Abstract

Metaphysical naturalism centers on the claim that any answer to the question "what exists?" must be framed in agreement with our overall best scientific theory of the world. Naturalists hold that objects which play a central role in facilitating the overall simplicity and elegance of our scientific theory are accorded a special status—in short they have attained "indispensability." As advanced by Penelope Maddy, the Argument from Scientific Practice is designed to show that indispensability is fundamentally incompatible with another core naturalistic doctrine—ontological relativity. Under ontological relativity, what entities we take to exist is always determined relative to a background theory. Thus, under naturalism it seems that there is no way to determine in an absolute sense what exists. The challenge posed under the ASP is that the naturalist cannot justify commitment to certain indispensable entities given that either there is no empirical test is available or the entity in question is accepted only as a "useful" fiction which carries no ontological commitment. I argue that even if key features of the ASP are considered, the naturalist still can hold to both the indispensability thesis and ontological relativity