Kant and Skepticism

I. In this paper I want to sketch an account of the role of skepticism in Kant's critical philosophy.1 The critical philosophy set forth in the Critique of Pure Reason (henceforth: the Critique) grew from and responds to a complex set of philosophical concerns. Among these two of special importance are concerns to address skepticism and to develop a reformed metaphysics. This much is widely recognized. However, it is a fundamental thesis of this paper that those projects belong tightly together, in the following sense: The types of skepticism which really originated and motivate the critical philosophy are ones which target metaphysics; and what originated and motivates the critical philosophy's reform of metaphysics is above all the goal of enabling it to withstand skepticism. To amplify on the first point: When interpreting Kant, it is important to distinguish between the following three sorts of skepticism. First, there is "veil of perception" skepticism, or skepticism concerning the legitimacy of inferring from one's mental representations to the existence or character of a mind-external world (this is the very paradigm of skepticism for most Anglophone philosophers). "Veil of perception" skepticism does not specially target the claims of metaphysics (though these are among its targets). Second, there is Humean skepticism about concepts not derivable from sensible impressions and knowledge of propositions neither true in virtue of logical law nor known from experience (both of these forms of skepticism are exemplified in his treatment of causation). This sort of skepticism does have a special bearing on metaphysics due to the centrality of such putative concepts and knowledge to metaphysics. Third, there is Pyrrhonian skepticism, a skepticism which in the manner of the ancient Pyrrhonists motivates suspension of judgment by establishing a balance of