Chapter
One
What’s the problem?
CONSCIOUSNESS IN PHILOSOPHY
Philosophers over the millennia have struggled with versions of the problem
of consciousness. Their solutions can be roughly divided into monist theories –
which assert that there is only one kind of stuff in the world – and dualist theories,
which propose two kinds of stuff.
For most people, dualism is the starting point. Many of our most natural ways of
talking about ourselves, from ‘I need to get a grip on myself ’ to ‘I nearly jumped
out of my skin’, make dualism the default position. Ordinary language makes it
hard to avoid separating a mysterious myself off from ‘my body’ and even from ‘my
mind’: after all, if they are mine, then I cannot be them.
The best-known version of dualism is that of the seventeenth-century French
philosopher René Descartes, and is therefore called Cartesian dualism. Descartes
wanted to base his philosophy only on firm foundations that were beyond doubt.
If he had been holding your pencil, he might have made himself imagine that it
did not exist and that his senses were deceiving him, or that he was only dreaming,
or even that an evil demon was systematically trying to fool him. But, he argued,
in a famous passage in Discourse on Method (1637/1649), even if we doubt every-
thing, there is still something that remains. The fact that he, Descartes, was think-
ing about this was proof that he, the thinker, existed. In this way he came to his
famous dictum ‘je pense, donc je suis’, ‘I think, therefore I am’, and he called it ‘the
first principle of the Philosophy I sought’ (pp. 51–52). In his later Meditations on
First Philosophy (or just Meditations, 1641), Descartes concluded that this thinking
self was not material, like the physical body that moves about mechanically and
takes up space. In his view, the world consists of two different kinds of stuff: the
extended stuff of which physical bodies are made, and the unextended, thinking
stuff of which minds are made.
Descartes’s theory is a form of substance dualism. It can be contrasted with prop-
erty dualism or dual aspect theory (which are sometimes considered to be forms
of ‘anomalous monism’). According to property dualism, the world is composed
only of one kind of substance (the physical kind), but can be described using
mental terms or physical terms, even though one description cannot be reduced
to the other. So, for example, if you are in pain, this fact can be described in mental
terms, such as how it feels to you, or in physical terms, such as which sorts of
neurons are firing where in your nervous system. This theory avoids the need for
two different substances, but leaves open many questions about the relationship
between the physical and mental properties, and therefore comes in many differ-
ent versions.
The insuperable problem for substance dualism is how the mind interacts with
the body when the two are made of different substances. For the whole theory
to work, the interaction has to be in both directions. Physical events in the world
and the brain must somehow give rise to experiences of that world – to thoughts,
images, decisions, longings, and all the other contents of our mental life. In the
other direction, thoughts and feelings must be able to influence the physical
stuff. How could either of these work? Descartes supposed that the two interact
through the pineal gland in the centre of the brain, but proposing a place where it
happens does not solve the mystery. If thoughts can affect brain cells, then either