Margaret Cavendish (1623-1673) was an English natural philosopher. Influenced by Hobbes and by ancient Stoicism, she held that the created, natural world is purely material; there are no incorporeal substances that causally affect the world in the course of nature. However, she parts company with Hobbes and sides with the Stoics in rejecting a particulate theory of matter. Instead, she holds that matter is a continuum. She rejects the mechanical philosophy's account of the essence of matter as simply extension. For Cavendish, matter is also essentially living, sensing, and rational. She also rejects the mechanical philosophy's explanation of change solely in terms of transference of motion. Her own explanation of change relies upon a notion of "occasional cause." This paper argues that Cavendish's occasional causes are not to be confused with those of Malebranche; hers have some efficient causal powers. It traces the concept of an occasional cause from the ancient Stoics, through Galen, to Renaissance natural philosophers such as J. B. van Helmont, and ultimately to Cavendish and to Descartes. Thus, the aim of the paper is to explicate Cavendish's non-mechanical model of natural change and to show how the key concept in this model, that of "occasional cause," has a long philosophical pedigree.
