Issues in the Metaphysics of Material Objects

Date of Award

May 2020

Degree Type


Degree Name

Doctor of Philosophy (PhD)




Mark Heller


Composition, Fission, Fundamentality, Material objects, Vagueness

Subject Categories

Arts and Humanities


This dissertation discusses various issues in the metaphysics of material objects. The main thread running through most chapters is that there is a moral version of the too-many-thinkers problem that afflicts a wide range of views.

According to diachronic universalism, every series of objects composes something over time. Some philosophers have argued that if diachronic universalism is true, then presently indiscernible objects can come to differ in intuitively unacceptable ways. In chapter 1, “Supervenience Arguments against Diachronic Universalism”, I argue that these arguments are in tension with an independently plausible mereological principle. In light of this tension, I suggest we reject the arguments in question, and embrace diachronic universalism.

In chapter 2, “Should the Number of Overlapping Thinkers Count?”, I discuss a problem for the cohabitation account of fission—that is, the view that all the persons that result from a fission event cohabit the same body prior to fission. Suppose that Manuel and Jimena are in the same amount of pain. Unlike Jimena, however, Manuel will undergo fission next week. Fortunately, you have a spare painkiller, but who should you give it to? Intuitively, you have no more reason to give it to one or the other. According to the cohabitation account, however, there are actually two persons cohabiting Manuel’s body. But then you should arguably give them the pill, since doing so alleviates the pain of more beings. One response argues that giving him the pill alleviates the same amount of pain as giving it to Jimena because the two persons in Manuel’s body share one pain. Since what matters is the quantity of pain, you have no more reason to give it to one or the other. I argue that this response has implausible consequences with respect to certain conjoined twinning cases, and that it presupposes an objectionably fetishistic view of pain.

In the next two chapters, I turn to the issue of vagueness. Intuitively, it may be vague whether an object is a part of another object. For instance, it may be vague whether a certain hangnail is a part of David. According to the metaphysical account, this is an instance of metaphysical vagueness. Mark Heller argues that the metaphysical account lacks an adequate explanation of the context dependency of our judgments about indeterminacy. In chapter 3, “A Counterpart-Theoretic Response to Heller’s Argument against Metaphysical Indeterminacy”, I defend the metaphysical account from this objection. I argue that Elizabeth Barnes’ counterpart-theoretic account provides an adequate explanation of the phenomenon in question.

In chapter 4, “Vagueness, Parthood, and Fundamentality”, I discuss a non-standard linguistic account of vagueness. On this account, it is vague whether the hangnail is a part of David not because “David” is vague, but because “part of” is vague. On one version of the account, “part of” is also fundamental—hence some fundamental expressions are vague. But I give some reasons to think that no fundamental expression is vague. Thus, I focus on a version of the account that tries to accommodate that thought, and argue that the resulting view carries some undesirable commitments.

In chapter 5, I argue against a common view in the metaphysics of fundamentality, according to which what makes a language ideal is that all its primitives are fundamental. I argue that this view struggles to distinguish quantifier variance from ontological pluralism, and that we should therefore reverse the direction of analysis: what makes an expression fundamental is that it is a primitive of some ideal language.


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