Aristotle on Metaphysics(2004) - Bibotu.com

suppose that the essence of Socrates is being human; then evidentlySocrates will be human for as long as he exists. Or suppose that the essenceof water is H 2 O; then evidently water will be H 2 O for as long as it exists.So, in general, if E is the essence of a thing, x, then x will be, withoutchange or variation, E for as long as it exists. It is in just this sense that theessence of a thing is something changeless.However, the claim that essences are changeless can be understood intwo ways. It may be understood to mean that the essence, E, is changelessand everlasting. This will be the natural way to understand it, if one thinks,as does Plato, that the essence is separate and distinct from changingthings. On the other hand, it may be understood to mean that the essence,E, is changeless but not everlasting. This will be the natural way tounderstand it, if one thinks, as does <strong>Aristotle</strong>, that the essence isinseparable from the changing, material thing whose essence it is. So Platothinks that essences are changeless, and he thinks that:PL11. Essences are everlasting.Finally, Plato thinks that:PL12. Forms and essences are universals.CRITICISM OF PLATO’S THEORY OF FORMS 309Forms are universals at least in the following sense: many differentchanging things can participate in one and the same form. In other words,one and the same form can be true of many different changing things. Somuch by way of summary of Plato’s theory of forms.<strong>Aristotle</strong> rejects Plato’s theory of forms. To begin with, he rejects whatappears to be the basic motivation behind this theory, i.e. the view that senseperceptibleand in general changing things do not have an essence and donot have any determinate features in virtue of themselves. He argues thatchanging things, the things that make up what he calls ‘nature’ (phusis),have changeless essences; and they have changeless essences in spite of thefact that they are changing. Indeed, he argues that a particular changingthing (e.g. Socrates), in the sense of the ultimate subject of predication andthe particular that this thing is, is identical with its changeless essence (seeChapter 7§§5v and vi). So he argues that there is no reason to postulatethe existence of essences as Plato conceives of them, i.e. as separate anddistinct from changing things. He also argues that the essence of aparticular changing thing is not a universal; for it is identical with theultimate subject of predication, which is a particular (see Chapter 7§§5v,viii and ix). Finally, he argues that Plato’s theory of essences as separate and