Is 'Natural Kind' a Natural Kind Term?

Abstract

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 the paper, however, will not be on the nature of bi ological 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, we must seek them at a more theoretical level than is the concern of applied taxonomy. So although 'Ranunculus repens9 or 'Felis leo9 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 each of its cells, might be members of the kind, replicator. And surely these little bits at least belong to kinds of organic chemistry. Perhaps grosser parts of the lion may instantiate kinds such as liver, heart, or teeth. And so on.