Version: v1, Published online: 1998
Retrieved October 16, 2018, from https://www.rep.routledge.com/articles/biographical/aristotle-384-322-bc/v-1
Aristotle studies nature as an internal principle of change and stability; and so he examines the different types of change (or ‘motion’; kinēsis) that are found in the natural elements and in the natural organisms composed of them. In Physics III 1 he defines change as ‘the actuality of the potential qua potential’. His definition marks the importance of his views on potentiality (or ‘capacity’; dynamis) and actuality (or ‘realization’; energeia or entelecheia) (see Metaphysics IX 1–9).
The primary type of potentiality is a principle (archē) of change and stability. If x has the potentiality F for G, then (1) G is the actuality of F, and (2) x has F because G is the actuality of F. Marathon runners, for instance, have the potentiality to run 26 miles because they have been trained to run this distance; hearts have the capacity to pump blood because this is the function that explains the character of hearts. In these cases, potentialities correspond to final causes.
Potentiality and possibility do not, therefore, imply each other. (1) Not everything that is possible for x realizes a potentiality of x. Perhaps it is possible for us to speak words of Italian (because we recall them from an opera) without having a potentiality to speak Italian (if we have not learnt Italian). (2) Not everything that x is capable of is possible for x; some creatures would still have a potentiality to swim even if their environment lost all its water.
These points about potentiality help to clarify Aristotle’s definition of change. The building of a house is a change because it is the actuality of what is potentially built in so far as it is potentially built. ‘What is potentially built’ refers to the bricks (and so on). The completed house is their complete actuality, and when it is reached, their potentiality to be built is lost. The process of building is their actuality in so far as they are potentially built. ‘In so far…’ picks out the incomplete actuality that is present only as long as the potentiality to be built (lost in the completed house) is still present. Aristotle’s definition picks out the kind of actuality that is to be identified with change, by appealing to some prior understanding of potentiality and actuality, which in turn rests on an understanding of final causation.
In the rest of the Physics, Aristotle explores different properties of change in relation to place and time. He discusses infinity and continuity at length, arguing that both change and time are infinitely divisible. He tries to show that the relevant type of infinity can be defined by reference to potentiality, so as to avoid self-contradiction, paradox or metaphysical extravagance. In his view, infinite divisibility requires a series that can always be continued, but does not require the actual existence of an infinitely long series. Once again, the reference to potentiality (in ‘can always…ȁ) has a crucial explanatory role.
Irwin, T.H.. Change. Aristotle (384–322 BC), 1998, doi:10.4324/9780415249126-A022-1. Routledge Encyclopedia of Philosophy, Taylor and Francis, https://www.rep.routledge.com/articles/biographical/aristotle-384-322-bc/v-1/sections/change.
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