Page - 217 - in The Priority of Locomotion in Aristotle’s Physics

one, is at the same time the weakest kind of change in another respect, i.e. change in place. For only locomotion leaves its subject’s essence completely untouched and is of such a nature that it can be engaged in eternally with- out thereby posing any threat to its subject’s essence. In contrast to change in quality and quantity, which would entail their subject’s corruption, if they carried on without limit—not to speak of generation and corruption— locomotion does not affect its subject’s being in any way and therefore not even in principle does it entail any substantial change. Thus, if there were no such change as locomotion, then Aristotle’s causal explanation of change in the cosmos would collapse. In the sense at issue, change in place is both the only, and at the same time the ideal, candidate for the change that has its direct source in the first principle of all change, the first unmoved mover, and that the outermost sphere and the other eternal heavenly bodies always have been and always will be undergoing. But one needs to be clear about the fact that Aristotle in the discussion stated in Phys. VIII 7 certainly is not aiming at presenting a deductive proof for the claim that the kind of change which has its direct source in the first unmoved mover can only be locomotion. Rather, Aristotle here is giving reasons that help us understand why this is the case and how this fits with empirical facts and our assumptions about the cosmos. This, however, is absolutely appropriate for a dialectical inquiry, which is what the discussion in Phys. VIII 7 should be considered. For, as I stated in the introductory part of my investigation, Book VIII, as a part of the Physics lays out the fun- damental principles of the science of nature that do not admit of proof. This is exactly what Aristotle is doing in Phys. VIII when he spells out the impli- cations of there being change in the cosmos, and in so doing shows that, first of all, change must exist eternally, that all changes in the cosmos may be traced back to a first principle of change, i.e. the first unmoved mover, and that the change primarily caused by this first source is a special kind of locomotion. Although showing that locomotion is the primary kind of change is an essential part of providing the needed justification for the claim on which the theory developed in Phys. VIII 1–6 is based, this task as a whole is not completed after the presentation of the five arguments. For, in order to complete it, two more steps are necessary. First, Aristotle still needs to show that an eternal change is at all possible, and which kind of change this could be. I have presented parts of this discussion, which is stated in Phys. VIII 7– 8 (261a28–265a12), since the last of the three arguments for locomotion’s ontological priority, as we have seen, presupposes that there is a kind of change that may form one single non-composed change that is eternal. Aristotle shows that this change can only be a special kind of locomotion, namely circular locomotion. Therefore, in order to make sure that the one single change which is eternal is also the one which is primary, i.e. fulfils Conclusion 217 ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen