Essence, Existence, and Nominal Definition in Aristotle's Posterior Analytics II 8-10

Abstract

Our aim in this paper is to clarify the various things Aristotle says about nominal definitions in Book II of the Posterior Analytics. In the early chapters of Book II Aristotle develops a series of puzzles concerning the nature of definition and its relationship to scientific demonstration. In chapters 8-10 answers to the puzzles are given in the course of a positive account of the different types of definitions and how they are related to Aristotle's theory of the syllogism and scientific demonstration. At the beginning of the constructive discussion in chapter 8, Aristotle implies that some of the views expressed in the earlier chapters were not well said, but he does not indicate which specific views need to be rejected or modified. An adequate account of the discussion of definition in Book II would need to show how the constructive chapters are related to the earlier aporetic chapters, and also how this overall discussion fits into Aristotle's general theory of scientific knowledge and scientific investigation. Our task, as we see it, is an important preliminary to this larger project. We will concentrate on chapters 8-10, and specifically on what is said about the different kinds of definition. Questions about Aristotle's theory of science and scientific investigation will come up along the way, but they will be discussed only insofar as they are related to the different kinds of definition. We will also make a few suggestions about specific modifications and corrections introduced in chapters 8-10, but we will not attempt a general account of the relationship between these chapters and the earlier aporetic discussion. Our discussion will contain three main parts. We will first try to determine which passages in chapters 8-10 provide information about nominal definition, and then give a preliminary characterization of this kind of definition. In the next stage we will focus on questions concerning the relationship between nominal definitions and the existence of the things defined. Finally, we will examine the relationship between nominal and