Revolution in “ natural philosophy” The success of Newton’s physics had immediate effect on: 1. metaphysics i. concepts of body, force and motion ii. concepts of space and time iii. cosmology iv. theology 2. methodology

Methodology The basic problem of natural philosophy seems to be to discover the forces of nature from the phenomena of motions, and then to demonstrate the other phenomena from these forces. (Newton, Principia Preface 1st ed. 1687) Three-step procedure: 1. isolate certain natural phenomena (phenomena of motions) 2. discover the forces of nature that cause these phenomena 3. demonstrate other natural phenomena from the discovered forces

Methodology Examples of the three-step procedure: ‘1. the phenomenon of motion: bodies falling on earth ‘2. discovering the forces that cause bodies to fall on earth: mass, inertia (body and medium), gravity of the Earth ‘3. demonstrating other phenomena from discovered forces: motion of planets around the Sun, motion of satelites around Jupiter and Saturn, motion of comets, motion of the Moon, of the tides etc. Demonstration: 1. deductive procedure (axioms, corollaries, theorems...) 2. mathematical procedure (quantification, calculation, diagram...)

Methodology “Rules for the study of Natural Philosophy” (from Principia, Book III: The System of the World) Rule 1: No more causes of natural things should be admitted than are both true and sufficient to explain their phenomena. - the principle of economy (Ockham’s razor) Rule 2: Therefore, the causes assigned to natural effects of the same kind must, so far as possible, be the same. - the principle of universality (“e.g. the light of a kitchen fire and the sun”) Rule 3: Those qualities of bodies that cannot be increased or diminished and that belong to all bodies on which experiments can be made, should be taken as qualities of all bodies universally. - the principle of generalization (from the observable to the unobservable)

Methodology “The extension, hardness, impenetrability, mobility, and force of inertia of the whole arise from the extension, hardness, impenetrability, mobility, and force of inertia of each of parts; and hence we conclude that every one of the least parts of all bodies is extended, hardess, impenetrable, mobile, and endowed with a force of inertia.” (Principia, Bk. III, Rule 3, explanation) - corpuscularian theory of matter Rule 4: In experimental philosophy, propositions gathered from phenomena by induction should be considered either exactly or very nearly true notwithstanding any contrary hypotheses, until yet other phenomena make such propositions either more exact or liable to exceptions. - the principle of “guarded induction” + guarding against? (i) closure to new phenomena (ii) “hypotheses”

Methodology “I have not as yet been able to discover the reason for these properties of gravity from phenomena, and I do not feign hypotheses (hypotheses non fingo). For whatever is not deduced from the phenomena must be called a hypothesis; and hypotheses, whether metaphysical or physical, or based on occult qualities, or mechanical, have no place in experimental philosophy. In this philosophy particular propositions are inferred from the phenomena, and afterwards rendered general by induction.” (Newton, Principia, General Scholium in the 2nd ed. 1713)

Methodology Q: What were the “hypotheses” that Newton abhorred? A: postulated entities and claims that were introduced to explain a phenomenon: i. without an independent study of the phenomenon ii. in isolation from other similar phenomena iii. ignoring or dismissing the phenomena that resist explanation in terms of these entities and claims Examples of “hypotheses”?

Hypothesis : Aristotle Bodies are composites of form and matter, with powers following therefrom

Hypothesis: Leibniz The power to produce motion is in the form, and the inertia, or repugnance to motion, is in the matter.

Hypothesis : Descartes The vortex theory of planetary motion

Metaphysics the concept of body separated from the concept of extension the concept of extension associated with the concept of space - space: infinite, unchangeable, impassive, individisible, homogeneous, eternal the concept of existence associated with space and time - bodies exist in space and time - (created) minds exist in space and time + bodies can excite perceptions in minds + minds can move bodies at will - divine mind does not exist in space and time, but has space and time as its “emanative effects” (or properties) + divine mind is everywhere (omnipresence) + divine mind perceives whatever is in space (omniscience) + divine mind can move at will whatever is in space (omnipotence)

Metaphysics The existence of God deduced from: - the existence of absolute space and time - properties of the universe that cannot be explained by mechanical causes (gravity, etc.): + particular distribution of matter in the universe. planets in our system sufficiently far apart. other sun systems sufficienty far apart + active principles that set and keep matter in motion (gravity, magnetism, “electric attraction”, “fermentation”, etc.) + planets moving in concentric orbits on the same plane and in the same direction + diurnal motion of the Earth - the need to reform the systems from time to time?