Aristotle, Plotinus, and Simplicius on the Relation of the Changer to the Changed

The longest continuous discussion of change (kínhsiv) in the Aristotelian corpus is book G of the Physics. There are, of course, many difficult issues raised in this book but, for the purposes of this examination, a summary of Aristotle’s conclusions pertaining to the location of change suffices, and so we can keep our account brief. Aristotle defines change as ‘the actualization of the potential as such’ (h toũ dunámei o ntov e nteléceia, F } toioũton, Phys. G 1, 201a10–11), the meaning of which is best grasped through one of his own examples. A certain collection of boards and bricks is potentially a house in so far as they fulfil the material requirements of a house and can therefore receive the form of house. To actualize this potential is to build a house out of these materials, and so we can say that in this case change is defined as the actualization of these materials’ potential to be a house, that is, it is the process of being built into a house (Phys. G1, 201b5–15). One attractive feature of such an abstract definition of change is its broad applicability. The same definition can be used to account for human acts (kinh́seiv). For example, when a man who knows how to build a house is himself in the process of building a house, this act can be described as the actualization of his potential (that is, his knowledge of how) to build houses. However, as economical as this definition might be, it raises a serious concern: what is the relationship between the change that takes place with respect to the builder—the act of building or the actualization of his potential to build a house—and the change that takes place with respect to the materials—the process of being built into a house or the actualization of their potential to become a house? Aristotle’s response to this concern is too well known to warrant discussion here. It is enough for us to catalogue some of its significant features: