Locke’s Confusion About the Confused Idea of Substance

Substance is the name philosophers give to the category of things as opposed to their properties. Theorizing about substance played a major role in the development of philosophy in the early modern period. John Locke offered a view of substance that caused philosophical and theological concern in his day and continues to perplex those who study his writings. Locke derisively compared substance to an elephant that holds up the world, and he referred to substance as “a supposed, I know not what”. Despite this, he believed in the existence of substances, and he explained how the idea of substance in general is used by the mind to frame representations of them. In my dissertation, I argue that Locke’s doctrine of substance has proven difficult to understand because it defies two ubiquitous interpretive assumptions: (i) Locke is a Humean empiricist; and (ii) Locke’s account contains no degree of confusion. I make the case that it is not possible to make sense of what Locke said while holding onto these assumptions. According to my reading, (i) Locke permitted mental representations with intelligible content. These ideas are generated by the understanding. However, (ii) Locke displayed a tendency to treat all ideas as if they were capable of being distinctly imagined. This is problematic because intelligible content is not registered in the imagination. On the basis of this, Locke concluded that certain ideas with intelligible content are confused perceptions. The idea of substance in general is one such idea. Locke believed the idea of substance could provide no insight into the nature of substances because it appeared to him to be a confused perception. In fact, it cannot do that because it is a mere idea of reason. Even if we knew the real essences of natural things, the idea of substance in general—the idea of a common subject—would remain impervious to distinct imagination.