We are now going to look at the most famous representative of the
dualist view, the French philosopher René Descartes. Driven
by his desire to find an absolute certainty on which to base the
search for knowledge, Descartes claimed to have discovered one fact
beyond doubt: that he is a thinking thing. This famous argument
- called the Cogito after the Latin phrase, “cogito ergo sum”
(I think, therefore I am) – tries to establish the mind as
a separate substance from the body.
For Descartes, certainty is best supplied by reason. The further
the mind is taken away from its proper objects – logic and
pure reason – the more likely it is to fall into error. Thus,
for Descartes, the purpose of philosophy is to direct the mind away
from the confusing images of the senses towards the indubitable
truths contained within the mind itself.
This project led Descartes to conclude that the mind was a completely
distinct substance from matter. Matter is easily described: it is
measurable, has dimensions, can be touched and seen, sometimes smelt
and tasted, divided, destroyed and altered. Mind, however, can almost
be defined as the opposite of this – in fact, one of the difficulties
with Descartes’ definition is that mind seems to have almost
no positive qualities. It is invisible, without dimensions, immaterial,
unchanging, indivisible and without limit.