One More Failed Transcendental Argument

Abstract

In Self-Defeating Character of Skepticism, Douglas C. Long presents a transcendental argument against epistemological skepticism.' The argument has a distinctively Kantian flavor (though Long does not highlight this connection), in that it proceeds from the premise that I have self-knowledge and ends with the conclusion that I have perceptual knowledge of an objective, material subject of mental states. If the skeptic wishes to accept the transcendental argument's premise (as he seems to do), then he must reject his claim that I lack knowledge of all propositions concerning my physical nature, history and environment. The falsity of this skeptical claim is a condition for the possibility of self-knowledge, according to Long's transcendental argument. In this paper, I would like to see whether the argument is really workable. Long's target is the contemporary Cartesian skeptic whose challenge runs as follows. It is metaphysically possible that I am a brain in a vat who is massively mistaken about my own properties and those of the physical world, in virtue of the fact that my experiences are entirely computer-induced and unveridical. But no evidence or reasons are available which allow me to know that this possibility is not actual. Thus, I do not know any of the propositions about the physical world which are false according to the skeptical possibility. Long maintains that there is an epistemological difficulty in holding that I lack all ordinary perceptual knowledge (and thus lack perceptual knowledge of my body) while possessing the knowledge that I am the subject of various mental states (including experiences which may or may not be veridical and thoughts which may or may not bear true contents). Long's argument to establish the difficulty centers around the skeptic's Cartesian method for arriving at the knowledge that I am the subject of mental states in the absence of perceptual knowledge about the external world. The method involves an infer-