Page - 207 - in The Priority of Locomotion in Aristotle’s Physics

7.3 Conclusion: Locomotion’s priority in essence Now that we have seen that Aristotle is correct in claiming that locomotion has this special status, since locomotion alone cannot make its subject’s essence change in the manner in question, but rather preserves it comple- tely, it remains to explain in what way this is a reason for locomotion’s priority in essence (κατ᾽ οὐσίαν). The first of the two arguments for essential priority showed that locomo- tion is prior in essence for perishable living things. The second argument, as I will make clear now, presents reasons why locomotion is also prior in essence with respect to eternal things that at least in principle can undergo some kind of change. The two arguments taken together then show that locomotion is prior in essence for perishable living things as well as for eter- nal things, that is, with respect to all things (apart from the unmoved mover) that are responsible for the changes that occur in the universe.86 That locomotion is prior in essence for living things was shown by Aristotle by making use of the reversed priority claim and the fact that locomotion comes last to perishable things in their development. As I have shown, this means that it is more specific to x for it to have locomotion than alteration or growth and diminution. Having the capacity to self-locomote makes an animal more what it is than alteration or growth and diminution. It is more specific to x as a member of a certain species to have locomotion. But how does this connect to the second argument for priority in essence? This argument rather appears to be about change in place in gen- eral than about locomotion being more specific to something x than any of the other kinds of change. The reason why locomotion has priority in essence seems to be that of the four kinds of change it makes its subject “depart from its essence the least” (ἥκιστα τῆς οὐσίας ἐξίσταται), i.e. preserves the essence best. On this understanding, the better a change pre- serves its subject’s essence, the more priority it has in essence. This may be a possible reading of our passage. But this understanding becomes proble- matic when we remember that the argument I just discussed is only one of two arguments that are supposed to demonstrate that locomotion has pri- macy in the same way, namely in essence (κατ᾽ οὐσίαν). Therefore, in order to avoid assuming that Aristotle makes the mistake of equivocating two in fact different ways in which a change can have priority in essence, one should presuppose that the understanding of priority in essence under- 86 As I pointed out in section 3.4, p.57f. (n.51), Aristotle in MA 6, 700b11–12, clearly states that all changes are either caused by living beings or by sources of change from the superlunary sphere, i.e. by things that are eternal. Conclusion: Locomotion’s priority in essence 207 ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen