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DESCARTES, RENÉ DU PERRON (b. La Haye,
Touraine, France, 31 March 1596; d. Stockholm,
Sweden, 11 February 1650), natural philosophy, scientific
method, mathematics, optics, mechanics, physiology.
DESCARTES: Physiology.
drew throughout the rest of his intellectual life. In
1637, for example, Descartes published two important
works: Discours de la méthode and Dioptrique. In both
he uses physiological ideas from the unpublished
Traité at important points in his argument. Specifically,
in part V of the Discours, Descartes employs
a summary of his cardiovascular physiology to illustrate
how the newly discovered laws by which God
orders his universe are sufficient to explicate certain
of the most important human functions, and the Dioptrique
includes a summary of his general theory of
sensation as a preliminary to a detailed study of image
formation and visual perception. In the 1640's, too,
Descartes drew heavily upon the unpublished Traité.
The complicated arguments of the Passions de l'âme,
published near the end of that decade, rest firmly on
the extensive survey of basic Cartesian physiology
incorporated in part I, while Descartes's unruffled
assertiveness in his correspondence and later philosophical
writings on the “beast-machine” makes full
sense only against a background provided by the
Traité's automaton.
Descartes, however, had left one major physiological
problem untreated in the Traité: the reproductive
generation of animals and men. He had insisted
for reasons of methodological circumspection
that the homme of the Traité was directly contrived
by God. The Cartesian program, of course, was to
explain all but rational, deliberately willful, or self-conscious
behavior in terms of mere mechanism. He
had eliminated the souls, principles, faculties, and
innate heats of traditional physiology and had systematically
replaced them with hypotheses and analogies
of purely physical nature. But generation had
escaped, and its explanation in mechanistic terms was
clearly needed for the logical completion of his system.
Recently proposed theories of animal generation
had left the subject replete with Galenic faculties and
Aristotelian souls, and even William Harvey was soon
to show himself content with innate principles and
plastic forces as the controlling agents of embryonic
development. Descartes, to be consistent, could not
accept these explanatory devices and had, therefore,
to formulate some alternative.
His correspondence and certain manuscript remains
show that Descartes had actually been deeply concerned
with the problem of animal generation for a
considerable period of time. Earliest references in the
former occur in 1629, and snippets of the latter reveal
fitful grapplings with the problem, some of them even
leading to direct anatomical investigations undertaken,
apparently, as a means for providing clues to
the processes involved. Descartes's ideas on the subject
really seem to have crystallized, however, in the
late 1640's, when he triumphantly announced his
“solution” to the long-plaguing problem in a series
of enthusiastic letters to Princess Elizabeth. The ideas
alluded to in these letters appear to be those published
as the De la formation du foetus, which Descartes
completed not long before his death.
First published by Clerselier in 1664, the Formation
is a curious essay. Unlike the Traité de l'homme, which
much preceded it in date of composition, the Formation
consists mainly of bald assertions and only the
vaguest mechanisms. Generation commences when
the male and female seeds come together and mutually
induce a corpuscular fermentation. The motion
of certain of the fermenting particles forms the heart,
that of others the lungs. Streaming of particles as the
process continues furrows out the blood vessels; later,
membranes and fibers are formed which ultimately
weave together to construct the solid parts. The formation
of the bodily parts is described in these vague
terms (no mechanism of organ or vascular development
is ever made more precise than this), yet
Descartes apparently felt satisfied with his results. For
by describing generation in chemical and corpuscular,
rather than vital or teleological, terms Descartes had,
at least in his own mind, completed the mechanistic
program for physiology. Everything in the animal's
life, from its first formation to its final decay, now had
an automatic, mechanical explanation.
The impact of the Cartesian physiological program,
once it was publicly known, was enormous. In two
ways—philosophically and physiologically—Descartes
transformed long-standing beliefs about animals
and men. Philosophically, of course, his notions of
mind-body dualism and animal automatism had extremely
important implications that were not lost on
Henry More, Malebranche, Spinoza, and Leibniz,
along with many others in the seventeenth century.
The “beast-machine” idea also had continuing ramifications
in the eighteenth century, leading, at least
according to Aram Vartanian, directly to La Mettrie's
L'homme machine. Also, according to Vartanian,
Descartes's posthumously published views on human
function and animal generation exerted important
philosophical influence, contributing greatly to the
eighteenth-century concern with these biological subjects
by many of the philosophes. But physiologically,
too, Descartes's conceptions had an impact that in
many ways was even more impressive than the philosophical
influence, because it affected the actual
course of contemporary science.
Almost as soon as Descartes published his Discours
de la méthode, a few professors of medicine began to
react to specific Cartesian physiological ideas and to
the general Cartesian program. Plempius at Louvain