Species Names in the Age of Discordance

In this paper I propose an alternative to the causal-historical theory of reference for species names, an account which has been hegemonic in the literature ever since Ghiselin and Hull presented it as a consequence of their species-as-individuals thesis. Recently, causal-historicism has revived its Kripkean essentialist roots, with the work of so-called “new essentialist” philosophers such as Ellis, LaPorte and Okasha. I argue that, in order for an essentialist causal-historical theory of reference to work, species should be constituted of strictly monophyletic lineages. But, to put things in terms of Haber's (2012) concept of multilevel lineages, as a matter of fact monophyly often fails to hold at several of the lineage levels that are part of any given species. Thus, I wish to defend an antirealist theory of reference for species names that takes genealogical discordance into account. Since my account draws from the concepts of “criterion of application” and “criterion of identity” put forth by Dummett in his study of Frege, I will call it the Frege-Dummettian (FD) theory. According to the FD account, species names refer to the resultant of the sum of a criterion of application, provided by a formal code of nomenclature, and a criterion of identity, typically presented in the form of a species concept. However, most phylogenetic studies are published without any clear statement of the relevant species concept being assumed by their authors. This leads to a situation in which the criteria of identity for a name, and ultimately reference itself, ends up being radically context-sensitive. The upshot is that a species name is perhaps best understood as the name of a family of scientific models or hypotheses, each attempting to describe a certain aspect of the multilevel, often discordant, lineage that is the species itself. In conclusion, I suggest three applications of the FD account: in the discussion of polar and brown bear phylogenies, in the misidentification of type specimen example suggested by Haber (2012), and in the debate about the theory-ladenness of the PhyloCode.