This edited volume of 13 new essays aims to turn past discussions of natural kinds on their head. Instead of presenting a metaphysical view of kinds based largely on an unempirical vantage point, it pursues questions of kindedness which take the use of kinds and activities of kinding in practice as significant in the articulation of them as kinds. The book brings philosophical study of current and historical episodes and case studies from various scientific disciplines (...) to bear on natural kinds as traditionally conceived of within metaphysics. Focusing on these practices reveals the different knowledge-producing activities of kinding and processes involved in natural kind use, generation, and discovery. -/- Specialists in their field, the esteemed group of contributors use diverse empirically responsive approaches to explore the nature of kindhood. This groundbreaking volume presents detailed case studies that exemplify kinding in use. Newly written for this volume, each chapter engages with the activities of kinding across a variety of disciplines. Chapter topics include the nature of kinds, kindhood, kinding, and kind-making in linguistics, chemical classification, neuroscience, gene and protein classification, colour theory in applied mathematics, homology in comparative biology, sex and gender identity theory, memory research, race, extended cognition, symbolic algebra, cartography, and geographic information science. -/- The volume seeks to open up an as-yet unexplored area within the emerging field of philosophy of science in practice, and constitutes a valuable addition to the disciplines of philosophy and history of science, technology, engineering, and mathematics. -/- Contributions from a diverse group of established and junior scholars in the fields of Philosophy and History and Philosophy of Science including Hasok Chang, Jordi Cat, Sally Haslanger, Joyce C. Havstad, Catherine Kendig, Bernhard Nickel, Josipa Petrunic, Samuli Pöyhönen, Thomas A. C. Reydon, Quayshawn Spencer, Jackie Sullivan, Michael Wheeler, and Rasmus Grønfeldt Winther. (shrink)

Recent work on Natural Kind Essentialism has taken a deflationary turn. The assumptions about the grounds of essentialist truths concerning natural kinds familiar from the Kripke-Putnam framework are now considered questionable. The source of the problem, however, has not been sufficiently explicated. The paper focuses on the Twin Earth scenario, and it will be demonstrated that the essentialist principle at its core (which I call IDENT)—that necessarily, a sample of a chemical substance, A, is of the same (...) kind as another sample, B, if and only if A and B have the same microstructure—must be re-evaluated. The Twin Earth scenario also assumes the falsity of another essentialist principle (which I call INST): necessarily, there is a 1:1 correlation between (all of ) the chemical properties of a chemical substance and the microstructure of that substance. This assumption will be questioned, and it will be argued that, in fact, the best strategy for defending IDENT is to establish INST. The prospects for Natural Kind Essentialism and microstructural essentialism regarding chemical substances will be assessed with reference to recent work in the philosophy of chemistry. Finally, a weakened form of INST will be presented. (shrink)

Both realist and anti-realist accounts of natural kinds possess prima facie virtues: realists can straightforwardly make sense of the apparent objectivity of the natural kinds, and anti-realists, their knowability. This paper formulates a properly anti-realist account designed to capture both merits. In particular, it recommends understanding natural kinds as ‘categorical bottlenecks,’ those categories that not only best serve us, with our idiosyncratic aims and cognitive capacities, but also those of a wide range of alternative (...) agents. By endorsing an ultimately subjective categorical principle, this view sidesteps epistemological difficulties facing realist views. Yet, it nevertheless identifies natural kinds that are fairly, though not completely, stance-independent or objective. (shrink)

In this paper I offer a unified causal account of natural kinds. Using as a starting point the widely held view that natural kind terms or predicates are projectible, I argue that the ontological bases of their projectibility are the causal properties and relations associated with the natural kinds themselves. Natural kinds are not just concatenations of properties but ordered hierarchies of properties, whose instances are related to one another as causes and effects (...) in recurrent causal processes. The resulting account of natural kinds as clusters of core causal properties that give rise to clusters of derivative properties enables us to distinguish genuine natural kinds from non-natural kinds. For instance, it enables us to say why some of the purely conventional categories derived from the social domain do not correspond to natural kinds, though other social categories may. (shrink)

Philosophers have long been interested in a series of interrelated questions about natural kinds. What are they? What role do they play in science and metaphysics? How do they contribute to our epistemic projects? What categories count as natural kinds? And so on. Owing, perhaps, to different starting points and emphases, we now have at hand a variety of conceptions of natural kinds—some apparently better suited than others to accommodate a particular sort of inquiry. (...) Even if coherent, this situation isn’t ideal. My goal in this article is to begin to articulate a more general account of ‘natural kind phenomena’. While I do not claim that this account should satisfy everyone—it is built around a certain conception of the epistemic role of kinds and has an obvious pragmatic flavour—I believe that it has the resources to go further than extant alternatives, in particular the homeostatic property cluster view of kinds. (shrink)

According to the received tradition, the language used to to refer to natural kinds in scientific discourse remains stable even as theories about these kinds are refined. In this illuminating book, Joseph LaPorte argues that scientists do not discover that sentences about natural kinds, like 'Whales are mammals, not fish', are true rather than false. Instead, scientists find that these sentences were vague in the language of earlier speakers and they refine the meanings of the (...) relevant natural-kind terms to make the sentences true. Hence, scientists change the meaning of these terms, This conclusions prompts LaPorte to examine the consequences of this change in meaning for the issue of incommensurability and for the progress of science. This book will appeal to students and professional in the philosophy of science, the philosophy of biology and the philosophy of language. (shrink)

This paper addresses philosophical issues concerning whether mental disorders are natural kinds and how the DSM should classify mental disorders. I argue that some mental disorders (e.g., schizophrenia, depression) are natural kinds in the sense that they are natural classes constituted by a set of stable biological mechanisms. I subsequently argue that a theoretical and causal approach to classification would provide a superior method for classifying natural kinds than the purely descriptive approach adopted (...) by the DSM since DSM-III. My argument suggests that the DSM should classify natural kinds in order to provide predictively useful (i.e., projectable) diagnostic categories and that a causal approach to classification would provide a more promising method for formulating valid diagnostic categories. (shrink)

The new externalist picture of natural kind terms due to Kripke, Putnam, and others has become quite popular in philosophy. Many philosophers of science have remained sceptical. Häggqvist and Wikforss have recently criticised this view severely. They contend it depends essentially on a micro-essentialist view of natural kinds that is widely rejected among philosophers of science, and that a scientifically reasonable metaphysics entails the resurrection of some version of descriptivism. It is argued in this paper that the (...) situation is not quite as dark for the new theory of reference as many critics suggest. There are several distinct questions here which should not be conflated and ought to be dealt with one by one. Descriptivism remains arguably problematic. (shrink)

This paper considers the problem of assigning meanings to empty natural kind terms. It does so in the context of the Twin-Earth externalist-internalist debate about whether the meanings of natural kind terms are individuated by the external physical environment of the speakers using these terms. The paper clarifies and outlines the different ways in which meanings could be assigned to empty natural kind terms. And it argues that externalists do not have the semantic resources to assign them (...) meanings. The paper ends on a sceptical note concerning the fruitfulness of using the Twin-Earth setting in debates about the semantics of empty natural kind terms. (shrink)

There are many ways of construing the claim that some categories are more “natural" than others. One can ask whether a system of categories is innate or acquired by learning, whether it pertains to a natural phenomenon or to a social institution, whether it is lexicalized in natural language or requires a compound linguistic expression. This renders suspect any univocal answer to this question in any particular case. Yet another question one can ask, which some authors take (...) to have a bearing on the issue of the naturalness of categories, is whether a system of categories constitutes a unique way of organizing a particular set of entities or phenomena, or whether there are other legitimate classification schemes that can coexist with it. Another way of putting this is by asking whether systems of categories can cut across one another, and if so, under what circumstances. Some philosophers have claimed that crosscutting systems of categories cannot exist as genuine natural kinds. This paper examines that claim and puts forward some counterexamples, concluding that this notion of natural kind is not in tune with scientific classification and ought to be rejected in favor of an alternative. (shrink)

The rosy dawn of my title refers to that optimistic time when the logical concept of a natural kind originated in Victorian England. The scholastic twilight refers to the present state of affairs. I devote more space to dawn than twilight, because one basic problem was there from the start, and by now those origins have been forgotten. Philosophers have learned many things about classification from the tradition of natural kinds. But now it is in disarray and (...) is unlikely to be put back together again. My argument is less founded on objections to the numerous theories now in circulation, than on the sheer proliferation of incompatible views. There no longer exists what Bertrand Russell called ‘the doctrine of natural kinds’—one doctrine. Instead we have a slew of distinct analyses directed at unrelated projects. (shrink)

Is there a plausible middle position in the debate between realists and constructivists about categories or kinds? Such a position may seem to be contained in the account of triangulation that Donald Davidson develops in recent writings. On this account, the kinds we pick out are determined by an interaction between our shared similarity responses and causal relations between us and things in our environment. So kinds and categories are neither imposed on us by the nature of (...) the world, nor imposed by us on an intrinsically unstructured reality. But the picture derivable from Davidson's account of triangulation can be interpreted in either of two ways. On one interpretation, it collapses into constructivism. On the other, it turns out to be very close to the most plausible versions of realism. It is argued that Davidson's attempts to distinguish his view from Putnam's realism about natural kinds are unsuccessful. So Davidson's account of triangulation does indeed suggest a plausible view of kinds. But that view is a version of traditional realist views, not an alternative to them. (shrink)

A large part of our exploration of the world consists in categorizing or classifying the objects and processes we encounter, both in scientific and everyday contexts. There are various, perhaps innumerable, ways to sort objects into different kinds or categories, but it is commonly assumed that, among the countless possible types of classifications, one group is privileged. Philosophy refers to such categories as natural kinds. Standard examples of such kinds include fundamental physical particles, chemical elements, and (...) biological species. The term natural does not imply that natural kinds ought to categorize only naturally occurring stuff or objects. Candidates for natural kinds can include man-made substances, such as synthetic elements, that can be created in a laboratory. The naturalness in question is not the naturalness of the entities being classified, but that of the groupings themselves. Groupings that are artificial or arbitrary are not natural; they are invented or imposed on nature. Natural kinds, on the other hand, are not invented, and many assume that scientific investigations should discover them. (shrink)

Despite the traditional focus on metaphysical issues in discussions of natural kinds in biology, epistemological considerations are at least as important. By revisiting the debate as to whether taxa are kinds or individuals, I argue that both accounts are metaphysically compatible, but that one or the other approach can be pragmatically preferable depending on the epistemic context. Recent objections against construing species as homeostatic property cluster kinds are also addressed. The second part of the paper broadens (...) the perspective by considering homologues as another example of natural kinds, comparing them with analogues as functionally defined kinds. Given that there are various types of natural kinds, I discuss the different theoretical purposes served by diverse kind concepts, suggesting that there is no clear-cut distinction between natural kinds and other kinds, such as functional kinds. Rather than attempting to offer a unique metaphysical account of ‘natural’ kind, a more fruitful approach consists in the epistemological study of how different natural kind concepts are employed in scientific reasoning. (shrink)

It has been argued recently that some basic emotions should be considered natural kinds. This is different from the question whether as a class emotions form a natural kind; that is, whether emotion is a natural kind. The consensus on that issue appears to be negative. I argue that this pessimism is unwarranted and that there are in fact good reasons for entertaining the hypothesis that emotion is a natural kind. I interpret this to mean (...) that there exists a distinct natural class of organisms whose behavior and development are governed by emotion. These are emoters. Two arguments for the natural kind status of emotion are considered. Both converge on the existence of emotion as a distinct natural domain governed by its own laws and regularities. There are then some reasons for being optimistic about the prospects for consilience in emotion theory. 1 The mantra 2 Griffiths on emotions as natural kinds 3 Panksepp on emotions as natural kinds 4 Emotion as a neurobiological kind 5 Emotion as a psychological kind 6 Response to the mantra 7 Unification or fragmentation? 8 Concluding remarks. (shrink)

This paper evaluates the Natural-Kinds Argument for cognitive extension, which purports to show that the kinds presupposed by our best cognitive science have instances external to human organism. Various interpretations of the argument are articulated and evaluated, using the overarching categories of memory and cognition as test cases. Particular emphasis is placed on criteria for the scientific legitimacy of generic kinds, that is, kinds characterized in very broad terms rather than in terms of their fine-grained (...) causal roles. Given the current state of cognitive science, I conclude that we have no reason to think memory or cognition are generic natural kinds that can ground an argument for cognitive extension. (shrink)

This paper maps the landscape for a range of views concerning the metaphysics of natural kinds. I consider a range of increasingly ontologically committed views concerning natural kinds and the possible arguments for them. I then ask how these relate to natural kind essentialism, arguing that essentialism requires commitment to kinds as entities. I conclude by examining the homeostatic property cluster view of kinds in the light of the general understanding of kinds (...) developed. (shrink)

The article examines the role of natural kinds in semantic theorizing, which has largely been conducted in isolation from relevant work in science, metaphysics, and philosophy of science. We argue that the Kripke–Putnam account of natural kind terms, despite recent claims to the contrary, depends on a certain metaphysics of natural kinds; that the metaphysics usually assumed—micro-essentialism—is untenable even in a ‘placeholder’ version; and that the currently popular homeostatic property cluster theory of natural (...) class='Hi'>kinds is correct only to an extent that fails to vindicate the Kripke–Putnam account. This undermines the metasemantics required for anti-descriptivist semantics. _1_ Introduction _2_ From Semantics to Metaphysics _3_ Metaphysics, Part I: The Demise of Micro-essentialism _3.1_ Original micro-essentialism _3.2_ Placeholder essentialism _4_ Metaphysics, Part II: Homeostatic Property Cluster Theory _5_ Prospects for Natural Kind Term Semantics. (shrink)

A standard requirement on natural kinds is that they be mind independent. However, many kinds in the human and social sciences, even the natural sciences, depend on human thought. This article suggests that the mind independence requirement on natural kinds be replaced with the requirement that natural kind classifications be defeasible. The defeasibility requirement does not require that natural kinds be mind independent, so it does not exclude mind dependent scientific (...) class='Hi'>kinds from being natural kinds. Furthermore, the defeasibility requirement captures the idea that natural kind classifications are tools for investigating the empirical world. (shrink)

It is commonly assumed that natural kind terms constitute a distinct semantic category. This idea emerged during the 1970's following Kripke's and Putnam's well-known remarks on natural kind terms. The idea has stayed with us, although it is now recognized that the issues are considerably more complex than initially thought. Thus, it has become clear that much of Kripke's and Putnam's discussions were based on rather simplified views of natural kinds. It also turns out that the (...) semantic issues are less straightforward than assumed - in particular, it is far from clear what it might mean to say that a kind term is rigid. Strikingly, however, these worries have not done much to undermine the confident assumption that natural kind terms form a special semantic category. In the paper I try to shake that confidence. I argue that although natural kind terms are no doubt important (for instance, from an explanatory point of view), we are certainly not warranted in concluding that they form a separate, semantic category among the kind terms. (shrink)

This article, which is intended both as a position paper in the philosophical debate on natural kinds and as the guest editorial to this thematic issue, takes up the challenge posed by Ian Hacking in his paper, “Natural Kinds: Rosy Dawn, Scholastic Twilight.” Whereas a straightforward interpretation of that paper suggests that according to Hacking the concept of natural kinds should be abandoned, both in the philosophy of science and in philosophy more generally, we (...) suggest that an alternative and less fatalistic reading is also possible. We argue that abandoning the concept of natural kinds would be premature, as it still can do important work. Our concern is with the situation in the (philosophy of the) life sciences. Against the background of this concern we attempt to set something of an agenda for future research on the topic of natural kinds in the (philosophy of the) life sciences. (shrink)

A paradigmatic case of rigidity for singular terms is that of proper names. And it would seem that a paradigmatic case of rigidity for general terms is that of natural kind terms. However, many philosophers think that rigidity cannot be extended from singular terms to general terms. The reason for this is that rigidity appears to become trivial when such terms are considered: natural kind terms come out as rigid, but so do all other general terms, and in (...) particular all descriptive general terms. This paper offers an account of rigidity for natural kind terms which does not trivialise in this way. On this account, natural kind terms are de jure obstinately rigid designators and other general terms, such as descriptive general terms, are not. (shrink)

Natural-kind essentialism faces an important but neglected difficulty: the problem of complex essences (PCE). This is the question of how to account for the unity of an instantiated kind-essence when that essence consists of multiple distinct properties, some of which lack an inherent necessary connection between them. My central goal here is to propose an essentialism-friendly solution to this problem. Along the way I also employ some points from that solution to argue for the necessary truth of essentialism (necessary, (...) that is, in all possible worlds in which there are material objects), and to support the essentialist ontology of laws over and against a major rival. (shrink)

This article uses the case study of ethnobiological classification to develop a positive and a negative thesis about the state of natural kind debates. On the one hand, I argue that current accounts of natural kinds can be integrated in a multidimensional framework that advances understanding of classificatory practices in ethnobiology. On the other hand, I argue that such a multidimensional framework does not leave any substantial work for the notion “natural kind” and that attempts to (...) formulate a general account of naturalness have become an obstacle to understanding classificatory practices. (shrink)

In this chapter I lay out a notion of philosophical naturalism that aligns with pragmatism. It is developed and illustrated by a presentation of my views on natural kinds and my theory of concepts. Both accounts reflect a methodological naturalism and are defended not by way of metaphysical considerations, but in terms of their philosophical fruitfulness. A core theme is that the epistemic interests of scientists have to be taken into account by any naturalistic philosophy of science in (...) general, and any account of natural kinds and scientific concepts in particular. I conclude with general methodological remarks on how to develop and defend philosophical notions without using intuitions. (shrink)

Recent challenges to non-traditional theories of natural kinds demand clarifications and revisions to those theories. Highlights: The semantics of natural kind terms is a special case of a general naturalistic conception of signaling in organisms that explains the epistemic reliability of signaling. Natural kinds and reference are two aspects of the same natural phenomenon. Natural kind definitions are phenomena in nature not linguistic or representational entities; their relation to conceptualized definitions is complex. Reference (...) and truth are special cases of a broader phenomenon of accommodation between aspects of signaling and epistemically relevant causal structures. (shrink)

Traditional debate on the metaphysics of gender has been a contrast of essentialist and social-constructionist positions. The standard reaction to this opposition is that neither position alone has the theoretical resources required to satisfy an equitable politics. This has caused a number of theorists to suggest ways in which gender is unified on the basis of social rather than biological characteristics but is “real” or “objective” nonetheless – a position I term social objectivism. This essay begins by making explicit the (...) motivations for, and central assumptions of, social objectivism. I then propose that gender is better understood as a real kind with a historical essence, analogous to the biologist’s claim that species are historical entities. I argue that this proposal achieves a better solution to the problems that motivate social objectivism. Moreover, the account is consistent with a post-positivist understanding of the classificatory practices employed within the natural and social sciences. (shrink)

It has recently been argued that the concept of natural kinds should be eliminated because it does not play a productive theoretical role and even harms philosophical research on scientific classification. We argue that this justification for eliminativism fails because the notion of ‘natural kinds’ plays another epistemic role in philosophical research, namely, it enables fruitful investigation into non-arbitrary classification. It does this in two ways: first, by providing a fruitful investigative entry into scientific classification; and (...) second—as is supported by bibliometric evidence—by tying together a research community devoted to non-arbitrary classification. The question of eliminativism then requires weighing off the benefits of retaining the concept against its harms. We argue that the progressive state of philosophical work on natural kinds tips this balance in favour of retaining the concept. (shrink)

The main contribution of this paper is a new account of how a community may introduce a term for a natural kind in advance of knowing the correct scientific account of that kind. The account is motivated by the inadequacy of the currently dominant accounts of how a community may do this, namely those proposed by Kripke and by Putman. Their accounts fail to deal satisfactorily with the facts that (1) typically, an item that instantiates one natural kind (...) instantiates several - 'the higher-level natural kinds problem', and (2) natural kinds often occur in nature in impure form - 'the composition problem' .On the account I propose, a term for a natural kind gains its reference by being associated with a recognitional capacity for that kind. I show how members of a scientifically ignorant community could have a recognitional capacity for a natural kind, say gold, as opposed to a certain kind of appearance, for instance the appearance that gold actually has. I argue that members of such a community can have recognitional capacities for particular natural kinds despite the actual or possible existence of duplicate kinds, e.g. water. After developing the account in detail, I show how it can deal with the two problems faced by Kripke's and Putnam's problem. The case of natural kind terms is crucial to the central debate in the philosophy of language and the philosophy of mind about whether we can refer non-descriptively to objects and kinds in the world. I take the account I propose to be a non-descriptive account of linguistic reference to natural kinds that can be used to support externalism in the philosophy of mind. (shrink)

This paper discusses whether it can be known a priori that a particular term, such as water, is a natural kind term, and how this problem relates to Putnams claim that natural kind terms require an externalist semantics. Two conceptions of natural kind terms are contrasted: The first holds that whether water is a natural kind term depends on its a priori knowable semantic features. The second.

This chapter discusses the distinction between natural kinds and natural properties. Some theorists deny the distinction, and claim that natural kinds can be identified with properties. For example, natural kinds might be understood as the perfectly natural properties, reducible to properties or the extensions of properties. Alternatively, one might argue that natural kinds and natural properties are distinct and that natural kinds could be considered as a sui (...) generis type of entity. For example, one might hold that natural kinds require a distinct kind of universal, substantival universal, or sortal. Alternatively, one might claim that properties themselves form natural kind groupings, in virtue of causal mechanisms. This chapter argues that classification into natural kinds can reflect real differences between natural groups, without the supplementary ontological distinction between properties and kinds. -/- . (shrink)

There have been many attempts to determine what makes a natural kind real, chief among them is the criterion according to which natural kinds must be mind-independent. But it is difficult to specify this criterion: many supposed natural kinds have an element of mind-dependence. I will argue that the mind-independence criterion is nevertheless a good one, if correctly understood: the mind-independence criterion concerns the unification principles for natural kinds. Unification principles determine how (...) class='Hi'>natural kinds unify their properties, and only those natural kinds that have a mind-independent unification principle should be considered real. (shrink)

The heterogeneity problem, which stems from the alleged difficulty of finding out what all pleasant experiences have in common, is largely considered as a substantial issue in the philosophy of pleasure, one that is usually taken as the starting point for theorizing about the essence of pleasure. The goal of this paper is to move the focus away from the heterogeneity problem and toward an alternative approach to pleasure. To do this, I first show that, although the approach stemming from (...) the heterogeneity problem has led to an interesting discussion about the essence of pleasure, it has usually endorsed an introspectionist methodology and other problematic assumptions that have led to doubtful results. I thus propose a natural-kind approach to pleasure, which seeks to determine what, if any, the natural kind of pleasure would consist in. This approach broadens the investigation of pleasure by enabling the use of a larger range of methodological tools, thus opening new promising directions for research. (shrink)

The traditional home for the concept of a natural kind in biology is of course taxonomy, the sorting of organisms into a nested hierarchy of kinds. Many taxonomists and most philosophers of biology now deny that it is possible to sort organisms into natural kinds. Many do not think that biological taxonomy sorts them into kinds at all, but rather identifies them as parts of historical individuals. But at any rate if the species, genera and (...) so on of biological taxonomy are kinds at all, there are various respects in which they fall short of the traditional requirements of naturalness. The members of biological taxa lack essential properties that make them members of a particular kind: any properties specific enough to belong only to members of the kind cannot be assumed to belong to all members of the kind. And if there are laws applying to members of biological taxa they are laws of very minor and local importance and, in view of the preceding point, at best probabilistic. (shrink)

Recently in the philosophy of psychology it has been suggested that several putative phenomena such as emotions, memory, or concepts are not genuine natural kinds and should therefore be eliminated from the vocabulary of scientific psychology. In this paper I examine the perhaps most well known case of scientific eliminativism, Edouard Machery’s concept eliminativism. I argue that the split-lump-eliminate scheme of con- ceptual change underlying Machery’s eliminativist proposal assumes a simplistic view of the functioning of scientific concepts. Conceiving (...) of scientific concepts as natural kind terms is an important reason for the impasse between Machery and anti-eliminativists, as both sides allude to properties of natural kinds in their contradicting arguments. As a solution I propose that, in order to develop a more satisfactory theory of conceptual change in science, one needs to distinguish between three different types of scientific concepts, hitherto conflated under the loaded notion of natural kind. (shrink)

What are biological species? Aristotelians and Lockeans agree that they are natural kinds; but, evolutionary theory shows that neither traditional philosophical approach is truly adequate. Recently, Michael Ghiselin and David Hull have argued that species are individuals. This claim is shown to be against the spirit of much modern biology. It is concluded that species are natural kinds of a sort, and that any 'objectivity' they possess comes from their being at the focus of a consilience (...) of inductions. (shrink)

When we ask what natural kinds are, there are two different things we might have in mind. The first, which I’ll call the taxonomy question, is what distinguishes a category which is a natural kind from an arbitrary class. The second, which I’ll call the ontology question, is what manner of stuff there is that realizes the category. Many philosophers have systematically conflated the two questions. The confusion is exhibited both by essentialists and by philosophers who pose (...) their accounts in terms of similarity. It also leads to misreading philosophers who do make the distinction. Distinguishing the questions allows for a more subtle understanding of both natural kinds and their underlying metaphysics. (shrink)

We articulate a view of natural kinds as complex universals. We do not attempt to argue for the existence of universals. Instead, we argue that, given the existence of universals, and of natural kinds, the latter can be understood in terms of the former, and that this provides a rich, flexible framework within which to discuss issues of indeterminacy, essentialism, induction, and reduction. Along the way, we develop a 'problem of the many' for universals.