Descartes View of Nature

1
Descartes View of Nature
2
What is Nature?

• Mechanical nature is above all else, a machine,
  like a clock there are no occult or mysterious
  forces at work
• All natural phenomena are mechanical and
  material
• Hence Descartes cannot accept a theory such as
  Newtons gravity
• What is materialism? Doctrine of atomic
  structure of matter dating from the ancient Greek
  Democritus, elaborated by the Roman Lucretius in
  De rerum natura

3
Context of Descartes physiology

• From Aristotle (4th cent. BCE) onward, the heart
  was seen as the principal organ (why not the
  brain instead?)
• Harveys Anatomical Exercises on the Motion of
  the Heart and Blood (1628) posits circulation of
  the blood
• In opposition to earlier theories of the body in
  which specific organs were linked to different
  parts of what was later understood to be a
  circulation system Liver-veins Heart-arteries
  Brain-nerves

4
Why is Descartes physiology important?

• Rejected the so-called faculties of the body
  (from medieval medicine)
• Vegetative - liver
• Vital heart
• Animal (anima soul, Gr.)- brain
• Dissociated the heart from the soul
• Denied connection b/w the heart and the sun.
• Accepted Harveys circulation of the blooda
  radical new view of the body
• But denied Harveys theory of the motion of the
  heart.

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Descartes mechanical heart

• Descartes offered a purely mechanical explanation
  of the heat of the heart
• this movement that I have been explaining
  followsfrom the mere disposition of the organs
  that can be seen in the heart by the naked eye,
  and from the heat that can be felt with the
  fingersas does movement of a clock from the
  force, placement, and shape of its counterweights
  and its wheels (p. 28, middle see also p. 26,
  top).

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Descartes theory of circulation

• Heart is hot by analogy to spontaneous generation
  in hay-mows (what is that? Think compost!)
• Heart vaporizes venous blood as it enters the
  heart
• Expansion occurs, propelling blood into the
  arteries
• But Harvey had already shown that the heart
  contracts, not expands (see Losee, p. 81).

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Descartes Animal-Machine

• On the mechanical model, Descartes posits the
  Animal-Machine human body also a machine.
• 3 kinds of soul (traditional) vegetative,
  animal, rational (p. 33 animal has a kind of
  soul)
• ONLY the human soul is rational and expressly
  created (has logos) animals have non-rational,
  animal souls how do we know this?
• Morris argues that in Descartes view, animals
  could feel but not think animals can be
  sentient because sentience is mechanically
  explainable (Bêtes-machines, 2000, p. 401, 402).

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Animals

• What are the differences between human and
  animal?
• How does Descartes demonstrate the difference
  between human and animal?
• Why is he so concerned with this difference?
• What are some of the key passages?

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Peter Singer on Descartes

• Descartes theory allowed the experimenter to
  dismiss any qualms he might feel Descartes
  himself dissected living animals in order to
  advance his knowledge of anatomy, and many of the
  leading physiologists of the period declared
  themselves Cartesians and mechanists (Animal
  Liberation 1975 , p. 131)
• Singer follows this with a grisly quote from an
  experimenter of the seventeenth century.
• Good material here for essays!

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Pt. 6 Descartes practical programme

• -Conquest of nature we should make ourselves
  masters and possessors of nature
• -Medicine and the human bodychief areas to be
  investigated
• -Many experiments to further medical and other
  scientific work, but too many for Descartes to
  perform on his own
• -Therefore, science must be organized,
  researchers must engage in cooperative
  experimental endeavor and communicate
  experimental results.

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Descartes programme, cont.

• I see quite well what approach one must take
  in order to make most of the experiments but I
  also see that they are of such a kind and of so
  great a number that neither my adroitness nor my
  financial resourceswould suffice for all of
  themI would oblige all those who desire the
  general well-being of mento communicate those
  experiments that they have already performed and
  to assist me in the search for those that remain
  to be performed (emph. added p. 37).