Newton began his Principia with three Axiomata sive Leges Motus. We offer an interpretation of Newton’s dual label and investigate two tensions inherent in his account of laws. The first arises from the juxtaposition of Newton’s confidence in the certainty of his laws and his commitment to their variability and contingency. The second arises because Newton ascribes fundamental status both to the laws and to the bodies and forces they govern. We argue the first is resolvable, but the second is (...) not. However, the second tension shows that Newton conceives laws as formal causes of bodies and forces. This neo-Aristotelian conception goes missing in Kantian accounts of laws, as well as accounts that stress laws’ grounding in powers and capacities. (shrink)

From late 1684 through mid-1685, Isaac Newton turned to developing and refining the conceptual foundations presupposed by his emerging physics. Analysis of his manuscripts from this period reveals that Newton’s understanding of the relativity of acceleration led him to seek a spatiotemporally invariant quantity of matter. He found two such quantities and then designed an experiment to discover their relationship. Interpreting the experiment, however, required distinguishing a new notion of force. Others have recognized the conceptual distinction between inertial and gravitational (...) mass. I show here that Newton clearly saw this distinction and that he provisionally established their equivalence. (shrink)

In the past, experts have disagreed about whether Samuel Clarke accepted the idea that gravity is a power superadded to matter by God. Most scholars now agree that Clarke did not support superaddition. But the argumentation employed by Clarke to reject superaddition has not been studied before in detail. In this paper, I explicate Clarke's argumentation by relating it to an important discussion about the possibility of superadded gravity in the Clarke-Collins correspondence. I examine Clarke's responses to Collins and draw (...) on his other works to reconstruct Clarke's reasons for rejecting superadded gravity. (shrink)