Knowledge and Skepticism

11. Anti-Individualism, Self-Knowledge, and Why Skepticism Cannot Be Cartesian

11 Anti-Individualism, Self-Knowledge, and Why Skepticism Cannot Be Cartesian Leora Weitzman Anti-individualism is often said to be at odds with the Cartesian view of the mind that grounds external-world skepticism. For according to the Cartesian view, it is coherent to doubt whether any of one’s thoughts correspond to external objects, whereas anti-individualism says it is a conceptual truth that without objects external to an individual, that individual’s purported thoughts would have no content at all.1 But what is external to an individual? Anti-individualist thought experiments often depict the individual as a physical creature bounded by its skin (or skull),2 but this boundary cannot simply be assumed in an attempt to deploy anti-individualism against a serious Cartesian skeptic, since the existence of skin, skull, or anything physical at all is part of what’s in question. A well-known argument, originally due to McKinsey, seems to hold out the possibility of proving to skeptics that there are physical things (though that is not the lesson McKinsey draws from it). Such a proof would both reply to physical-object skepticism and restore the credibility of a physical boundary of the self. Much has been written about the McKinsey argument , but two things have been missing from the discussion. One is a thorough assessment of the extent to which the anti-individualism it relies on can be made compelling for the skeptic. Section 1 will undertake this task. The second missing element, taken up in section 2, is the application of a lesson that can be drawn from Wittgenstein to the Cartesian selfknowledge which is the other main component of the argument. When both of these elements are taken into account, it becomes clear that the McKinsey argument cannot justify a physical criterion for being outside the self. What notion of the self, then, can anti-individualist and Cartesian alike accept for the sake of argument until the issues between them are clarified? The Cartesian skeptical notion of the self might at first seem more neutral . By the Cartesian skeptical notion of the self, I mean the notion of a mind that can introspect all its own conscious, occurrent thought-contents and in particular can know what its own concepts are. However, this notion cannot be simply assumed in an attempt to defend Cartesian skepticism against an anti-individualist, since some would argue—for reasons we shall encounter shortly—that anti-individualism is both a conceptual truth and incompatible with the Cartesian degree of self-knowledge just described.3 In the end, the Cartesian skeptical notion of the self is not available in any case, even to skeptics. For we are ultimately fallible about our own concepts , for reasons which have gone largely unmentioned in this debate, despite having arguably paved the way for it.4 In brief, if it is to be an objective fact that my concepts mean something, then it must be possible that I have all the inward signs of meaning something by a given concept without actually doing so. This line of reasoning is more general than the anti-individualist views usually invoked—and it does not assume anything the skeptic questions. Section 2 will set out these reasons in detail. The result is that neither the Cartesian skeptical notion of the self nor the anti-individualist physical notion of the self can play the needed neutral role in the debate. This leaves still unanswered the question of what counts as external to the self—so that the issue between Cartesian skeptics and their anti-individualist opponents remains crucially undefined. What exactly are the implications for skepticism? Although the difficulties that will emerge with the McKinsey strategy for proving that there are physical objects are grist for skepticism in general, these difficulties do not vindicate external-world skepticism as such when the results of the first two sections are taken into account. Rather, as section 3 will explain, these difficulties point toward a broader skepticism—not the full-fledged Humean kind, yet one that still infiltrates the Cartesian realm. 1 Anti-Individualism 1.1 The McKinsey Argument As mentioned above, an argument originally due to McKinsey seems to offer a strategy for showing, without illegitimate empirical assumptions, that there are physical objects outside oneself. This strategy is doubly relevant to this paper. First, it articulates the anti-individualist argument against skepticism about external objects. But second, if it works it gives reason to concede the existence of...