ARE NATURAL KINDS REDUCIBLE?

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 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.

Essentialism is widely regarded as a mistaken view of biological kinds, such as species. After recounting why (sections 2-3), we provide a brief survey of the chief responses to the “death of essentialism” in the philosophy of biology (section 4). We then develop one of these responses, the claim that biological kinds are homeostatic property clusters (sections 5-6) illustrating this view with several novel examples (section 7). Although this view was first expressed 20 years ago, and has received recent discussion and critique, it remains underdeveloped and is often misrepresented by its critics (section 8).

Dialectica, 1992

In this paper I try to make sense of and give provisional answers to question like: Are there interesting theories about natural kinds (distinguishing them form other kinds)? Are some classifications or categorisations more natural than others? Does it matter whether or not there are natural kinds? To get an initial feel for the subject let's consider some suggestions from the literature as to what might count as a candidate for a natural kind or natural kind term.

Monist, 2002

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. My main focus in this paper, however, will not be on the nature of biological taxa. The acceptance that biological taxa are not natural kinds has not generally been taken to show that there are no natural kinds in biology. It is just that, on this view, that we must seek them at a more theoretical level than is the concern of applied taxonomy. So although 'Ranunculus repens' or 'Felis leo' may not name a natural kind, perhaps 'species' does. Perhaps the members of Felis leo also belong to a kind of ecology, predators. It has been supposed that the whole lion might instantiate a fundamental natural kind of evolutionary theory, interactor; while tiny little bits of it, lurking at the centre of

2013

The last Tasmanian wolf, a male popularly named "Benjamin," died in captivity in 1936. Thylacinus cynocephalus, the species that Benjamin represented, was soon thereafter declared extinct; however, one may advance the argument that the species was already extinct when the last of Benjamin's conspecifics died, leaving him a member of an extinct species. This raises the "species problem": what, if anything, is a species? Resolution of the species problem is complicated by the fact that species are considered "fundamental units" of biological theories in at least two senses. Species are units of taxonomy: they are the smallest "real" groups into which organisms can be classified. Species are also units of evolution: they are the entities that change over time due to Natural Selection. Following Darwin, philosophers of biology traditionally argue that these units can only be identified if species are nominal entities. More recently, paleontologists suggest that species may be "fundamental units" in a third sense: as units of selection in a higher-order process of differential speciation and extinction. Species selection would therefore have a place in a hierarchy of selection processes. At lower levels of selection, units of selection emerge from former units of evolution due to intrinsic functional integration. If species emerge as units of selection in the same way, then the species that participate in species selection would not be coextensive with units of evolution: since functional integration had broken down within T. cynocephalus, Benjamin would be part of the latter unit, but not the former. Nominal entities are defined by extension, and so—contrary to the received view—species meeting these criteria cannot be nominal entities. I therefore argue that species must be natural kinds if they emerge as units of selection in a hierarchy of selection processes. Given the simultaneous identity of units of selection, units of evolution, and units of taxonomy, I suggest an application of the Kripke/Putnam model of natural kinds that is consistent with the theory of Natural Selection. I also consider a reading of Darwin's work that demonstrates the viability of this model.

2016

Abstract. — The issue of species delimitation has long been confused with that of species conceptualization, leading to a half century of controversy concerning both the definition of the species category and methods for inferring the boundaries and numbers of species. Alternative species concepts agree in treating existence as a separately evolving metapopulation lineage as the primary defining property of the species category, but they disagree in adopting different properties acquired by lineages during the course of divergence (e.g., intrinsic reproductive isolation, diagnosability, monophyly) as secondary defining properties (secondary species criteria). A unified species concept can be achieved by treating existence as a separately evolving metapopulation lineage as the only necessary property of species and the former secondary species criteria as different lines of evidence (operational criteria) relevant to assessing lineage separation. This unified concept of species has s...

Oxford Handbook of the Philosophy of Science, 2015

Science posits entities that are neither individuals nor properties but kinds of individuals that share a number of distinct properties. Philosophers have designated them “natural kinds” and have held different views about how to distinguish them from arbitrary collections of individuals. The doctrine of “kinds” or “natural groups” was first explicitly introduced by nineteenth-century philosophers interested in taxonomy or scientific classification and continues to be the subject of lively debate in contemporary philosophy. After canvassing some of the philosophical controversies regarding natural kinds, the article presents two influential contemporary theories of natural kinds: essentialism and the homeostatic property cluster theory. The article goes on to defend naturalism, which is more in tune with the findings of modern science.

Taxa and homologues can in our view be construed both as kinds and as individuals. However, the conceptualization of taxa as natural kinds in the sense of homeostatic property cluster kinds has been criticized by some systematists, as it seems that even such kinds cannot evolve due to their being homeostatic. We reply by arguing that the treatment of transformational and taxic homologies, respectively, as dynamic and static aspects of the same homeostatic property cluster kind represents a good perspective for supporting the conceptualization of taxa as kinds. The focus on a phenomenon of homology based on causal processes (e.g., connectivity, activity-function, genetics, inheritance, and modularity) and implying relationship with modification yields a notion of natural kinds conforming to the phylogenetic-evolutionary framework. Nevertheless, homeostatic property cluster kinds in taxonomic and evolutionary practice must be rooted in the primacy of epistemological classification (homology as observational properties) over metaphysical generalization (series of transformation and common ancestry as unobservational processes). The perspective of individuating characters exclusively by historical-transformational independence instead of their developmental, structural, and functional independence fails to yield a sufficient practical interplay between theory and observation. Purely ontological and ostensional perspectives in evolution and phylogeny (e.g., an ideographic character concept and PhyloCode’s ‘individualism’ of clades) may be pragmatically contested in the case of urgent issues in biodiversity research, conservation, and systematics.