The Philosophy Book

THE MEDIEVAL WORLD 79

But what is it

that I am?

A thinking thing.

René Descartes

for abandoning the central Islamic
tenet of the resurrection of the dead.
But in the same century Avicenna’s
work was also translated into Latin,
and his dualism became popular
among Christian philosophers and
theologians. They liked the way his
interpretations of Aristotle’s texts
made them easily compatible with
the idea of an immortal soul.

The indubitable self
Some 200 years later, in the 1250s,
Thomas Aquinas championed a
more faithful interpretation of
Aristotle, in which the mind and
body are much more closely tied
together, and his views were widely
accepted by the theologians of the
16th and 17th centuries. But in 1640
Descartes returned to a dualism
that was nearer to Plato’s than
Aristotle’s, and his argument for
it was very like Avicenna’s.
Descartes imagines that there
is a demon who is trying to deceive
him about everything on which he
might possibly be deceived. The one

thing that he cannot be deceived

about, he realizes, is that he exists.

This self is exactly the self which

Avicenna’s Flying Man is sure of,

when he has no other knowledge.

Like Avicenna, Descartes can then

conclude that the “I”, or self, is

completely distinct from the body,

and that it must be immortal.

The ghost in the machine

One very strong objection to the

dualism of Avicenna or Descartes

is the argument used by Aquinas.

He says that the self which thinks

is the same as the self which feels

sensations in the body. For instance,

I do not just observe that there is

a pain in my leg, in the way that a

sailor might notice a hole in his ship.

The pain belongs to me as much as

my thoughts about philosophy, or

what I might have for lunch.

Most contemporary philosophers

reject mind-body dualism, largely

because of the increasing scientific

knowledge of the brain. Avicenna

and Descartes were both very

interested in physiology and they

produced scientific accounts of

activities such as movement and

sensation. But the process of

rational thinking was inexplicable

with the scientific tools of their

Philip Pullman’s tale, Northern Lights,
picks up on the ancient Greek idea of a
person’s soul, or daimon, being separate
to the body, by presenting it as an
entirely separate animal, such as a cat.

times. We are now able to explain

quite precisely how thinking goes

on in different areas of the brain—

though whether this means that we

can explain thinking without

reference to a self is not so clear.

An influential 20th-century British

philosopher, Gilbert Ryle, caricatured

the dualists’ self as “a ghost in the

machine”, and tried to show that

we can explain how human beings

perceive and function within the

world without resorting to this

“ghost” of a self.

Today philosophers are divided

between a small number of dualists,

a larger number of thinkers who say

that the mind is simply a brain, and

the majority, who agree that thinking

is the result of the physical activity

of the brain, but still insist there is

a distinction between the physical

states of the brain (the gray matter,

the neurons, and so on), and the

thinking which derives from them.

Many philosophers, especially

continental European thinkers, still

accept the results of Avicenna’s

thought experiment in one central

way. It shows, they say, that we each

have a self with a first-person view

of the world (the “I”) that cannot be

accommodated by the objective

view of scientific theories. ■