Research

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I argue that presentist theories share the vices of a manifestly unacceptable view, and so they should likewise be rejected. According to presentism, only present things exist, so that claims like '∃x(Dinosaur(x))’ and '∃x(Martian-Colony(x)' are false. Yet it is manifestly true that dinosaurs existed and (suppose) Martian colonies will exist. To capture these truths, presentism standardly appeals to primitive tense operators. Where ‘Pϕ’ is read as “It was the case that ϕ” and ‘Fϕ’ is read as “It will be the case that ϕ”, presentism endorses the truth of ‘P∃x(Dinosaur(x))’ and ‘F∃x(Martian-Colony(x))’, while denying that these tensed truths reduce to the existence of dinosaurs and Martian colonies in the past and future. 

According to tensed nihilism, there are no past, future, or even present things. Yet tensed nihilism captures manifest truths about the existence of humans in terms of primitive tense operators. Where ‘Cϕ’ is read as “It is presently the case that ϕ”, tensed nihilism endorses the truth of ‘C∃x(Human(x)’, while denying that this tensed truth is reducible to the existence of humans in the present. The vices that justify rejecting tensed nihilism also undermine presentism. For example, both views violate the principle that truth is grounded in being. Presentists offer a host of responses to this problem. But they are also available to tensed nihilism, or analogues thereof. Moreover, I argue that presentism is equally vulnerable to other objections to tensed nihillism. So because we should reject (analogues of) tensed nihilism, we should also reject presentism.

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I argue that growing block theory (GBT) seeds doubts about its motivations. According to GBT, always, new things come into being ex nihilo and then become past, remaining otherwise unchanged, making the present the "edge of being" of a four-dimensional (4D) growing block universe. Thus, GBT aims to capture the primary motivation for dynamic theories: that the present is privileged over the past and future. But the reasons to think this growing block is partly past are slim. They include that the block contains intuitively past things, like Socrates; that it contains intuitively past events, like Socrates’ death; and that the block is analogous to the non-presentist block universe of static theory. None of these reasons survive scrutiny, I argue. 

Moreover, three arguments suggest that GBT’s block is entirely present. First, recombining present things intuitively yields presentist possibilities. Yet recombination of presentist-friendly ontology yields a growing block just like GBT's. Second, a five-dimensional (5D) growing block could embed GBT’s block on its edge of being. The present in the 5D block is either its edge or its entirety. And either answer suggests that GBT's block is entirely present. Third, non-standard growing blocks—like one that grows from a point behind its edge of being—must be entirely present, on pain of absurdity. And the relevant similarity between such blocks and GBT’s suggests that the latter is also entirely present. Thus, we apparently lack good reason to believe that GBT's block is partly past, undermining GBT's primary motivation. Distinguishing GBT's block from a presentist growing block would ensure that the former is partially past. But I argue that distinguishing these blocks yields the same conclusion: supposing we inhabit GBT’s block, we should doubt that the edge of being is the present. I conclude by exploring how this argument generalizes to some other non-presentist dynamic theories, like moving spotlight theory.

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I defend multilocational endurantism, the view that some persisting objects are exactly located in each time at which they exist. Some argue that multilocational endurantism paradoxically makes things both three- and four-dimensional (3D and 4D); others argue that it violates the transitivity and irreflexivity of proper parthood; and still others argue that from a standard principle of recombination, multilocational endurantism yields absurd possible combinations of location and parthood. I show that multilocational endurantism can answer these problems by appealing to a framework of metaphysical grounding. 

Beyond standard assumptions about metaphysical grounding—for example, that it is asymmetric, transitive, and at least supports metaphysical explanation—this framework assumes that persisting things exist in virtue of facts about the objects that make them up. For example, a water molecule w’s existence is grounded in facts about the arrangement of its constituent hydrogen and oxygen molecules, h1, h2, and o. An account is offered of how these facts yield grounds of enduring objects' many locations—for example, w is located at the fusion of h1, h2, and o's locations at each time it exists—such that those things' locations are only ever 3D. And in terms of how enduring things' existence and locations are grounded, a reduction of their mereology is offered. This reduction explains how proper parthood is both transitive and irreflexive, even for enduring objects. And it blocks the third reductio's crucial premise that, if multilocational endurantism is true, then location and parthood are freely recombinable. In this way, theories of endurantism and metaphysical grounding form a mutually supportive package.

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I argue for multilocational endurantism—the view that some persisting things are exactly located in each time at which they exist—based on considerations of metaphysical grounding and quantum field theory (QFT). In addition to standard assumptions about grounding (that it is asymmetric, transitive, and at least supports metaphysical explanation) I also assume that persisting things exist in virtue of facts about the objects that make them up. For example, a water molecule w’s existence is grounded in facts about the arrangement of its constituent hydrogen and oxygen atoms. From this assumption, I argue for the conclusion that each non-fundamental existence fact has a unique ground. If so, then the grounds of w's existence plausibly include underlying facts about its constituent atoms across its history. The same goes for more basic objects, like quarks and leptons. According to QFT, these particles arise from undulations of corresponding fundamental fields. But no merely instantaneous flicker of a field gives rise to a particle; rather, some minimal duration of the field's wave-like behavior is required to ground a particle’s existence. Moreover, QFT predicts that these particles exist only very briefly, due to existence of a churn of virtual particles arising from random quantum fluctuations of the underlying fields. (More precisely, QFT predicts that particles are created and annihilated with each interaction.) 

Suppose for reductio that a short-lived quark q perdures, i.e. it is the fusion of distinct temporal parts, each exactly located at just one time. And consider any two of q’s temporal parts, tp1 and tp2. Given that q is sufficiently shortlived, the grounds of tp1 and tp2’s existence facts are minimal—any briefer, and the underlying field undulation would not ground the existence of any object. If so, then the grounds of tp1's existence are the same as the grounds of tp2's existence. Given that existence facts have unique grounds, it follows that these existence facts—and so the quarks they are about—are the very same. Rather than perduring, quark q multilocationally endures. Likewise for leptons. Finally, given that persisting objects inherit their manner of persistence from the objects that make them up, it follows that everything made up of quarks and leptons—including you and I—also multilocationally endure.