SPA Seminar Series: Dr Kirsten Walsh (University of Exeter) - "Newton’s Metaphysics in Practice"

In his methodological statements, Newton (in)famously declared ‘hypotheses non fingo’ and explicitly eschewed metaphysical speculation. However, every edition of the Opticks and Principia contains hypotheses and metaphysical speculation. Newton’s commentators thus face a dilemma: they can take Newton’s metaphysical speculations seriously, but this involves downplaying the sincerity of his methodological claims; or they can take his methodological claims seriously, and downplay the significance of his metaphysical speculations. In this paper, I offer a solution to the dilemma: study Newton’s metaphysics in practice. That is, focus on the role of Newton’s metaphysical discussions, constructs and commitments in the context of his scientific work. What we find is that Newton’s metaphysical speculation plays a vital supportive function in his experimental philosophy. Recognising this feature of Newton’s work is revelatory, both of Newton’s methodology