Page - 180 - in The Priority of Locomotion in Aristotle’s Physics

An animal cannot have the sensory capacity without having the nutritive one, while there are living beings that have the latter without the former.41 The locomotive capacity and the sensory capacity stand in a similar rela- tion: having the former presupposes also having the latter, but not vice versa.42 The relation between these capacities therefore is one of ontological priority. As we have seen in the discussion of the third argument for the priority of locomotion, x is ontologically prior to y, if and only if x can exist without y, but not vice versa. In terms of the three capacities of the soul this means that (1) the locomotive capacity cannot exist without the sensory one, but not vice versa, and (2) the sensory capacity cannot exist without the nutritive one, but not vice versa. Therefore, (3) the locomotive capacity also cannot exist without the nutritive one, but not vice versa. For this reason, all living beings have the nutritive part in common, no matter whether they also have the capacity for sensation or locomotion. However, it is impossible for there to be a living being which has the sen- sory capacity, but does not have the nutritive one. In the same way, it is not possible for there to be a living thing that has locomotion, but lacks percep- tion or nutrition. Accordingly, the different capacities may be ordered in the following way according to their ontological priority: 1. Nutritive capacity 2. Sensory capacity 3. Locomotive capacity As with respect to priority in coming to be, with respect to ontological priority it is also not the capacity for locomotion that is prior to the rest, but the one that is responsible for growth and diminution, i.e. for nutrition. In fact, the capacity to cause one’s own change in place is posterior to the two other relevant capacities in this way. But, as we have seen, the argument is not about showing that the capacity for locomotion has ontological, but that it has essential priority. Aristotle has already shown in the first three arguments that locomotion in general is ontologically prior to the other kinds of change. A result of the third of these arguments (which I discussed in chapter 5 of my work) was that, from a broader perspective, every change in quantity and quality, even if it is self-caused by a living thing’s nutritive 41 See de An. II 3, 415a1–3. 42 See de An. ΙΙΙ 10, 433b27–30, where Aristotle argues that an animal is only capable of locomotion (κινητικόν) insofar as it is capable of desire (ὀρεκτικόν). The latter, again, pre- supposes either the sensory (αἰσθητική) or the reasoning capacity (λογιστική). As only some of the animals have reason, but all of them have desire (see de An. III 11, 434a5–7), and since some of them may move themselves without having reason, it is clear that the locomotive capacity presupposes the sensory one. However, there are animals, for instance sponges, which are capable of sensory activity but not of locomotion. 180 Locomotion is prior in essence ISBN Print: 9783525253069 — ISBN E-Book: 9783647253060 © 2014, Vandenhoeck & Ruprecht GmbH & Co. KG, Göttingen