Seite - 170 - in The Priority of Locomotion in Aristotle’s Physics

to pass in order to reach its specific endpoint and in which order this takes place.11 Every male human being roughly speaking originates from a seed, develops into an embryo, then into a boy before finally becoming a full- grown man, and there is a set of attributes that is specific to each of these stages. This means that x and y (both coming to be members of a kind k) in their development towards being full members of k acquire the attributes essential for being k in exactly the same order. Thus, if x and y are of the same priority in essence, then both are at the same stage of development and therefore have identical sets of essential attributes. If x is prior in essence to y, it has completed more of the steps necessary to become k than y, and thus fulfils k’s essence to a higher degree than y. The more develop- mental stages something passes through, the more essential attributes it acquires, attributes that are characteristic for its belonging to a certain kind. What this basically means is that x is essentially prior to y, if x fulfils their common essence to a higher degree than y. On this understanding, a defini- tion of priority in essence would read as follows: PRIORITY IN ESSENCE: Of two things x and y, both individuals of one and the same kind k, x is prior in essence to y relative to k, iff x fulfils the essence of k to a higher degree than y. Applying this to the cases discussed so far, namely for things that have a coming to be, this means that of two living things x and y, both belonging to kind k, x is prior in essence to y relative to k, if and only if x has more of the essential attributes of k that are acquired in a k-specific order than y. One might think that the reference to fulfilment of essence in the definition implies that essential priority applies only to things that have a coming to be, i.e. a process in which the essential features are acquired step by step. In fact, the reversed priority claim explicitly limits its scope to things that have a coming to be, i.e. perishables. This, however, is not a sufficient reason to assume that the relation of priority in essence has the same scope. In my view, priority in essence is not restricted to things that have a coming to be, but, as I will argue later on also applies—at least in principle—to eternal things. The reversed priority claim follows from the account of priority in essence and the fact that there is an unvarying order of coming to be that must be followed by the living things that undergo such a process. It is not a definition of essential priority in terms of coming to be, but rather a corol- lary. Yet, in the two texts I have examined this claim is central to under- standing what priority in essence is, as the texts do not say anything more explicit about essential priority than what is stated in the quoted passages. 11 That Aristotle assumes there to be a specific order of development that is determined by what the thing is becomes clear in PA I 1, 640b1–4 as well, where this is pointed out expli- citly. 170 Locomotion is prior in essence ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen