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Dec 1 Mechanical Philosophy continued: what kinds of theories? • Speculative accounts of hypothetical corpuscles that might cause phenomena. • How to invent these theories, how to choose the most plausible, how to sound convincing? • By analogies with familiar mechanical devices and effects. – Understand the hidden substratum based on everyday experiences, intuition, illustrations. Vortex: Cartesian theory of solar system • Planets are pushed in their orbits as if in a huge whirlpool = vortex theory. • Plenum = universe is full of matter (void is impossible), and particles impact each other in closed circles. Magnetic attraction = caused by corkscrew particles Light is a secondary quality (subjective sensation, not real) • Light is sensed as a pressure against the eye transmitted by particles of the medium. – Everyday analogy as evidence: press against your eyelid & see light. • Color is the perceived effect of the motion of particles, spinning slower or faster. • Descartes’ theory of vision involves mechanical pressure transmitted to back of eye and to brain, causing the figure to be “traced.” Anything goes? • Ad hoc tendencies make the MP easy to apply to any specific phenomenon & thus very popular. – “Posit the existence of sub-microscopic particles of whatever particular shape or size wanted for the purpose.” • How can such a science be verified or refuted? • Acids burn because they are composed of sharp pointy corpuscles that scrape. To a mechanical philosopher, this is preferable to Aristotle saying that acids have an “acidic quality.” • Opium causes sleepiness not because of its “soporific quality,” but because of how its particles affect the brain. • Keen to explain natural magic without using sympathies, correspondences – Laying on of hands – Weapon salve Descartes’ mind-body dualism • He rejected authority of ancients, texts, sense experience. Yet still defended Church authority & doctrines, made his science fit. – Immortal soul & God-given mind & free will • Animals are mere automata (self-acting machines with biological functions). • But humans are unique in having both mechanical body AND immaterial soul (res cogitans = thinking stuff). Automaton (duck) as model for biological processes: only material parts & motions (Borelli first work based on this comparison) Pineal gland (?) • Soul/mind has a special location in the brain = pineal gland. • Unpublished Treatise on Man, gave hypothetical corpuscular accounts of many physiological processes. • “We see clocks, artificial fountains, mills, and other such machines which, altho only man-made, have the power to move on their own accord. But I am supposing this machine [human body] to be made by the hands of God, and so capable of a greater variety of movements and exhibiting more artistry…” Mechanical reflex action vs. vitalism • Replaces Galen’s “vital faculties” & teleology. • “Spirits” = subtle particles that flow thru tubes (blood vessels, nerves, valves, pores) & cause functions of organs, muscles. Science leads to religious heresies? • Ancient atomism (Epicurus, 300BCE) Materialist soul & gods – No design or purpose – • Revived by mechanical philosophers 1630s Pierre Gassendi, Catholic priest – Accepts atoms & void, but rejects atheistic aspects. – • Concerns that Aristotelian science can be materialistic, and magic can be pantheistic (nature = god). Religious implications of MP • Clockwork universe that runs by material parts and motions ONLY. Self-operating. – Any need for God in this system? – Any place for miracles or providence? • Deism = Creator as absentee landlord • Materialism = no immaterial, supernatural explanations Divine will in a mechanical universe (?) • Descartes insists YES French Catholic – Moves to Holland in fear of the Inquisition; always paranoid to publish, esp. on cosmology. – Writes about an “imaginary mechanist cosmos.” – • Keeps God in his physics Creator (first cause) of the laws and motion. – “Conserves” motion of the universe every moment. – Robert Hooke (1635-1703) • Experiments & instruments for Royal Society of London. • 1665 Microscope & first views of the hidden substructures of objects. • Evidence for MP = looks different than ordinary experiences, surface appearances. 1665 Micrographia: empirical evidence of divine design at all levels of nature Robert Boyle (1627-91) • British experimentalist mechanical philosopher (Boyle’s law of gases). • Concerned about deistic tendencies of MP, threat to Christian faith. • World is such a complex, orderly, purposeful clockwork, that it MUST be DESIGNED & TENDED by a wise & caring God (natural theology = handmaiden still). Isaac Newton (1642-1727) • Theology a lifelong obsession (secret heretic, interprets biblical prophecies). • Also made room for ongoing activity of God in his laws of physics – Creator of precise orbits, etc. – Periodically restores the matter & motion of the solar system via comets. – No known cause of gravity, so…