Introduction: Special Issue on Powers and Essences

Abstract

The natural world, as Latin medieval Aristotelians see it, is a dynamic place.* Material substances are endowed with real active and passive powers or potencies (potentiae), which enable them to produce and undergo changes, respectively. For example, according to medieval thinkers, if a fire burns a log of wood, this occurs due to the log’s passive power of combustibility as well as the fire’s active power of heat. These natural powers, scholastic philosophers hold, are present in virtue of the very essences (essentiae) of their bearers, that is, in virtue of those features that make their bearers the kinds of things they are. Fire’s active power of heat, for instance, follows from the very nature of fire, and the combustibility of wood derives from its essence. How are we to understand these essences that empower material substances? Most Latin medieval Aristotelians conceive of them hylomorphically.1 On their account, the essence of a material substance, be it inanimate or animate, involves two different types of components: matter and at least one substantial form, though some medieval thinkers countenance more than one such form.2 Very roughly, a substance’s matter accounts for its being a material substance, while its substantial form(s) account(s) for its being the specific kind of material substance it is, say, a piece of wood or a cat. According to medieval Aristotelians, both types of components are intimately connected with powers, but with different ones. Matter has a power or potency (the latter term being more commonly used in the secondary