Much has been written on Newton’s concept of matter, as well as Newton’s laws. Meanwhile, the metaphysical and epistemological relationships between these two principal features of Newtonian philosophy are relatively unexplored. Among the existing accounts of the relationship between bodies and laws, two are especially compelling: the “law-constitutive” approach from Katherine Brading and the “formal-cause” approach from Zvi Biener and Eric Schliesser. Both accounts argue that Newton’s bodies are (at least partially) metaphysically dependent on the laws. That is, according to (...) Brading, Biener, and Schliesser, Newtonian laws are ontologically prior to the bodies they govern. In this article, I reply to Brading, Biener, and Schliesser. I develop negative arguments against their approaches by closely examining three features of Newton’s ontology—forms, particles, and active principles—and their relationship to the laws. I also offer an explanation as to why “law-first” approaches have (understandably) dominated recent Newtonian exegesis. Finally, I present a positive argument for what I believe to be a superior alternative: Newton’s law-first approach is purely pragmatic. It is a feature of his experimental philosophy that we should begin our inquiry into the metaphysical constituents of the universe with the laws that arise from them. This does not entail, however, that Newton views laws as constituting or forming physical bodies. Newton’s metaphysics should be interpreted as “matter-first,” with bodies giving rise to laws, whereas his epistemology should be interpreted as “law-first,” with knowledge of laws giving rise to knowledge of bodies. (shrink)

Making a history of the principle of inertia, as of any other principle or concept, is a complex but still possible operation. In this work it has been chosen to make a back story which seemed the most natural way for a reconstruction. On the way back, it has been decided to stop at the 6th century CE with the contribution of Ioannes Philoponus. The principle he stated, although very different from the modern one, is certainly associated with it. Going (...) back in time it is still possible and of course one could proceed to the origins of the homo sapiens who perhaps posed the problem of why a club thrown with his hand could go so far from him. But the similarities that one can find with the modern principle are very vague, too perhaps. Without going so far one could see an embryonic idea of the principle of inertia in the atomistic theory of Democritus in the 5th century BCE. The motion of atoms whirling with no apparent reason can suggest the idea that a body can also move with no reason. But the transition from the atom, a metaphysical being, to the body, an empirical being, is far from immediate. (shrink)