Tuesday, 19 October 2010
Causal Language and the Structure of Force in Newton’s Treatise
Postdoctoral Fellow (CPS)
University at Buffalo, SUNY
12:05 pm, 817R Cathedral of Learning
Abstract: Newton’s Treatise contains an intriguing description of the gravitational force, one that casts the force as arising from ‘the universal nature of matter’ and as having its ‘double cause’ in the ‘dispositions’ of bodies.
Although Newton elsewhere famously denied knowing gravity’s cause, this language seems to suggest a causal hypothesis—one which holds matter capable of acting robustly and at a distance, without any intervening medium, and which even takes the dispositions producing the force to belong to matter’s nature or essence. For what could Newton intend with such language, if not a causal hypothesis? Despite the initial plausibility of this interpretation, I show that it cannot be sustained.
It requires that the robust sense of activity operative in Query 31 be identical to the sense that matter possesses through its vis inertiae in Definition 3. Yet these turn out to be very different sorts of activity.
A close reading of the Treatise passages then reveals that Newton’s remarks all serve to establish universal gravitation and to explain the force’s structure. They do not advance any causal hypothesis at all, and however paradoxical it may seem, his remarks employing causal terms actually describe a mathematical way of considering the force.