method of philosophic reflection.”
“That I can understand.”
“But that was only part of it. The new physics had also raised the question of
the nature of matter, and thus what determines the physical processes of nature. More
and more people argued in favor of a mechanistic view of nature. But the more
mechanistic the physical world was seen to be, the more pressing became the question
of the relationship between body and soul. Until the seventeenth century, the soul had
commonly been considered as a sort of ‘breath of life’ that pervaded all living
creatures. The original meaning of the words ‘soul’ and ‘spirit’ is, in fact, ‘breath’ and
‘breathing.’ This is the case for almost all European languages. To Aristotle, the soul
was something that was present everywhere in the organism as its ‘life principle’—
and therefore could not be conceived as separate from the body. So he was able to
speak of a plant soul or an animal soul. Philosophers did not introduce any radical
division of soul and body until the seventeenth century. The reason was that the
motions of all material objects—including the body, animal or human—were
explained as involving mechanical processes. But man’s soul could surely not be part
of this body machinery, could it? What of the soul, then? An explanation was required
not least of how something ‘spiritual’ could start a mechanical process.”
“It’s a strange thought, actually.”
“What is?”
“I decide to lift my arm—and then, well, the arm lifts itself. Or I decide to run
for a bus, and the next second my legs are moving. Or I’m thinking about something
sad, and suddenly I’m crying. So there must be some mysterious connection between
body and consciousness.”
“That was exactly the problem that set Descartes’s thoughts going. Like Plato,
he was convinced that there was a sharp division between ‘spirit’ and ‘matter.’ But as
to how the mind influences the body—or the soul the body—Plato could not provide
an answer.”
“Neither have I, so I am looking forward to hearing what Descartes’s theory
was.”
“Let us follow his own line of reasoning.”
Albert pointed to the book that lay on the table between them.
“In his Discourse on Method, Descartes raises the question of the method the
philosopher must use to solve a philosophical problem. Science already had its new
method...”
“So you said.”
“Descartes maintains that we cannot accept anything as being true unless we
can clearly and distinctly perceive it. To achieve this can require the breaking down of
a compound problem into as many single factors as possible. Then we can take our
point of departure in the simplest idea of all. You could say that every single thought
must be weighed and measured, rather in the way Galileo wanted everything to be
measured and everything immeasurable to be made measurable. Descartes believed
that philosophy should go from the simple to the complex. Only then would it be
possible to construct a new insight. And finally it would be necessary to ensure by
constant enumeration and control that nothing was left out. Then, a philosophical
conclusion would be within reach.”
“It sounds almost like a math test.”
“Yes. Descartes was a mathematician; he is considered the father of analytical
geometry, and he made important contributions to the science of algebra. Descartes
wanted to use the ‘mathematical method’ even for philosophizing. He set out to prove