Abstract

It has been claimed that in a single line of development the science of taxonomy stretches from Aristotle to the present day and that the Aristotelian 'essence' lies at the heart of much later thought about grouping. I try to establish some basic features of Aristotle's conception of 'essence', and then consider in more detail the conception of essence that entered into 18th century thought about classification, with a view to establishing discontinuities. 18th century thought, I note, has two kinds of essence, real and nominal, and I consider the view that a 'natural' classification in that context should be understood as one which is based on real essences. In place of this thesis, I advocate the view that the hidden foundation of 18th century systematics is a very restrictive articulation of the visual field which gives sense to the possibility of grouping according to the sum total of observable similarities and differences: and that it is this possibility that a 'natural' classification was conceived of as realising