The Illogical Basis of Phylogenetic Nomenclature

The current advocacy for the so-called PhyloCode has a history rooted in twentieth-century arguments among biologists and philosophers regarding a putative distinction between classes and individuals. From this seemingly simple and innocuous discussion have come supposed distinctions between definitions and diagnosis, classification and systematization, and now Linnaean and “phylogenetic” nomenclature. Nevertheless, the metaphysical dichotomy of class versus individual, insofar as its standard applications to the issue of biological taxonomy are concerned, is an outdated remnant of early logical positivist thinking. Current views on natural kinds and their definitions under a scientific realist perspective provide grounds for rejecting the class versus individual dichotomy altogether insofar as biological entities are concerned. We review the role of natural kinds in scientific practice and the nature of definitions and scientific classifications. Although inherent instabilities of the PhyloCode are clearly sufficient to argue against the general application of this nominally phylogenetic system, our goal here is to address serious and fundamental flaws in its very foundation by exposing the unsubstantiated philosophical assumptions preceding and subtending it.