Dissertations, Theses, and Capstone Projects

Date of Degree


Document Type


Degree Name





Graham Priest

Subject Categories



existence, indeterminacy, mathematics, mind-independence, ontological commitment, spatiotemporality


What is it for something to exist? This dissertation provides an answer to this question by giving a philosophical theory of existence in which the concept of existence in understood as a complex tri-partite notion. The account of existence defended here is arrived at by taking into consideration past philosophical theories of existence, the everyday and scientific uses of the notion, and also philosophical considerations about the nature of reality.

There are three conditions that are central to existence: spatiotemporality, mind-independence, and being a member of the quantificational domain of a true and complete scientific description about the world. To exist is to satisfy all three conditions. It is false that something exists if and only if it for each condition, it fails to satisfy it. And, therefore, we get a third case: if an entity satisfies some but not all of the conditions, then it is neither true nor false that it exists, so what follows is an account of indeterminate existence. For some entities, our best theoretical sharpening of our conception of existence still fails to determine whether they exist or not.

After arguing for each of the three conditions thoroughly, I strengthen the case for my theory of existence by explaining the consequences of its application. I provide several examples. Finally, I focus on the development of a philosophy of mathematics that takes into account that, given our theory of existence, it is neither true nor false that mathematical entities exist.

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