UNIVERSITY OF CALIFORNIA Santa Barbara On the Appeal to Naturalness in Metaphilosophy A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Philosophy by David Mokriski Committee in charge: Professor Dan Korman, Chair Professor Teresa Robertson Ishii Professor Nathan Salmon Professor Aaron Zimmerman March 2021 The dissertation of David Mokriski is approved. ____________________________________ Professor Dan Korman, Committee Chair ____________________________________ Professor Teresa Robertson Ishii ____________________________________ Professor Nathan Salmon ____________________________________ Professor Aaron Zimmerman March 2021 ii Acknowledgements I would like to thank everyone who contributed to my academic experience at UCSB in general and to the completion of this dissertation in particular. This includes the many professors and fellow graduate students who have indulged me in conversations about matters of (often highly speculative) metaphysics and philosophy more generally over the years. Thanks to Arnel Blake Batoon, Sherri Lynn Conklin, and Daniel Story for their feedback in our writing workshop, which helped motivate me to actually start putting words onto paper. Special thanks to my committee members Teresa Robertson Ishii, Nathan Salmon, and Aaron Zimmerman for providing helpful feedback on this and previous work and for encouragement and inspiration. And no one has contributed more to my academic achievements in graduate school than my advisor and committee chair Dan Korman. I am very grateful for all the hard work he put into advising me. Over the past several years, he has provided me hundreds of helpful comments, set clear goals to keep me productive, and pushed me to turn my ideas into publishable work. His criticism has always been constructive and fair, in spite of our philosophical differences—he is, after all, a staunch defender of “common sense”, while I typically seek to challenge it. I would also like to thank my friends and family for being extremely supportive during my time in graduate school, most notably my parents, who have always made it known how proud they are of me for whatever I do (despite having to frequently ask what it is that I do), and Thainá Coltro Demartini, who has been the best friend and partner I could ever ask for (even in the face of a deadly pandemic that has kept us on separate hemispheres). Finally, I would like to thank anyone who takes the time to read this dissertation. I hope you find something of value in it and forgive its flaws. iii Abstract This dissertation explores and defends the appeal to metaphysical naturalness in metaphilosophy. Naturalness is the gradable distinction between properties such as being green and being grue (i.e. green-and-discovered-before-3000-AD-or-blue-and-not-so- discovered), whereby one property seems like a “gerrymandered construction” relative to the other. This phenomenon is connected to other philosophically interesting phenomena such as fundamentality, similarity, simplicity, reference, and rationality, and these connections give naturalness a role to play in metaphilosophy, the philosophical subfield that investigates philosophy itself (methodological issues, the status of its disputes, etc.). In this dissertation, I defend first an account of naturalness, then some connections between naturalness and metaphilosophical issues, and finally some applications of these connections. I’ve organized the dissertation into three parts. Part I consists of two introductory chapters that introduce the reader to the two central topics of this dissertation, metaphilosophy and naturalness. In Chapter 1, I give a brief introduction to the field of metaphilosophy as I understand it, including some of its branches and the sorts of issues that arise in them. In Chapter 2, I give a thorough introduction to and defense of the notion of metaphysical naturalness, including its connection to fundamentality, similarity, simplicity, reference, and rationality. Part II consists of four chapters that lay out and defend the connections between naturalness and metaphilosophical issues. In Chapter 3, I connect naturalness to issues in the metaphysics of philosophy, including questions about the existence, reducibility, and objectivity of philosophical facts and properties. In Chapter 4, I connect naturalness to issues in the semantics of philosophy, including the questions of when philosophical iv terms are semantically indeterminate and when philosophical disputes are merely verbal. In Chapter 5, I connect naturalness to issues in the epistemology of philosophy, including the appropriate epistemic weight of certain theoretical virtues (simplicity, non- arbitrariness, and unification), the strength of analogical and arbitrariness arguments, and the threat of certain forms of skepticism about philosophy. In Chapter 6, I connect naturalness to issues in the conceptual ethics of philosophy (which consists of normative and evaluative questions about linguistic and conceptual choices), including the questions of when we should take a philosophical term as primitive, when philosophical disputes are substantive (in a distinctively normative sense), and when we should change the meaning of a philosophical term. Part III consists of three chapters that defend some applications of the above connections. In Chapter 7, I defend two theses about naturalness and semantic vagueness and discuss some implications for philosophical theories whose central theoretical terms are semantically vague. In Chapter 8, I defend two theses about naturalness and first- order pluralistic theories—that is, theories give an account of some phenomenon in terms of a complex, irreducible plurality of factors—and discuss some implications for such theories in philosophy. Finally, in Chapter 9, I defend myself against concerns of incoherence or self-defeat. The primary aim of this dissertation is to show how the appeal to naturalness can make a difference when addressing methodological and other foundational issues about philosophy. A secondary aim is to show how such an appeal tends to cause trouble for semantically vague and first-order pluralistic philosophical theories—ones that are often otherwise very plausible and worthy of the label ‘common sense’. v Table of Contents Acknowledgements............................................................................................................iii Abstract...............................................................................................................................iv Part I: Introduction...............................................................................................................1 Chapter 1: Metaphilosophy, or the Philosophy of Philosophy................................2 1.1 The Metaphysics of Philosophy.............................................................4 1.2 The Semantics of Philosophy.................................................................8 1.3 The Epistemology of Philosophy.........................................................14 1.4 The Conceptual Ethics of Philosophy..................................................17 1.5 Chapter Summary................................................................................21 Chapter 2: Metaphysical Naturalness, or “Nature’s Joints”..................................22 2.1 The Account.........................................................................................23 2.2 Fundamentality....................................................................................30 2.3 Similarity.............................................................................................35 2.4 Simplicity............................................................................................39 2.5 Reference.............................................................................................43 2.6 Non-Instrumental Theoretical Value...................................................57 2.7 Miscellaneous Roles............................................................................67 2.8 Naturalness Skepticism.......................................................................69 2.9 Chapter Summary................................................................................71 Part II: Connections...........................................................................................................72 Chapter 3: Naturalness in the Metaphysics of Philosophy....................................73 3.1 Nihilism...............................................................................................75 3.2 Reductionism.......................................................................................84 3.3 Objectivity...........................................................................................90 3.4 Chapter Summary..............................................................................102 Chapter 4: Naturalness in the Semantics of Philosophy......................................104 4.1 Semantic Indeterminacy....................................................................105 4.2 Verbal Disputes.................................................................................125 4.3 Chapter Summary..............................................................................134 Chapter 5: Naturalness in the Epistemology of Philosophy................................136 5.1 Theoretical Virtues............................................................................137