In this paper, I compare Margaret Cavendish’s argument for the view that colours of objects are inseparable from their ‘physical’ qualities with George Berkeley’s argument for the view that secondary qualities of objects are inseparable from their primary qualities. By reconstructing their respective arguments, I show that both thinkers rely on the ‘inconceivability principle’: the claim that inconceivability entails impossibility. That is, both premise their arguments on the claim that it is impossible to conceive of an object that has size (...) and shape but no colour. I argue that Cavendish, like Berkeley, accepts the inconceivability principle on the grounds that it is impossible to conceive of something that could not, in principle, be perceived and, in turn, that something imperceptible could not possibly exist. As such, I argue that both Cavendish and Berkeley are committed to an ‘empiricist’ modal epistemology: one wherein our knowledge of what it is possible to perceive informs us about what could possibly exist. For this reason, I conclude that there is more empiricism in Cavendish’s epistemology than secondary literature to date suggests. (shrink)

An understanding of the precise nature of the scientific method of Sir William Petty has proved elusive to historians of economic thought, in no small part because of a lack of Petty's own characterization of his scientific approach. This research clarifies the nature of Petty's method, as to whether it was primarily inductive or deductive, and to what extent it relied on empirical foundations. The paper employs a two-pronged analysis. First, it examines the main sources of Petty's method: the works (...) of Sir Francis Bacon and Thomas Hobbes, and the synergistic influences of the Hartlib Circle, the Royal Society, the Dublin Philosophical Society, and the Mersenne group. Second, four of Petty's most noted contributions to political economy are deconstructed in order to identify his scientific method. This research concludes that Petty relied almost exclusively on deduction in his scientific approach and that his analysis does not reveal any inductive reasoning. When data was available, Petty constructed his economic theories on empirical foundations. (shrink)