Andrew Janiak: Three Concepts of Cause in Newton's Thought

The paragraph discusses the early modern era's mechanist philosophers like Galileo, Descartes, and Boyle, who criticized the scholasticism of their time for relying too heavily on common beliefs about perception and causation. They advocated for a view based on the properties of particles and efficient causal relations. Newton, influenced by these thinkers, initially aligned with their anti-Scholastic and anti-Aristotelian views but later introduced concepts in his 'Principia Mathematica' that deviated from strict mechanist philosophy, such as the definition of mass and the concept of impressed forces like gravity, which were not tied to contact action.

This paragraph delves into the complexities of Newton's relationship with mechanist philosophy, particularly concerning the concept of causation. While Newton's early work seemed to support the mechanist view that natural phenomena could be reduced to contact actions between material bodies, his later definitions, especially of 'impressed force,' expanded the concept to include actions at a distance, such as gravity. This shift presented a challenge to the mechanist understanding of causation, which relied on direct contact and tangible interactions between bodies.

The speaker explores Newton's reinterpretation of mechanical causation, suggesting that Newton moved away from the traditional mechanist view that causation is solely due to contact action between material bodies. Instead, Newton proposed that forces, such as gravity, could act as impressed forces at a distance, challenging the mechanist notion that all change must occur through the impacts of material bodies. This idea was not universally accepted among mechanists, some of whom were uncomfortable with attributing dynamical properties like resistance to acceleration to material objects.

The paragraph examines Newton's introduction of centripetal forces, such as gravity, as a species of impressed force. This concept was initially at odds with the mechanist view, which required contact between bodies for causation. Newton's examples of centripetal forces, including gravity, magnetism, and the force maintaining planetary orbits, suggested a broader understanding of causation that could occur over vast distances without direct contact. This expansion of the causal realm beyond mechanical impacts was seen as problematic by some mechanists and indicated a departure from traditional mechanist principles.

The speaker discusses Newton's complex stance on causation, highlighting his rejection of the mechanist view that all natural change occurs through the impacts of material bodies. Newton proposed that causation could extend beyond mechanical impacts, suggesting that forces like gravity could be instances of non-mechanical causation. Furthermore, he introduced the concept of agent causation, which has roots in medieval thought and implies a traditional metaphysics of substances and their actions. This perspective contrasts with the mechanical philosophy and indicates a double irony, as Newton himself maintained a traditional view of substances and their causal actions.

This paragraph focuses on a series of letters exchanged between Newton and Richard Bentley, where Newton addresses the concept of action at a distance, particularly in the context of gravity. Newton argues against the idea that material bodies can act at a distance without the mediation of an immaterial substance. He finds the notion of innate gravity, acting across a vacuum, to be inconceivable and absurd. Instead, he suggests that gravity must be caused by an agent, although he leaves open the question of whether this agent is material or immaterial.

The speaker elaborates on Newton's metaphysical beliefs regarding substance and action, as revealed in his general scholium and his correspondence with Bentley. Newton asserts that God's omnipresent action necessitates God's substantial omnipresence. He also discusses the idea that all action must be attributed to a substance and that a substance cannot act where it is not substantially present. This belief is applied to God, suggesting that God's presence is required for action within infinite space, thus rejecting the Cartesian view of God's non-location.

The paragraph explores Newton's distinction between forces as causes and agents as causes. Newton introduces a technical notion of distance that is sensitive to the presence of a medium between interacting bodies. He argues that gravity, as a force, can act across a vacuum, but if a non-massive medium were discovered that transfers action between bodies, it would indicate no action at a distance between the bodies themselves. This distinction allows Newton to maintain his metaphysical beliefs about substances acting only where they are present while still describing gravitational forces that act across space.

The speaker concludes by highlighting Newton's revolutionary approach to physics, which insulated the study of natural forces from metaphysical considerations of substances and their actions. Newton's work allowed physics to develop independently of traditional metaphysical beliefs about causation, enabling future scientific advancements that challenged the metaphysical tradition. This insulation is seen as a key development in the evolution of modern physics and its understanding of causation.

The final part of the script consists of a question-and-answer session where the speaker addresses various aspects of Newton's causal theory. Topics discussed include Newton's early writings and his departure from mechanical philosophy, the role of mass in Newton's physics, the distinction between forces and substances in causal interactions, and the implications of Newton's views on the nature of God's action in the universe. The speaker also clarifies the difference between Newton's metaphysical beliefs and his physical theories, emphasizing the separation between the two domains in Newton's work.