2007 PHILOSOTHON
Community of Inquiry - 3
What is the nature of the human mind?
Resource Material
The nature of the mind
by Dr R. Neurath Sydney Grammar School -Philosophy Club
Introduction
If you were asked the question “What is the nature of the mind?” you might say (something like) that it was the same
thing as the brain or that it was part of the brain. Further, you might add that in order to understand the nature of the
mind we need to know more about the workings of the brain. In short, there's no more to the mind than can be found in
the brain. If that is how you would answer the original question, then you are (some form of) a materialist. According to
a materialist theory of the mind (i.e. “materialism”) the mind is something physical and can be fully described and
explained within the terms of physical science.
Materialism in some form or other is probably the most widely accepted theory of mind. Not surprisingly, for otherwise
we would be stuck with a real mystery: What sort of thing is the mind if it's not material? So clearly it would be
convenient if materialism were true. It is, however, not without its problems and I want to outline three well-known ones.
In fact they have become quite famous in philosophy over the last 20 years or so. They are:
1.
“What is it like to be a bat?”
2.
Mary the neuroscientist
3.
Zombies
“What is it like to be a bat?”
The American philosopher Thomas Nagel argued that materialism cannot give an account of consciousness. For
materialism will necessarily leave out the subjective nature of consciousness. Materialism describes the mind in objective
scientific terms such as neurons, neuron firings, neurotransmitters, stimulation of C-fibres, synapses and so on. To
explain what he means by the subjective nature of consciousness Nagel introduces the idea of “what it is to be like
something”, in particular “what it is like to be a bat”. He chooses bats because, though mammals and therefore clearly
conscious, the sensory system of a bat is radically different from ours. Bats are blind but experience the world by
echolocation. This involves emitting high-pitched squeaks which bounce off objects and are then transmitted to the bats'
ears – similar to radar. The point is that whatever bat experience is like, and it is obviously vastly different from ours,
there is something which could be described as a "what it is like to be a bat”. There is a way in which the world appears
to the bat. It is this “what it is like to be” which captures the essentially subjective nature of consciousness. And it is this
essentially subjective aspect of consciousness which materialism can't explain.
Paul Churchland, another American philosopher, has replied on behalf of materialism. He considers proprioception, our
awareness of the position of our limbs – knowing where your right arm is even with eyes closed. This way of knowing is
unique to me. You can't be aware of the position of my limbs in the way I can. But a unique way of knowing does not
mean that there is anything non-physical about what is known, in this case the position of my limbs. The neural pathways
involved when I know where my right arm is are quite different form your neural pathways when you know where my
right arm is. However, what is known in each case is something perfectly physical, namely the position of my right arm.
Thus, Churchland argues, the “what it is like to be” character of consciousness can be explained in physical terms.

What do you think about this?

Is Churchland's reply satisfactory?

How could Nagel reply to Churchland?
Mary the neuroscientist
This argument was produced by the Australian philosopher Frank Jackson. Mary is a future super neuroscientist who, we
suppose, knows all there is to know about the human brain. However she has a congenital condition which prevents her
perceiving colour – her vision is monochromatic so that for her everything appears like a black and white movie. Mary
knows all there is to know about the neural basis of seeing something red, for example, but can't see red herself. There is
a certain gap in her knowledge. But since, we suppose, her knowledge of brain mechanisms – all the material facts – is
complete, the material facts are not all there is to conscious experience. Mary knows all the material facts but has no
conscious experience so conscious experience is something in addition to facts about brain mechanisms. Thus, since even
a complete neuroscience leaves out the facts of conscious experience, there must be something non-physical about
conscious experience. In other words, materialism is false.
Churchland has replied to this argument in a way similar to the reply to Nagel. There are two ways of knowing about
colour, by direct perception and by neuroscience. Mary lacks the ability to directly perceive colour but has a perfect
apprehension of colour via neuroscience. However, Churchland argues, this doesn't mean that there is any difference in
what is known in either case. Even if the way of knowing is different the object of knowledge may be the same. There is
no reason, therefore, why the object of our direct perception can't also be physical, as is the object of our knowledge via
neuroscience. Materialism survives.

Do you think that Churchland's reply succeeds?

Why?

Why not?
Zombies
The problem of zombies has been raised by the Australian philosopher David Chalmers. By a “zombie” Chalmers means
someone who has no conscious experience at all. Your zombie twin could be exactly like you, molecule for molecule, but
would have no conscious experience. Thus if you and your zombie twin were at the dentist having a tooth extracted
(without anaesthetic), then you would experience excruciating pain whereas your zombie twin would feel no pain or
anything at all.
The zombie argument against materialism can be expressed as follows:
1.
I have conscious experiences.
2.
It is logically possible that there is an exact physical replica of me (molecule by molecule) – my zombie twin who has no conscious experiences.
3.
If my zombie twin is physically identical with me but has no conscious experiences, then facts about
consciousness are different from and additional to physical facts (about molecules, brains, etc).
4.
If facts about consciousness are additional to physical facts then materialism is false.
To understand the argument you need to know what is meant by “logically possible”. The term “logically possible” means
“not self contradictory” or in other words “logically consistent”. Consider the statement that there is a human being who
has grown to a height of one kilometre. This situation is logically possible because, though contrary to laws of nature, the
statement is not actually contradictory. On the other hand, the notion of an even prime number greater than two is
logically impossible.
To return to the argument, if a zombie twin is logically possible, then facts about consciousness can't be the same as
physical facts because if they were the same it would be (logically) impossible to have one without the other. Compare: If
water is the same as H2O, then it would be impossible to have water without H2O – it would actually be contradictory to
have one without the other. The same applies to facts about consciousness and physical facts.
Thus the key question is: Is the hypothesis of a zombie twin logically possible? Is that hypothesis logically consistent?
The problem, then, is to establish the logical possibility of a zombie twin. Logical possibilities are not always easy to see.
Is it logically possible for an effect to precede its cause? It would seem to be contradictory but at the quantum level there
are certain strange phenomena which physicists describe as effects preceding their causes. Conversely, something may
seem logically possible and yet not be. For example, it may have seemed logically possible to find a solution of Fermat's
equation x^n + y^n = z^n, but we now know that it is not possible i.e. not logically possible. The (perhaps apparent)
logical possibility of a zombie twin may be like that.
References

T. Nagel, What is it Like to be a Bat?

F. Jackson, Epiphenomenal Qualities

D. Chalmers, The Conscious Mind

P. Churchland, The Engine of Reason, the Seat of the Soul