Plato and Aristotle on the Aims and Value of Division

Disputes about ground and fundamentality are connected to a cluster of questions about essences, definitions, explanation, priority, and knowledge. Aristotle and Plato of course disagree on a number of these issues, but one of the least understood concerns the nature and value of “division,” i.e. seeking an account of something by successive divisions of a higher genus. Plato introduces his method of “collection and division” in especially grand terms—doing it successfully appears to be one of our highest intellectual achievements, and a necessary means to understanding the real natures of fundamental kinds. Aristotle disputes the methods of Platonic division, but he thinks they have overestimated its epistemological value. Plato’s reasons for assigning division such high value are not always clear, but nor are Aristotle’s reasons for skepticism. As in recent disputes about the nature of ground, there is an underlying concern with working out what appear to be metaphysically important and broadly explanatory relationships which are not causal in the standard sense, and their relationship to philosophical and scientific aims of giving essence-specifying definitions. Re-evaluating their disagreement about definition-by-division thus promises to clarify their views on this cluster of topics as well as their connection to modern debates.