Abstract

Many contemporary philosophers accept a strong generalization of Hume's denial of necessary causal connections, in the form of Hume's dictum (HD), according to which there are no metaphysically necessary connections between distinct, intrinsically typed entities. Hume's version of his dictum occurs during his investigation into the source of the idea of causal connection. The most powerful role that HD plays in Lewis's system concerns its providing a basis for, as Lewis puts it, a "principle of plentitude" that will guarantee "that the worlds are abundant, and logical space is somehow complete". Lewis's combinatorialism promises to provide a principled, extensionally adequate, and reductive generator of metaphysical modal space. Beyond combinatorialism, there are many other accounts of metaphysical modality that need to be considered, not just with an eye to extensional adequacy but also to the clear desideratum to provide an account of the space of metaphysical modality that is principled.