It has been argued by Hull and others that a remnant of essentialism impeded taxonomic progress until systematists abandoned attempting to define taxa on the basis of characters necessary and sufficient for group membership. The advent of cladistics suggests instead that it is an essentialistic view of characters, not of taxa, that should be abandoned, and that only a transformational view of characters allows evolutionary novelties to be identified, much less explained. Conventional Darwinian explanations are not tautologous but are difficult (...) to test and scarcely explain evolutionary novelties, probably because of their emphasis on genetic rather than epigenetic (developmental) processes. (shrink)

All biologists use classifications to one degree or another, and those of us who work on classifications use the results of all other biologists to one degree or another, so you might reasonably expect that biologists in general would share some common conception of how classifications should be constructed and how they can be used. Certainly one might expect that all taxonomists, at least, would share such a perspective. But this is not the case; in fact, the theory of taxonomy (...) is at present a very controversial subject, with much of the controversy revolving around the question of how to go about constructing an ideal classification.Surprisingly, there is relatively little controversy about what properties an ideal classification would have. Admittedly, different terms are used to describe these properties, various workers arguing that classifications should be maximally stable, or maximally useful, or maximally informative, or maximally testable, or maximally refutable, or maximally predictive, and so on. (shrink)