ABSTRACT
This chapter focuses on the relationship between a philosophical theory of natural kinds and the taxonomic tree, or the conceptual divisions between hierarchical levels of biological classification. The consensus among philosophers is that to affirm biological natural kind essentialism is to be committed to the claim that taxonomy recapitulates ontology—that is, that the branching of the taxonomic tree is shaped by, and thus fundamentally reflects, the ontological architecture of the natural world. As a great deal of the contemporary animosity toward that theory is based on the rejection of this claim, this chapter discusses two problems: the threat of conceptual pluralism—that the categorisation of biological entities is merely heuristic, rather than ontological—and the threat of extrinsicality—that organisms belong to those categories in virtue of their extrinsic, rather than their intrinsic properties. Because the debate about the theory of biological natural kind essentialism is today mostly focused on the ‘species’ category, this chapter discusses the most prominent species concepts—the phylogenetic, environmental niche, and interbreeding concepts—and their relation to and implications for that theory. The central argument of this chapter is that conceptual connection between the ontology of biological natural kind essentialism and the hierarchical architecture of evolutionary taxonomies is not only much more tenuous than is commonly supposed, but is in fact founded on a fundamental mistake—the centrality of causal powers and the corresponding conflation of telos and taxon.
