Why Lewis Would Have Rejected Grounding

Notions of ‘grounding’, ‘metaphysical dependence’, and ‘ontological priority’ have become central to the twenty-first century revival of pre-critical metaphysics. Would David Lewis have approved of such developments? This chapter answers this question in the negative. Lewis would have rejected appeals to ‘grounding’, ‘metaphysical dependence’, and ‘ontological priority’. Rounding out and developing neglected and under-appreciated aspects of his views, we argue that Lewis would have held (1) that such notions aren’t needed and (2) that they’re not intelligible. It is frequently claimed that such notions as ‘grounding’ etc. are needed because the notion of ’supervenience’, which is central to Lewis’s philosophy, is too crude an explanatory tool to help us understand, for example, the relationship between the mental and the physical. We argue such claims are mistaken because Lewis never intended ‘supervenience’ to be employed in isolation from his other views about physicalism, folk psychology, and conceptual analysis. We also argue that Lewis was committed to denying that singletons metaphysically depend upon their members because of his structuralist approach to the philosophy of mathematics. It is a further claim often made that grounding is a relation between facts or that grounding is a relation that holds of metaphysical necessity. We argue that Lewis would have dismissed such claims as unintelligible because of his opposition to metaphysical necessity and Kripkean essentialism. We cover not only Lewis’s published writings but also his correspondence and other manuscripts which remained unpublished during his lifetime.