Humboldt-Universität zu Berlin - Classical German Philosophy

Metaphysical Explanation


Catharine Diehl

PhD Project


This project investigates whether the concept of metaphysical explanation or grounding can elucidate metaphysical debates and address deflationary challenges. According to several prominent recent accounts, the task of metaphysics is to determine “the structure of the world” (Schaffer 2009: 379)—a conception born of dissatisfaction with Quine’s characterization of ontology as exclusively concerned with questions of existence. Metaphysical structure concerns relations of fundamentality: metaphysics deals with the questions of what is fundamental, what is derivative, and what the relations among these items are. Schaffer describes this conception of metaphysical structure as “ordered” and contrasts it to a “flat” structure where “the target of metaphysical inquiry is an unstructured list of existents” (2009: 355).

Schaffer offers his Neo-Aristotelian metaphysical program as a competitor to what he considers the mainstream Quinean consensus. He appears to assume that Quine has effectively answered Carnapian worries. In contrast, I propose to use the idea of metaphysical explanation to address Neo-Carnapian and other deflationary concerns with mainstream metaphysical realism. I shall suggest that the concept of metaphysical explanation can provide the “cognitive content” Carnap and those inspired by his work find lacking in metaphysical disputes. In “Empiricism, Semantics, and Ontology,” Carnap (1950) argues that ontological questions such as “Do numbers exist?” are either internal to a particular framework, in which case they receive trivial answers, or external to a framework and thus meaningless because they lack a context for evaluating their truth or falsity. In contrast to this vision of meaning, the realist defender of ontological claims will argue that they acquire meaning compositionally: in virtue of understanding the quantifier and the term “number,” we can know that “Numbers do not exist” picks out a proposition that is either true or false. Carnap’s own criterion for a statement to be meaningful is tied to his now-unpopular verificationism, but recent deflationists such as Eli Hirsch (2002, 2009) have questioned other elements of the realist’s story. The starting point for deflationism, however, is that ontological questions are in some sense “empty” or lacking cognitive content. We do not even know, in non-question-begging terms, in what the truth of an ontological question would consist.

I hope to show that the notion of metaphysical dependence can help resolve this impasse by providing an account of metaphysical inquiry that would yield this cognitive content. Such an account would start from the ubiquity of uncontroversially intelligible grounding claims, such as Fine’s examples, “The fact that the ball is red and round obtains in virtue of the fact that it is red and the fact that it is round” and “The fact that the particle is accelerating obtains in virtue of the fact that it is being acted upon by some net positive force” (forthcoming: 1). While many of these claims, such as the second example, might be taken as instances of physical grounding relations, the hypothesis of the dissertation is that some of them are properly metaphysical. The dissertation project thus begins with an attempt to give a satisfying account of the meaningfulness of metaphysical debates through grounding, but it is not committed to all ontological questions turning out to be meaningful. Instead, the primary goal is to develop a concept of metaphysical explanation that will provide a framework through which to evaluate first-order metaphysical disputes.


E-mail: catharine.diehl(at)