DARWINISM, PROCESS STRUCTURALISM, AND NATURAL KINDS

Darwinists classify biological traits either by their ancestry (homolo gy) or by their adaptive role. Only the latter can provide traditional natural kinds, but only the former is practicable. Process structural ists exploit this embarrassment to argue for non-Darwinian classificat ions in terms of underlying developmental mechanisms. This new taxonom y will also explain phylogenetic inertia and developmental constraint. I argue that Darwinian homologies are natural kinds despite having hi storical essences and being spatio-temporally restricted. Furthermore, process structuralist explanations of biological form require an unwa rranted assumption about the space of developmental possibility.