Aquinas: Substance and Accidents

Terence Nichols recently pointed to three examples from modern science that seem to refute Aquinas’ doctrine of the unicity of substantial form: water in man, organ transplants, and the genetic material received from one’s parents. These examples are intended to demonstrate the quasi-independent existence of parts from the substantial form of the whole. Nichols proposes modifying Aquinas’s hylomorphism by adding a third category of form, which can be called subsidiary forms, subsidiary wholes, or holons. In simpler terms, a holon is (...) a semi-autonomous whole within a larger whole. Nichols’ overall argument suggests that we revise Thomistic metaphysics to account for these scientific findings. I argue that Nichols’ suggestion is unwarranted for two reasons. First, Aquinas argues that holons are a logical impossibility within his metaphysical framework. Second, while Nichols rejects the virtual presence of forms, this does not demonstrate a failure of the Thomistic account of substances within larger wholes. (shrink)

I argue that Thomas Aquinas maintains the view that powers are accidental to their bearers not because powers pertain to bearers with limited essences, but because their bearers have limited actual being. Power tracks not only the essence of something but also its actual existence. Things have powers that are causally relevant when these things exist, that is, the nature of a power is determined by a thing’s essence, but the actual being of the thing of that essence accounts for (...) the limitations of this power and for the extent to which a power can have causal effects.J’interroge dans ce travail le sens dans lequel Thomas d’Aquin estime que les choses dotées de pouvoirs possèdent ceux-ci de manière accidentelle. Cette prise de position s’explique parce que le pouvoir retrace l’existence réelle d’une chose en plus de son essence. Les choses ont des pouvoirs pertinents à l’ordre de la causalité lorsque ces choses-là existent : la nature d’un pouvoir est déterminée par l’essence d’une chose, tandis que l’existence même de la chose ayant cette essence explique les limites de ce pouvoir et la mesure dans laquelle une puissance peut être cause d’effets. (shrink)