MATTER AND CONSCIOUSNESS by Paul M. Churchland
This is one of the books on our cognitive foundations course which I
have just read and enjoyed. It is aimed at the undergraduate, and is
humourous and easy to read. Churchland discusses the nature of
conscious intelligence and covers both the dualist and materialist
points of view. He did not, however, answer Stephen's question of why
consciousness is necessary. A question, by the way, which has wound up
everyone I have put it to.
I have made a precis of the main theoretical positions on consciousness
for my own interest, which I decided to share if anyone else is
interested.
1. Dualism: Claims that the nature of conscious intelligence is
non-physical, associated with religious ideas and Descartes. Problem of
how a non physical-substance can interact with matter.
Popular Dualism: A person is a 'ghost in a machine' - mind is in
contact with brain and can exchange energy. But is no evidence for a
thinking substance.
Property Dualism: There is no substance, but brain has a special set
of properties associated with it which are non-physical eg feeling a
pain, sensation of red etc. These cannot be reduced or explained by the
physical sciences as they are purely mental.
Epiphenomenalism: Mental phenomena are side effects of brain
complexity. They are caused by brain activity, but have no causal
effects on brain.. So it is an illusion that our beliefs & desires
determine our actions. ( I think this argument, radical though it may
be, is supported by a study by Nisbett & Wilson, which showed that the
explanations offered for ones own bwhaviour often have little or no
origin in introspection, despite sincere beliefs to that effect, but
are instead spontaneously confabulated on the spot as explanatory
hypotheses to fit the behaviour & circumstances observed. These are
often wrong, since the 'introspective' reports given prove to be a
function of wholly external features of the experimental situation
which were under the control of the experimenters.) A less extreme view
comes under the heading of 'interactionist property dualism. This
asserts that mental properties do have causal effects on the brain.
Mental properties still held to be emergent and irreducible.
Main arguments for dualism:
1. Religious belief, or belief in a soul
2. Introspection - we feel that we have mental states
3. Argument from irreducibility- can we reduce fragrance of a rose to
the physical?
4. Parapsychological phenomena - but not much evidence
Main arguments against dualism:
1. Religious arguments lack empirical evidence 2. False to believe that
introspection reveals things as they really are 3. Many abilities
thought to be mental are duplicated by computers 4. The effect of
chemicals, drugs, lesions etc on the mind suggests that consciousness
is very much affected by physical states. 5. Evolutionary argument that
the human species & all of it's features are the physical outcome of a
physical process. 6. No need to postulate 2 substances - physical and
mental/spiritual, when only physical properties are necessary to
explain phenomena.
2. Philosophical behaviourism: claims that talk of ghostly inner states
like beliefs and desires is a shorthand way of talking about actual &
potential patterns of behaviour. But sensations do have an intrinsic
qualititive nature.
3. Reductive Materialism/Identity Theory: Each type of mental state is
identical with some physical state or process within the brain.
4. Functionalism: Thinks it unlikely that a 1:1 match will be found
between our current psychological terminology and the phsyical
processes revealed by neuroscience. Believe the defining feature of a
mental state is the set of causal relations it bears to 1. enviromental
effects on the body, 2. other types of mental states, 3. bodily
behaviour.
5. Eliminative materialism: Believe our current psychological framework
is a misleading conception of the causes of human behaviour and will be
overthrown when a more accurate framework emerges from the
neurosciences ( I can see, for example, 'black box' terminology being
overthrown by connectionist, or neural network models). This view
challenges entrenched assumptions about our view of mental states such
as desire, fear, purpose etc.
That covers the main approaches and theories. The rest of the book
discusses the problem of other minds, i.e. how can we know we
experience the same things. Churchland also talks about self
consciousness, and the likely contributions of future research in
artificial intelligence and neuroscience to the debate.
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