Species, Determinates and Natural Kinds

Abstract

1. In an article appearing in this Journal,2 John Woods offers an account of certain classificatory notions. His analysis uses a familiar technique: presentation of a truth-functional definition, which is then modified in an ad hoc manner to meet various counterexamples. In recent years, the fruits of this technique have been subjected to criticism of the most devastating sort. Woods' proposals are no exception to this, and in fact abound in crippling flaws. Below, I will list some of these, paying most attention to his account of the relation of species to genus. In a concluding section I will make some suggestions concerning a more suitable approach to these problems. 2. Woods' analysis of the determinate-determinable relation suffers from the defect that Fx is a determinate of Gx, then Gx is a theorem of the predicate calculus. This follows at once from his condition 2*), which is built into all his later reformulations. According to 2*), Fx is a determinate of Gx then if there is a third term Px, distinct from Fx and Gx, such that (Gx Px) entails Fx, then Px entails Gx and Px entails Fx.3 Where Fx and Gx are any terms, let Px be ( .-Gx V Fx). Clearly, (.. Gx V Fx) is distinct from both Gx and Fx, and (Gx Px) F--Fx.4 However, Px H--Gx