Natural Kind Realism, Taxonomic Pluralism, and Relative Fundamentality by Ka Ho Lam A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Philosophy University of Alberta © Ka Ho Lam, 2019 Abstract I argue that in order to resolve the debate between taxonomic monism and taxonomic pluralism, we should construe the reality of natural kinds in terms of relative fundamentality: a natural kind is real if and only if it is more fundamental than its members, whose reality is taken for granted in the context of this debate. Taxonomic monism upholds that there is only one correct way of classifying entities into natural kinds within a given scientific domain; taxonomic pluralism maintains that there are different but equally correct ways of classifying entities into natural kinds within a given scientific domain, and these different ways disagree with each other. The monism/pluralism debate has reached a stalemate, as the two positions conceive the reality of natural kinds in different ways. While taxonomic monists characterize the distinction between natural and non-natural kinds in metaphysical terms, taxonomic pluralists approach this distinction in epistemic, viz., naturalist, terms. According to this approach, natural kinds are groupings that underwrite successful epistemic practices in the sciences, such as explanation and induction. As I argue in this dissertation, however, this naturalist approach alone does not secure taxonomic pluralism. First, it fails to provide the requisite realist commitment desired by taxonomic pluralists; second, it fails to ensure that the different ways of classifying entities in a given domain into natural kinds genuinely disagree with each other, as proclaimed by pluralists. In the face of these two problems, I argue that taxonomic pluralists should give up their anti-metaphysical stance and formulate the reality of natural kinds in terms of relative fundamentality. This formulation reorients the monism/pluralism debate so that different classifications of entities into natural kinds can be ranked by their degree of relative fundamentality, according to which ii membership in a kind posited by a more fundamental classification would account for membership in a kind posited by a less fundamental classification. iii Acknowledgements First, I want to express my deepest thanks to my dissertation supervisor, Prof. Kathrin Koslicki. Her patience and support made the whole dissertation writing process a wonderful, rewarding intellectual journey. And her enthusiasm for learning has reignited my love for philosophy. I am indebted to Prof. Ingo Brigandt for his valuable advices. As a member of my dissertation committee, Ingo has opened up to me new perspectives in thinking about science and philosophy of science, which are integral to my thesis. I am very fortunate to have Prof. Bernard Linsky as part of my dissertation committee. His tireless curiosity and childlike wisdom made me never feel alone in my quest for knowledge. Also, I am grateful to Prof. Jeff Pelletier for his comments and suggestions on my dissertation. Indeed, it was a pleasure to have Jeff and Bernie as my teachers in the philosophy of language and the history of analytic philosophy. Thanks everyone in the Department of Philosophy at the University of Alberta. It is a lovely department. My heartiest thanks go to Arlene Oak, for giving me a home in Edmonton. And I am honored to have Richard and Vivien Bosley as my friends. I should also mention that David Low has shared with me a lot of insights about films and philosophy. I would like to thank Josephine Lau for reading the manuscript. Also, a iv special thank you to Arthur Chin, Max Deutsch, and Kelly Trogdon, for encouraging me to pick up philosophy again (and buying me drinks all the time). The last few months were a tumultuous time for my city. Our lives and liberty are at stake. Yet, the spirit, courage, and caring of the people have carried me through. Finally, I want to thank my brothers and my parents, for giving me the freedom to pursue what I want. v Table of Contents Page Abstract……………………………………………………………………………….ii Acknowledgements…………………………………………………………………..iv Introduction………………………………………….…………………………….…1 Chapter 1 The Realism of Taxonomic Pluralism I. Introduction……………………………………………………………7 II. What are natural kinds?........................................................................10 III. The naturalist reading and taxonomic pluralism……………………..16 IV. Natural kind realism and mind-independence………………………..20 V. Khalidi: projectibility and nodes in causal networks………………...28 VI. Problems of Khalidi’s natural kind realism…………………………..31 VII. Boyd: “accommodationism” and disciplinary matrix……………......36 VIII. Problems of Boyd’s natural kind realism………………………...…..42 IX. What should a natural kind realist be realist about?.............................47 X. Conclusion…………………………………………………………....51 Chapter 2 Natural Kind Realism, Irreducibility, and Relative Fundamentality I. Introduction…………………………………………………………..53 II. Irreducibility: the prima facie reasons……………………………….55 III. Irreducibility: natural kind realism vs. taxonomic pluralism………...56 IV. Ontological reduction: eliminative vs. conservative…………………59 V. The paradox of eliminative (ontological) reduction………………….64 VI. Quine: ontological reduction and ontological commitment………….70 VII. Problems of the neo-Quinean notion of ontological commitment.......79 VIII. Relative fundamentality and natural kind realism……………………81 IX. Metaphysical dependence and metaphysical explanation……………87 X. Kind-members reduction……………………………………………..89 XI. A potential problem of the explanatory construal……………………95 XII. Conclusion……………………………………………………………99 vi Chapter 3 Taxonomic Disagreement I. Introduction…………………………………………………………101 II. Monism, pluralism, and taxonomic disagreement………………….104 III. Taxonomic disagreement and crosscutting…………………………107 IV. The epistemological argument and taxonomic pluralism…………..110 V. The epistemological argument and individuality pluralism………...114 VI. The classification of “organisms”…………………………………..123 VII. The individuation of “organisms”…………………………………..129 VIII. Conclusion………………………………………………………......135 Chapter 4 Relative Fundamentality between Classifications I. Introduction……………………………………………………..…..142 II. Taxonomic Pluralism in chemistry…………………………………144 III. Khalidi’s taxonomic pluralism……………………………………...150 IV. Boyd’s taxonomic pluralism………………………………………..154 V. Relative fundamentality revisited…………………………………...157 VI. The classification of nuclides……………………………………….164 VII. Explanatory asymmetry……………………………………………..170 VIII. Conclusion…………………………………………………………..175 Conclusion………………………………………………………………………….179 Bibliography…………………………………………………………………….…184 vii Introduction Taxonomic pluralism is the view that there are multiple correct ways to classify individual entities within a given scientific domain. For instance, a taxonomic pluralist may maintain that, although evolution is central to biological study, a phenetic taxonomy, which classifies living organisms according to their morphological similarities, is as correct as a phylogenetic taxonomy, which groups organisms into species according to their common ancestry. Likewise, a taxonomic pluralist may insist that classifying chemical nuclides according to their mass number is no less correct than classifying them according to their atomic number, despite the fact that the latter classification forms the periodic table. I challenge this view in this dissertation. Yet, I do not follow in the footsteps of the traditional taxonomic monists. Traditionally, taxonomic monists argue that the world comes with a natural-kind structure to which the correct classification must correspond. And they formulate this natural-kind structure by appealing to various metaphysical principles. An example of these metaphysical principles is essentialism, which upholds that every entity at issue possesses a set of intrinsic properties that are both necessary and sufficient for its identity. If essentialism is correct, a monist conclusion is imminent: the correct classification should be the one that captures the real essences of things that constitute the natural-kind structure of the world, instead of the nominal essences we conventionally attribute to things. On the contrary, in challenging taxonomic pluralism, I espouse the naturalist stance endorsed by its proponents. The naturalist stance prioritizes empirical findings 1 over metaphysical considerations in thinking about natural kinds. Accordingly, natural kinds are understood as groupings that underwrite successful scientific practices such as explanation, induction, and prediction. Taxonomic pluralists argue that scientists’ diverse epistemic concerns in different investigative contexts are likely to call for different ways of classifying the individual entities in a given domain. Emphasizing the epistemic roles of natural kinds in scientific investigations, taxonomic pluralists further indicate that, since those metaphysical principles employed by their monist opponents fail to concur with empirical evidence and scientific theories, we should reject taxonomic monism. For example, the aforementioned doctrine of essentialism, when being applied to the classification of living organisms, is at odds with evolutionary theory. If we postulate that each individual organism possesses a set of intrinsic properties essential to its identity and that this set of properties also determines what species