Seite - 171 - in The Priority of Locomotion in Aristotle’s Physics

According to my definition of priority in essence, only individual sub- stances can be substituted for x and y. Essential priority, therefore, seems to be a relation between substances. This is also what is suggested by the examples mentioned in Met. IX 8, where such individuals are compared with respect to the fulfilment of their respective form: the man is prior to the boy, as the human being is to the seed; since man and human being are fulfilling their form, they are complete with respect to their essence. But, as the application of the reversed priority claim in the passages from Met. IX 8 and from Phys. VIII 7 also show, not only individual things can be called prior in essence, but also states and features of those individuals—after all, the one passage argues for the claim that locomotion is prior in essence to the other kinds of change, while the other that ἐνέργεια has priority in essence over δύναμις.12 But for Aristotle ‘locomotion’ certainly is not something one could call a substance or an individual and which accord- ingly could be substituted for one of the variables in the definition of prior- ity in essence. This, however, is not a problem. Something x is called prior in essence to y when it fulfils the form that is common to x and y to a higher degree and has more of the respective essen- tial features than y. That is to say that x is prior to y in having at least one additional essential feature that y does not have. In the coming to be of liv- ing things, each of the features, however, corresponds to a specific stage of development at which it is acquired by the living thing as a member of a natural kind. Because of this fact the feature may be compared to other such features. According to Aristotle, for instance, a living being acquires the fea- ture of locomotion later than, say, alteration, namely at a stage at which it is about to reach its completion.13 Thus, in this respect locomotion—qua spe- cifically belonging to a nearly complete being—is prior in essence to altera- tion, which individuals of the same kind that are less developed already pos- ses. Accordingly, I hold that the relation of essential priority applies primarily to individual substances and in a derivative sense to essential features or attributes, even though whether x is prior in essence to y depends on which of those features x has. Hence, there is no problem in saying that certain features have priority in essence over other ones, and therefore Aristotle is justified in calling locomotion prior in essence to the other kinds of change. As we have seen, Aristotle presupposes that there is an unvarying order of developmental stages through which every member of a certain kind k has to pass step by step in order to reach the endpoint of its development and become a full member of k. As Aristotle points out, the more some- thing proceeds towards the principle of development, i.e. its endpoint, the 12 See Met. IX 8, 1049b4–5. 13 See Phys. VIII 7, 261a15–17. Locomotion is prior in essence, since it is last in coming to be 171 ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen