ABSTRACT
Mary Shepherd built a systematic philosophy encompassing metaphysics, epistemology, and the theory of perception. In this chapter, I will focus on Shepherd’s account of knowledge of the external world, along with the theory of causation it relies on. For that purpose, I will discuss Shepherd’s four grounding principles for scientific research and practical knowledge: the causal principle, the causal likeness principle, the uniformity principle, and the principle “like objects, must ever have like qualities.” This chapter will show how Shepherd’s concepts of causation and matter allow her to affirm the existence of a material world that causes our sensations. Shepherd’s conception of matter is quite different from that of her predecessors such as Locke, Clarke, and Newton. They conceived of extension as a categorical property, while she conceives of it as a power. And while they conceived of matter as that which has the categorical property of extension, she conceives of matter too as a power.
