Explore the vast range of titles available.

Several philosophers have recently tried to define natural kinds in epistemic terms only. Given the persistent problems with finding a successful metaphysical theory, these philosophers argue that we would do better to describe natural kinds solely in terms of their epistemic usefulness, such as their role in supporting inductive inferences. In this paper, I argue against these epistemology-only theories of natural kinds and in favor of, at least partly, metaphysical theories. I do so in three steps. In the first section of the paper, I propose two desiderata for a theory of natural kinds. In the second section, I discuss one example of a ‘general’ epistemology-only theory, proposed by Marc Ereshefsky and Thomas Reydon, and argue that theories like theirs fail to provide adequate criteria of natural kinds. In the third section, I focus on one example of a ‘specific’ epistemology-only theory, proposed by P. D. Magnus, and use it to show why such theories cannot justify the claim that the proposed epistemic criteria account for the naturalness of kinds.

Natural kinds, real kinds, or, following J.S. Mill simply, Kinds , are thought to be an important asset for scientific realists in the non-fundamental (or “special”) sciences. Essential natures are less in vogue. I show that the realist would do well to couple her Kinds with essential natures in order to strengthen their epistemic and ontological credentials. I argue that these essential natures need not however be intrinsic to the Kind’s members; they may be historical. I concentrate on assessing the merits of historical essential natures in a paradigm case of Kinds in the non-fundamental sciences: species. I specify two basic jobs for essential natures: (1) offering individuation criteria, and (2) providing a causal explanation of the Kind’s multiple projectable properties. I argue that at least in the case of species historical essences are fit for both tasks. The principled resistance to Kinds with historical essences should also be cleared.

This article is an introduction to the Synthese Special Issue, Natural Kinds: Language, Science, and Metaphysics. The issue includes new contributions to some of the main questions involved in the present philosophical debates on natural kinds and on natural kind terms. Those debates are relevant to philosophy of language, philosophy of science, and metaphysics. In philosophy of language it is highly debated what the meaning of natural kind terms is, how their reference is determined, as well as whether there are differences and similarities between the semantics of natural kind terms and that of other sorts of kind terms. In philosophy of science, natural kinds are relevant because they are the basis for scientific classifications and play an explanatory role in scientific theories; thus one aim of science is to discover natural kinds and theorize about them. Natural kinds are also relevant in metaphysics, where many questions involving natural kinds are debated and especially those concerning the sort of entities we refer to when using natural kind terms, i.e., the ontological status of natural kinds; in this regard there are different views, such as conventionalism, realism and essentialism. Another metaphysical question is what it is that characterizes the naturalness of kind divisions. The introduction sketches the antecedents of some of the present views on natural kinds and natural kind terms, and indicates some of the topics dealt with in the articles that make up the issue, which can be classified in the following groups: (1) the metaphysics and epistemology of natural kinds (2) the semantics of natural kind terms and other kind terms (3) questions on species and (4) other related issues on natural kinds. However, many of the articles cover more than just one of these topics.

Philosophical treatments of natural kinds are embedded in two distinct projects. I call these the philosophy of science approach and the philosophy of language approach. Each is characterized by its own set of philosophical questions, concerns, and assumptions. The kinds studied in the philosophy of science approach are projectible categories that can ground inductive inferences and scientific explanation. The kinds studied in the philosophy of language approach are the referential objects of a special linguistic category—natural kind terms—thought to refer directly. Philosophers may hope for a unified account addresses both sets of concerns. This paper argues that this cannot be done successfully. No single account can satisfy both the semantic objectives of the philosophy of language approach and the explanatory projects of the philosophy of science approach. After analyzing where the tensions arise, I make recommendations about assumptions and projects that are best abandoned, those that should be retained, and those that should go their separate ways. I also recommend adopting the disambiguating terminology of “scientific kinds” and “natural kinds” for the different notions of kinds developed in these different approaches.

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.

This paper investigates interactive kinds, a class of kinds suggested by Ian Hacking for which classification generates a feedback loop between the classifiers and what is classified, and argues that human interactive kinds should be distinguished from non-human ones. First, I challenge the claim that there is nothing ontologically special about interactive kinds in virtue of their members being classified as such. To do so, I reject Cooper’s counterexample to Hacking’s thesis that kind descriptions are necessary for intentional action, arguing that classification (although not necessarily linguistic description) is required for intentional action. Having considered ways to characterise the metaphysics of interactive kinds and the semantics of kind terms, I argue that the fact that classification facilitates intentional action makes human interactive kinds ontologically distinctive because of the anomalous nature of the change which the kind-classification brings about. I then briefly examine further distinguishing features of human interactive kinds.

Objects have dispositions. Dispositions are normally analyzed by providing a meaning to disposition ascriptions like ‘This piece of salt is soluble’. Philosophers like Carnap, Goodman, Quine, Lewis and many others have proposed analyses of such disposition ascriptions. In this paper we will argue with Quine (‘Natural Kinds’, 1970 ) that the proper analysis of ascriptions of the form ‘ x is disposed to m (when C)’, where ‘ x ’ denotes an object, ‘ m ’ a manifestation, and ‘ C ’ a condition, goes like this: (i) ‘ x is of natural kind k ’, and (ii) the generic ‘ k s are m (when C)’ is true. For the analysis of the generic, we propose an analysis in terms of causal powers: ‘ k s (when C) have the causal power to m ’. The latter, in turn, is analyzed in a very precise way, making use of Pearl’s probabilistic graphical causal models. We will show how this natural kind-analysis improves on standard conditional analyses of dispositions by avoiding the standard counterexamples, and that it gives rise to precise observable criteria under which the disposition ascription is true.

Marc Ereshefsky’s project of eliminative pluralism holds that, as there is no unifying feature among all species concepts, we ought to doubt the existence of the species category. Here, I argue that one promising strategy for saving the species category is to reframe it as a natural kind after the practice turn. I suggest situating the species category within a recent account of natural kinds proposed by Marc Ereshefsky and Thomas Reydon called “scientific kinds”. Scientific kinds highlight ontological boundaries. More importantly, they recognize boundaries drawn from the lab and the field, not only from the armchair. The point of this exercise is to situate the species category within an account of natural kinds that is sensitive to scientific practice. In order to argue for a realist interpretation of the species category, and not merely a pragmatic one, I rely on an approach to scientific metaphysics from Ken Waters that shifts the attention from “theory focused” to “practice-centered” analysis.

Rigid expressionism is the view that all natural kind terms and many other kind terms are rigid designators. Rigid expressionists embrace the ‘overgeneralization’ of rigidity, since they hold that not just natural kind terms but all unstructured kind terms are rigid designators. Unfortunately overgeneralization remains a defeating problem for rigid expressionism. It runs together natural kind terms and nominal kind terms in a way that enforces a false semantic uniformity. The Kripke/Putnam view of natural kind terms minus the claim of rigidity is correct, but a traditional descriptivist theory is appropriate for nominal kind terms. None of them should be thought of as either rigid or non-rigid, however.

We need to distinguish two sorts of natural kinds (NKs), scientific and common NKs, because the notion of NK, which has to satisfy demands at three different levels—ontological, semantic and epistemological—, is subject to two incompatible sets of constraints. In order to prove this, I focus on the much-discussed case of jade (how can we account for the fact that \"jade\", which demonstrated all the features of an NK-term until the 1860s, nowadays applies indistinctly to two different chemical NKs, jadeite and nephrite?). In the first part of the paper, I show that the current accounts are unsatisfactory because they are inconsistent. In the process, I explain why LaPorte's (Natural kinds and conceptual change, Cambridge University Press, Cambridge, 2004) analysis of \"jade\" as a vernacular NK-term with an open-texture meaning does not offer a way out. Using a reductio ad absurdum argument, I conclude that according to the main tenets of NK-term theories, today's \"jade\" has to be an NK-term, and jade thereby an NK. In the second part of the paper, I argue for this conclusion in a positive manner. First, I present a series of thought experiments demonstrating that today's \"jade\" has the specific features of an NK-term. Then, I show that the kind that we presently call \"jade\" exhibits the typical ontological and epistemological features of an NK. More generally, I expound on why common NKs are more than mere classes, and why categories such as \"jade\" are useful in many inferences and explanations.