainstream to be right in supposing external world skepticism to be a well-defined philosophical position.