Purpose-Relativity and Ontology

Serious ontology is the view that metaphysical debates about existence are deep, theoretical, quasi-scientific debates about the nature and constituents of reality. Serious ontology has been the dominant metaontology for the last few decades, but recently it has come under attack. Eli Hirsch’s Quantifier Variantism is one of the most compelling criticisms of serious ontology. According to Hirsch many ontological debates are merely verbal because the alleged rivals in these debates can each agree that the other side is saying something true given the meanings of the existential quantifier in their own language, and none of those quantifier meanings is objectively privileged. The most well developed response to skeptical metaontologies such as Quantifier Variantism is due to Theodore Sider’s (2011) Writing the Book of the World. Sider agrees that the meaning of the existential quantifier may vary in different languages. However, he argues that even though the quantifier variantist might be right that both parties to the debate make true existential claims, the debate might still be substantive. On Sider’s view it is substantive if one of the languages is objectively better than the other, where it is better if the quantifiers in the language map the structure of reality or carve perfectly at the world’s logical joints. I argue that Sider’s defense of serious ontology does not succeed, as he overlooks a very important assumption about the comparative evaluation of different languages. On my view, different languages could be comparatively evaluated only on the condition that they are introduced for the same purpose(s). Consider, for example, two countries, Leftia and Rightland, which share a border. The border is close to an inclined fault line according to which all Leftia and a very small part of Rightland in the region are on a lower wall and the almost all of Rightland is on a higher wall. Which language, geological or political, is objectively better at describing the region? It seems clear that the question ‘Which language is better?’ is incomplete without saying anything about the purpose of the description. But once we specify the purpose the answer seems to be fairly obvious. If the purpose of the description is to state geological facts (perhaps one of the two countries is planning to build a nuclear power plant in the region) then obviously the geological language is better, whereas if we aim to lay out the political facts (perhaps there is a significant archeological discovery on the border) then, of course, we should choose the political language. Hence, in order to claim that one language is better than the other they must serve the same purpose. If they do not have the same purpose we are not able to compare them at all. I argue that in most ontological debates, if not all, putatively rival languages are put forward for different purposes, and thus Sider’s way of reinstating serious ontology in the face of the threat of Quantifier Variantism fails. I consider the ontological debate over the existence of ordinary objects as a case study. I argue that in this debate between people like Lynne Baker and Trenton Merricks, putatively competing languages don’t have the same set of purposes; they are meant to do different things. Assuming that they are successful with respect to their purposes, we simply cannot deny either ontology on the grounds that one is objectively better than the other. I conclude, pace Sider, that there are many different books of the same world, and that, given that these different books are written for different purposes, they cannot be compared. For all we know it can be the case that different languages such as the language of economics, biology, physics, or sociology could mark the objective similarities and differences in the world equally well. So perhaps we need not a book of the world, but an ever-growing encyclopedia, to serve our ever-expanding purposes. The way ontologists can contribute to the writing of this encyclopedia, I argue, is not by engaging in debates about the complete inventory of what there is, but instead asking questions about the natures of the things that there are. By looking at both linguistic and non-linguistic practices concerning the objects in question, ontologists can answer questions such as under what conditions these kind of objects come into existence, how they persist, or how and on which entities their existence depends. Therefore, the conclusion is not that we should eliminate ontology altogether, but rather reorient its questions. In an appendix to my dissertation I give an example of how ontology may proceed along these lines, by taking up these questions for software where I argue that software is a kind of abstract artifact.