Lecture 21: Mechanical Philosophy II © Darrin Durant 2004

Mechanical Philosophy II: occult qualities & active principles

Cartesian confidence: all qualities are occult, and strictly mechanical explanations can be found for all of them

“… there are no qualities which are so occult, no affects of sympathy or antipathy so marvelous or so strange, nor any other thing so rare in nature (granted that it is produced by purely material causes destitute of thought and free will), that its reason cannot be given [by the mechanical philosophy]”.

Descartes, Principia philosophiae, Pt. IV, §187

 Cartesian critique of Newtonians: Bernard le Bovier de Fontenelle (Eloge of 1727): What Descartes (rightly!) banished, Newton (wrongly!) brought back:

‘Attraction’ had been “banished from Physicks . . . for ever” by Descartes.”

John Keill (1702)

“Although now-a-days the mechanical philosophy is in great Repute, and in this Age has met with many who cultivate it, yet in most of the writings of the Philosophers, there is scarce anything mechanical to be found besides the Name.”

Why this difference of opinion?

-Continental mechanists objected to Newton’s use of occult qualities

-English mechanists followed Gessendi

Pierre Gassendi (1592-1655): Gassendi rejected the self-moving matter theory of Epicurus, replacing it with the theory that God had endowed matter with an internal principle of motion at the Creation.

Occult = Hidden
/ v.Manifest
- Insensible (can’t be sensed)
- Unintelligible (not understandable) / - Directly perceived

 Occult = effects observable, but causes unknown or not perceived

E.g.: Gold has a ‘cordial quality’, the ‘secret virtue in 7’, magnets have a ‘shrewd quality of allowing a husband to test the fidelity of his wife’, ‘glass is poisonous’, mustard has ‘the power to produce inflammation’, rhubarb has a ‘purgative faculty’, Opium has a ‘dormitive virtue’

 Ambiguity = qualities v. qualitates/qualitas

effects causes

*** Aristotelians and ‘the occult’ ***

Aristotelian psychology

Reason

/

Sense Perception

/

Revelation

Sense Image ‘Form’ enters the mind = ‘sifting’

 The ‘process problem’

 No sifting without a sense object

 The ‘smallness problem’

 All material entities can be seen

 Occult = within realm of experience, but outside realm of sense

 Occultism and the 4-element theory

4 qualitates of sensation, hot, cold, wet, and dry

Many qualities, which made no impact on the senses, could not be accounted for in terms of 4 elements

Subclass of occult qualities (individually posited

qualitates)

*** Mechanical philosophers and ‘the occult’ ***

 Why the sense of superiority over Aristotelians? [see Shapin]

 Modern examples?: aspirin, curly hair

 How do you extend the intellect by showing its limits?

 Descartes = supreme confidence

 Insensible mechanisms v.qualitates

 A distinction between manifest & occult?

E.g.: Magnetism

 Insensible entities exist but cannot be known?

 John Locke (1632-1704), Essay Concerning Human Understanding

 Book IV: “Scientiae of bodies” v. “twilight of probability”

 Walter Charleton (1620-1707): Physiologia Epicura-Gassendi-

Charletonia (1654)

 Occult agencies as intellectual refuge (Hobbes agreed)

E.g.: tuning a violin

 Robert Boyle, the Sceptical Chymist (1661)

All qualities are occult

E.g.: the pin & pain

*** Options for Dealing with Occult Qualities/Qualitates ***

Empiricist answer: denial of effect

Reductive answer: cut out as many qualitates as possible

Fictionalist: tentative deciphering of the book of nature

 E.g. Boyle on a good hypothesis (intelligible, consistent, makes

predictions, simple . . . not ‘true’)

Relationism: object/substance and environment

Occasionalism: Malebranche , demi-Occasionalist Leibniz

(activity is internal)

Supernaturalism: Malebranche (matter cannot move itself of its own powers, all activity in God)

M’s occasionalism + radically supernaturalistic aetiology

Scholastics preferred natural explanation (not devil, demons, god)

*** Did mechanists use occult active principles? ***

 Descartes

 Problems with the “communication by impact” model

 Is God eliminated?

 How does passive matter transfer motion?

 Charleton: “Native tendency” in atoms to move = God exists

 Boyle: corpuscles with an inherent vibratory mode

E.g.: the spring of the air

E.g.: the expansion of air upon the application of heat

 Robert Hooke (1635-1703): inherent vibration of the interplanetary

eather explains light and gravity

 Descartes v. Sir William Petty (1664) on magnetism

 Inert screw-like particles v. atoms as magnets

*** Why did ‘activity’ matter? ***

 In Descartes’ system, was God necessary?

 Newton: God required to provide motion

 Descartes “Occasionalistic” defense

versus

English objection God as ‘unworthy’ Puppet-master?

versus

God as clockmaker Active principles in matter, and the

types of God’s intervention

*** A typology of God’s role ***

 Newton, Boyle, Charleton, Hale, Power

 A supervisory role. Know role by empirical inquiry

 Henry More (1614-1687)

’spirit of nature’ dualism : dead matter v. living spirit

 Leibniz

 God as a perfect clockmaker. Know role by reason

 Newton’s defense of active principles

 Unknown causes, but “I feign no hypotheses”

 English “facts of the matter”

*** The dispute over gravity ***

17th century Theology

Voluntarist

/

Intellectualist

Dominant attribute: God’s will / Dominant attribute: God’s reason
God is omnipotent / Certain eternal truths lead God, via reason, to act in certain ways
What God wills is good / God wills what is good
The world cannot be rationally reconstructed. Contingencies mean discovery via empiricism. / It is possible to think God’s thoughts after him = rational understanding of the world.
Newton /
Leibniz
Gravity exists, even if causes occult / Gravity attracts because it does?
Forces in terms of motions / Motions in terms of forces
Force = causes (they are ‘actions’, they ‘compel’ bodies’, ‘draw aside’ planets)
Force = ‘propensities’ (redescribes the effects) / Force = primitive passive force
Essence of body
Matter = primitive active force
Vis viva = living force (measure of effect a moving body produces)
Bodies transfer motion by impact (inelastic) / Bodies transfer motion by impact (elastic compression & restoration)
Active principles explain transfer / Vis viva explains transfer
Matter can be self-active / World composed of monads (living creatures = body & soul = genuine individual = self-active)
Space as ‘Sensorium of God’ / Space is a relational concept

*** Newton’s Gravity ***

 A “manifest quality whose cause . . . is occult”

 But Query 31, Opticks: not everything has an occult specific quality

 An unexplained gravity brought him ‘close to God’

 Assumes: rectilinear inertia and inverse-square law

E.g.: Moon: path = rectilinear motions (centrifugal) punctuated

by periodic discrete impulses towards (centripetal) central body

 Thus: gravity = a mutual attraction, a body ‘drawn in’

 Mutual attraction disturbs cosmic regularity = God intervenes

E.g.: Comets as ‘God’s messengers’?

 Gravity not an essential property of matter: being a mutual action, it cannot be located within a single particle

Principia (2nd edition, 1713): General Scholium (added as a conlcusion)

 Last paragraph outlines two points:

1. On gravity: “Hypothesis non Fingo” (I feign no hypotheses)

  1. Other natural powers: hypothesizes that much phenomena

(electricity, light, magnetism sensation, animal motion) can be explained by “subtle spirit” confined to “gross bodies”

Opticks (1717, ‘Queries’): aether theory?

 Gravity not reducible to contact-action

 Aether has active properties, extends throughout space, and is

the cause of gravity?

 Newton transfers to aether some of the explanatory

responsibilities previously given to subtle spirit

 By Principia (3rd Edition, 1726)

 Last paragraph of 1713 edition retained

 Newton thus reverted to leaving the cause of gravity unknown,

but using subtle spirit to explain other phenomena

 Query 31, Opticks (1730, 4th edition):

“…to derive two or three general principles of motion from phenomena, and afterwards to tell us how the properties and actions of all corporeal things follow from these manifest principles, would be a very great step in philosophy.”

 E.g. 1: Particular stone (magnet) attracts particular substance (iron)

E.g. 2: ‘Amber effect’ (drawing of little light objects to rubbed amber

or glass)

 Both effects not of sufficient universality to be a cause

 Force of attraction and repulsion between particles of universal

and all-pervading subtle spirit might be universal enough

 Gravity as a universal natural power (Gravity is God)?

*** Descartes & Huygens (1629-1695) on Gravity ***

 Heavy bodies pushed toward centre by action of matter that is further away from the centre than they are (centripetal force)

*** Leibniz’s Gravity & Dynamics ***

 If looking at a substance, what comes before Descartes’ ‘extension’?

Forces or Powers, Kraft (German), la force (French)

 “…a natural force everywhere implanted by the Author of

nature …” (Philosophical Letters and Papers, II, p. 712)

 Leibniz (1646-1716) on gravity (Cf. Specimen Dynamicum (1695), and the Leibniz-Clarke correspondence (1715-16))

 Newton’s gravity = “a chimerical thing, a scholastic occult quality”; a “perpetual miracle”; ridiculed it because it is a theory of gravity “performed without any mechanism” or “by a law of God”

 Leibniz’s problem with Newton: dualism of active forces causing change and passive matter resisting change

 Leibniz’s solution = a monism of force (forces both bring about and resist motion); no dualism of matter and force

 Substances characterized by “primitive forces”, which cause inherent activity

 Gravity = “lines of impulse” tending outward (centrifugal) from an attracting body, through a vortical fluid, bringing about reciprocal tendencies inwards (centripetal) by ‘terrestrial bodies’

 An innate property of a newly activated matter

 Substances characterized by ‘primitive forces’ are the “source of things”

 Laws of nature explained by two kinds of “derivative forces”

A) Active forces generate motion

  1. Living force (vis viva) = force of motion of a body

 Arises from infinite number of infinitesimal impulses of dead force

  1. Dead force (vis mortua) = force that arises in the tendency of a body to achieve its state of motion

B) Derivative passive forces (impenetrability and inertia)

  1. Inertia = resistance to motion (inertia manifests primitive

forces, not an innate property of matter)

 Newton’s God = an “imperfect clockmaker”

 Rejects Cartesian “occasionalism”

*** The Gravity Problem ***

 Unintelligible = ‘beyond understanding’ = a way to slur opponents

 Cartesians and Newtonians Gravity is insensible

 Cartesians: gravity unintelligible (no ‘mechanical’ explanation)

 Newtonians: it is OK if gravity unintelligible

Other criteria: - reliable detection, mathematical description

- avoid speculative, individual hypotheses

- reject the “unlevel wits”

 Leibniz: gravity as innate to the body

 Debating gravity was simultaneously

 A debate about the nature of God

 A debate about the actual, and proper, role of God

 A debate about how to explain the natural world

 A personal, political battle

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