Scientific enquiry and natural kinds: From planets to mallards a philosophical monograph by P.D. Magnus pmagnus<at>fecundity.com This is the authors' final draft. Any citations should refer to the final typeset book, published by Palgrave Macmillan. In addition to canonical pagination and nice binding, the book has a cool picture of mallards on the cover. DOI: 10.1057/9781137271259 c 2012 P.D. Magnus, except where indicated; some figures are used by per- mission or under open licenses Acknowledgements5 Introduction7 1 How to think about natural kinds 10 A Why history is no help...................... 11 B Some criteria considered..................... 13 B.1 The induction assumption................ 14 B.2 The essence assumption................. 24 B.3 The science assumption................. 25 B.4 The law assumption................... 26 B.5 Artifacts and artificial kinds............... 28 B.6 The sharpness assumption................ 31 B.7 Starting with language.................. 34 B.8 The intrinsic feature assumption............. 37 B.9 The hierarchy assumption................ 41 1 B.10 The scarcity assumption................. 43 B.11 The implicit simpliciter assumption........... 44 C Keeping score........................... 50 2 A modest definition 52 A First formulation......................... 52 B More or less natural kinds.................... 54 B.1 Lessons from underdetermination............ 55 B.2 The lessons applied.................... 57 C Induction redux.......................... 59 D Natural kinds for settled science................. 61 D.1 Example: the domain of chemistry........... 62 D.2 Fungible kinds....................... 66 3 Natural kinds put to work 72 A Eight planets, great planets................... 72 A.1 Numerology and asteroids................ 74 A.2 Enter Pluto........................ 75 A.3 The constraints of astronomy.............. 78 A.4 Natural kinds and the fate of Pluto........... 82 B The abundance of living things................. 87 B.1 Particular species (buzz, buzz).............. 89 B.2 The species category................... 91 B.3 How species are and are not natural kinds....... 97 C Thinking outside the box..................... 99 C.1 Tasks and processes.................... 100 C.2 Distributed cognition................... 101 C.3 What the natural kind is not.............. 104 D Further examples......................... 105 4 Practical and impractical ontology 106 A An unreasonable dichotomy................... 106 A.1 Natural kinds and bicameral legislation......... 108 A.2 Amphibolic pragmatism................. 112 A.3 The pragmatists' hope of convergence.......... 116 A.4 Engaging the world.................... 117 A.5 The practical as leverage on the real.......... 120 B Deep metaphysics......................... 121 P.D. Magnus · Scientific Enquiry and Natural Kinds · 2 B.1 Bad arguments for realism................ 123 B.2 Realism and metaphysical depth............. 125 5 The menace of triviality 129 A Cheap similarity.......................... 130 B Project-relative kinds....................... 132 B.1 Promiscuous realism................... 132 B.2 Cooking up natural kinds................ 135 C Agent-relative kinds........................ 139 C.1 Meerkat threats and alarms............... 139 C.2 Unicorns and fictobiology................ 142 C.3 Constellations....................... 144 D Coda on promiscuity....................... 147 6 Causal processes and property clusters 148 A Species as the specimen of an HPC............... 150 A.1 Worries about polymorphism.............. 152 A.2 Getting over similarity fetishism............. 157 A.3 Natural kinds and systematic explanation....... 160 B Species and token histories.................... 165 B.1 The tigers of Mars.................... 166 B.2 Hybrids and separate origin............... 168 C RE: ducks, the species problem redux.............. 171 D Historical individuals....................... 175 D.1 Sets and sums, a metaphysical non sequitur...... 176 D.2 Metaphysical puzzles about change........... 181 D.3 Individualism and HPCs................. 182 E HPC thinking beyond token causes............... 183 E.1 The waters of Mars.................... 184 E.2 The Unity Problem.................... 187 F Coda on HPCs.......................... 189 7 Conclusion 191 P.D. Magnus · Scientific Enquiry and Natural Kinds · 3 List of Figures 1.1 Projectible predicates for clearly ordered kinds......... 19 1.2 Projectible predicates for unordered kinds........... 20 2.1 Projectible predicates in a restricted domain.......... 61 3.1 Estimates of Pluto's mass.................... 77 3.2 Our solar system......................... 78 3.3 Lagrange points.......................... 80 3.4 Anglerfish cladogram....................... 94 4.1 Boyd's idiom........................... 110 4.2 Three views about natural kinds................. 120 6.1 Female Linophryne lucifer .................... 160 6.2 Female and male Linophryne arborifera ............. 161 6.3 Sets versus fusions........................ 179 4 Acknowledgements This book took shape over the course of a semester, while I was a visiting fellow at the Center for Philosophy of Science in Pittsburgh. Yet the ideas are ones that I have been thinking about for a long time, and so I have a long list of intellectual debts. I began thinking about natural kinds in the last century, when I was a graduate student in San Diego. I studied with Philip Kitcher, when he was reconsidering the view he had defended in The Advancement of Science (1993) and working toward Science, Truth, and Democracy (2001). I urged him to be more of a pragmatist, and he urged me to be more of a realist. It is possible that we have switched places. When Philip left UCSD, I was advised first by Sandra Mitchell and later by Paul Churchland. My disserta- tion was on the underdetermination of theory by data, and worrying about underdetermination kept me busy for several years. I still thought about realism and natural kinds off and on. At the Philos- ophy of Science Association meeting in 2004, I had a late night conversation about natural kinds in the hotel bar with Richard Boyd, John Dupr´e,Jay Odenbaugh, Michael Weisberg, and Robin Hendry. Not too long after that, I started a blog. I made a series posts in 2006 about the relation between realism and ontological pluralism. I had a rewarding conversation in the com- ments section with Jay Odenbaugh, Matt Brown, and Greg Frost-Arnold. In Spring 2010, I was invited to give a talk at Cornell University. They encouraged me to present work-in-progress, so I gave a paper trying to de- velop my still half-baked thoughts on natural kinds. I thank the helpful and indulgent audience, especially Adam Bendorf, Karen Bennett, Matti Eklund, and Nico Silins. In Fall 2010, I had just gotten tenure at the University at Albany, and I spent the semester at the Center for Philosophy of Science. There I began to make a thorough, systematic slog through the literature. I met lots of 5 people in Pittsburgh, and they would ask politely what I was working on. I ruthlessly exploited this opportunity to try out a succession of possible positions. Showing up to my Center office every morning, I began writing on natural kinds in earnest. Notes grew to the size of papers, papers grew to the size of chapters, and without planning to be I was on the way to writing a book. I benefitted from interacting with all of the philosophers who were visiting the Center that semester. I extend special thanks to Heather Douglas, Ka- reem Khalifa, Bert Leuridan, Richard Samuels, and Peter Vickers. Thanks are also due to many members of the Pittsburgh philosophical community who gave me feedback on parts of the project, especially Jim Bogen, Julia Bursten, David Danks, Eduoard Machery, Sandy Mitchell, and Jim Wood- ward. A special shout out is due John Norton, then director of the Center, who was a key organizer for lots of interactions and was himself a smart in- terlocutor. I gave a talk as part of the Center's lunchtime colloquium series which covered what became the first chapters of the book. The discussion of planets (Chapter 3 xA) was presented to the visiting fellows reading group in Pittsburgh and delivered as a talk at City College of New York in November 2010. The discussion of ducks and seadevils (Chapter 6 xA) was presented to the reading group in Pittsburgh, presented at Metaphysics & Philosophy of Science in Toronto, May 2011, and published in Philosophy and Biol- ogy (Magnus 2011a). Thanks to Jonathan Birch and Joseph McCaffrey for pointing me toward interesting biological examples. Thanks to Cristyn Magnus, who discussed many of the ideas as I mulled them over, read fragments of drafts, and encouraged me to actually pull it together. Thanks to my colleagues who I harangued about natural kinds over the years, especially Ron McClamrock and Brad Armour-Garb. Ingo Brigandt read a draft of the book and provided many helpful comments. I used the manuscript as part of a graduate seminar at the University at Albany in Fall 2011. Thanks to the participants for their contributions, especially to Brian Deinhart, Chris DeLeo, Daniel Feuer, John Milanese, Tiffany Redies, and Damian Thibeault. This attempt to trace out influences on my thinking no doubt leaves out profound ones, and I will inevitably fail to acknowledge people whom I surely ought to thank. Thanks to all of them, too. P.D. Magnus · Scientific Enquiry and Natural Kinds · 6 Introduction In Plato's Phaedrus, Socrates is concerned with how things are grouped to- gether and how they