Classification was the traditional framework for most results in biology, and it still plays an important role in that regard. This week we will be looking at two philosophical issues that arise in connection with biological classification.

The second part of Okasha’s ch. 6 concerns one of these. He addresses the specific form it took in biology a decade or so ago, as a dispute between supporters of “phenetics” and “cladistics,” but you should think also of a broader issue of which this is a special case. We can ask in any case where classification is employed in science, whether the basis for the classification should be observable characteristics or features that play a role in underlying theory.

Part of the reason for considering the more general question is that the specific issue in biology, while still discussed, is less clear than it used to be. The traditional approach to classification was not quite either phenetics or cladistics. Those two views arose along with use the computers in construction of phylogenetic trees and a decision was needed about the sorts of programs that would be used. With further development of computer technology the choices are less clear cut and less constraining than they once were, and the dispute between phenetics and cladistics has lost some of its force. But, even if it becomes a historical curiosity to biologists, it is of interest philosophically because it focuses attention on the arguments for using one or the other sort of feature in classification generally.