Descartes is most
famous today for two developments - Cartesian coordinates, which
still play a key role in mathematics, and dualism, a philosophy
which proposes a sharp distinction between body and soul, matter
and spirit. According to Cartesian dualism, the spirit is personal
and nebulous, and matter must therefore be impersonal and
concrete.
In Descartes's image
of the universe, matter is immersed in an unseen, immeasurable
medium called the ether. God endowed the universe with movement at
the beginning of time and allows it to run spontaneously but in
accordance with his will. Because in this scheme matter fills all
of space, there can be no such phenomenon as a vacuum and all
motion is produced by matter impressing on other matter within the
medium of the ether. Descartes expressed this in his famous theory
of vortices, in which he pictured movement, such as the fall of a
stone to the earth, as being like the movement of a feather or a
straw caught in an eddy or a whirlpool.
Descartes rejected
mysticism and the occult in his writings and visualised the
universe as a machine. Every action involving matter was purely
mechanistic, and matter had no contact with spirit. To Descartes,
all animals - including humans - were also mere machines. Humans
had a spiritual aspect, a soul, but this had no link with our
Physical selves.
These ideas were
highly controversial. On a scientific level, Descartes's concepts
were unverifiable and he did not contrive experiments to support
his theories. On a superficial level, his vortex theory did not
clash with the doctrines of Galileo, in that it did not contradict
experimental evidence. Galileo had shown that, because of inertia,
all movement continued until stopped, and Descartes proposed that
the universe had been set in motion by God. The two ideas were not
incompatible: if we assume the Creator set things in motion they
would continue until stopped by, say, the intervention of
mortals.
But the most radical
aspect of Cartesian philosophy was that it implied to many that,
once the universe had been set in motion, God was no longer needed.
The Creator had been effectively demoted from 'Supreme Good' to
'First Cause'. Naturally this was a view hotly disputed by
theologians and the majority of philosophers, many of whom had been
brought up on Aristotle and still thought along the same
lines.
