Substance As Subject of Change
Aristotle says that substances are able to receive contraries. In fact, the potential to receive contraries is what is “most distinctive of substance” (Catg. 4a10). Consider a table with a white surface, for instance. The whiteness of the table’s surface is known through sensation. When I paint the white surface blue, what changed? It was not the color white, white cannot be anything other than what it is. We see the presence of one color and then we see the presence of another, but the colors themselves cannot be the things that underwent change. The subject of change cannot be color, which is an object of vision, therefore the subject of change was not something that is given to our sense experience. This account can be expanded to include man and all of his accidents. Man undergoes changes in his color yet the colors which he bears do not themselves change. He also can be many different ages, sizes and shapes, etc. The substance “this man,” though, must allow for all of these contraries to subsist in him somehow. As a substance, man is not something that can be explained through recourse to our sensible experience, and this is even true when we point to something and call it “this man.” This is true of all substance as such. On Aristotle’s account, substance is actually something that cannot be seen, smelt, touched, heard, or tasted, yet it accounts for the way we speak of subjects like man, horse, and table.