Think: A Compelling Introduction to Philosophy (9 page)

Why do philosophers talk so much about bizarre possibilities that other people happily ignore (one of the things that gives the
subject a forbidding look and a had name)? The reason is that the
possibilities are used to test a conception of how things are. Here
they are being used to test the conception of mind and matter that
gives rise to them. The argument is that if mind and matter are
thought of in the Cartesian way, then there would be wide-open
possibilities of a bizarre kind, about which we could know nothing. So, since this is intolerable, we should rethink the conception
of how things are (this is called the metaphysics). A better conception of mind and its place in nature should foreclose these possibilities. The aim is not to wallow in scepticism, but to draw hack
from any philosophy that opens up the sceptical possibilities. We
would say: according to Cartesian dualism the Zombie possibility
and the Mutant possibility are both wide open. But that just shows
there is something wrong about Cartesian dualism. The mental
and the physical just aren't as distinct as it is claiming. Because it really is not possible that (say) someone who has just stubbed their
toe and is howling with pain is doing so because they are in a mental state like that which I get into by hearing middle C on a clarinet.
That mental state just cannot he expressed by howling or groaning.
The tie between the intrinsic nature of the mental state-what it
feels like-and its expression is closer than that. We know that
someone who has just stubbed their toe is not howling because
they have an experience just like the one I have when I hear middle
C on a clarinet. We know that they are experiencing something
very like what I experience when I stub my toe.

The argument from analogy to other minds was the particular
target of Wittgenstein. Wittgenstein's main objection to the `argu ment from analogy' is not simply that it is so weak. He tries to show
that if you learned about mental events entirely from your own
case, it would not be possible for you even to think in terms of
other people's consciousness at all. It would be as if, were Ito drop
a brick on your toe, there is simply no pain about-I feel noneand that is the end of it. But since we do think in terms of other
minds and their experiences, we have to conceptualize them some
other way.

On this account, the way forward is to reject the picture of mind
and body given to us by Cartesian dualism. And we should be encouraged to reject Cartesian dualism by metaphysical as well as
epistemological pressures. Can we really get a possible picture of
how the world is from Cartesian dualism, never mind about
whether we know it is like that? Consider the Zombie again. His
physical functioning is identical with ours. He responds to the
world in the same way. His projects succeed or fail in the same way:
his health depends on the same variables as ours. He may laugh at
the right places, and weep at appropriate tragedies. He may be
good fun to be with. So what is the lack of consciousness doing? Or,
putting it the other way round, what is consciousness supposedly
doing for us? Are we to conclude that in us, non-Zombies, mental
events exist but do not do anything? Is consciousness like the whistle on the engine: no part of the machinery that makes things happen? (This is the doctrine known as epiphenomenalism.) But if
minds do not do anything, why did they evolve? Why did nature go
in for them? And if mental states really don't do anything, how do
they enter memory, for example?

This is the problem of brain-mind interaction, as it presents itself to Cartesian dualism.

The issue here is beautifully summed up in a debate between John
Locke and his contemporary, the great mathematician and philosopher Gottfried Wilhelm Leibniz (1646-1716). Locke was
another seventeenth-century thinker who worried about the implications of the modern scientific view of the world. In particular,
he worried about the point of causation, at which the motions of
particles in the brain give rise to ideas, such as those of colour, in
the mind. In the following passage he is talking of the way in which
bombardments of small atomic particles give rise to things like
smells, tastes, sounds, and colours:

Let us suppose at present, that the different motions and figures, bulk, and number of such particles, affecting the several
organs of our senses, produce in us those different sensations,
which we have from the colours and smells of bodies, v.g. that
a violet, by the impulse of such insensible particles of matterof
peculiar figures, and bulks, and in different degrees and modifications of their motions, causes the ideas of the blue colour,
and sweet scent of that flower to be produced in our minds. It
being no more impossible, to conceive, that God should annex
such ideas to such motions, with which they have no similitude; than that he should annex the idea of pain to the motion of a piece of steel dividing our flesh, with which that idea bath
no resemblance.

Locke shared the view we have already met in Newton and
Descartes, that some causal processes were relatively intelligible,
notably those in which one quality, like motion, is passed on from
one particle to another by impact. But the moment of body-tomind causation, in which motions in the brain produce something
entirely different, the sensations of smell or colour, or pain, was entirely obscure. It is just an amazing fact that the mental events
occur when they do. It is due to what Locke elsewhere calls the'ar-
bitrary will and good pleasure' of God, `the wise architect' who 'annexes' particular modifications of consciousness to particular
physical events. In Descartes's terms, Locke thinks we have no `clear
and distinct' idea of just what kinds of system God might choose as
suitable places for him to superadd consciousness. It would just be
a brute fact that the universe is organized so that some kinds of system do, and others do not, possess consciousness at all. And it is
just a brute fact that their consciousnesses change and acquire definite properties at the time that their physical selves change and acquire particular properties. The contrast is between a rational and
intelligible connection, such as we find in the a priori discipline of
mathematics, and the fact that certain `motions' just do produce
the sensations in us that they do. This is the brute fact, the consequence of God's good pleasure.

Actually Locke is not so far here from the doctrine known as occasionalism, which was embraced by another contemporary,
Nicolas Malebranche (1638-1715). According to this, physical events do not strictly cause or bring about mental events at all.
Rather, they provide the occasions upon which God himself inserts mental events of appropriate kinds into our biographies.
Strictly speaking, our bodies do not affect our minds, but only provide occasions on which God does. Locke himself does not say this,
but we might reflect that there is precious little difference between,
oil the one hand, God intervening at his good pleasure to make it
that the dividingof the flesh by the steel brings about a sensation of
pain, and, on the other hand, God directly injecting a sensation of
pain into the soul whenever there is a dividing of flesh by the steel.

Locke's doctrine deeply upset Leibniz. In the following passage
from his New Essays, which are a blow-by-blow commentary on
Locke, Philalethes is Locke's spokesman, and Theophilus is I.eib-
niz's. Note the direct quotation from the passage from Locke
above:

t>tln.nl.EtItra. Noly, when certain particles strike ourorgarts
in various ways they cause in its certain sensations of colours
or of tastes, or of other secondary qualities which have the
power to produce those sensations. 'it being no more impossible, to conceive, that God should annex such ideas has
that of hcatj to such motions, with which they have mr similitude; than that he should annex the idea of pain to the motion of a piece of steel dividing our with which that idea
hath no resemblance.'

rHEOPHILUS. It must not be thought that ideas such as those
of colour and pain are arbitrary and that between than and
their causes there is no relation or natural connection: it is not
God's way to act in such an unruly and unreasoned f shion. I
would say, rather, that there is a resemblance of a kind-not a perfect one which holds all the way through, but a resemblance in which one thing expresses another through solve orderly relationship between them. Thus an ellipse, and even it
parabola or hyperbola, has some resemblance to the circle of
which it is it projection on it plane, since then there is it certain
precise and natural relationship between what is projected
and the projection which is made front it, with each point on
the one corresponding through a certain relation with it point
on the other. This is something which the Cartesians have
overlooked; and on this occasion, sir, you have deferred to
them more than is your wont and more than you had grounds
for doing.... It is true that pain does not resemble the movement of a pin; but it might thoroughly resemble the motions
which the pin causes in our body, and might represent them in
the soul; and 1 have not the least doubt that it does.

Where Locke sees only `God's good pleasure, Leibniz seems to be
insisting there must he a rational connection. The events in the
soul must bear some quasi-mathematical relationship to the 'motions' in the brain and body that bring them about.

We can put the issue like this. Imagine God creating the universe. How much does he have to do? One attractive doctrine
would be this: he has to create the physical stuff and the laws of
physics, and then everything else follows. On this view, by fixing
the physical state of the universe at all times, a creating God fixes
everything at all times. If he had wanted to make a world in which
something was different-say, one in which pinpricks were not
painful-then he would have to have tinkered with the physical
facts so that this did not come about. He would have had to fix up
different nerves and pathways in the body and brain. There is no independent variation whereby the physical could stay the same,
but the mental be different. This is Leibniz's position, at least as it
appears in this passage. (A different interpretation of Leibniz has
him thinking that there is independent variation but God has, of
course, chosen the best way of associating mental and physical
events.)

Locke, on the other hand, thinks that God has two different
things to do. First, fix all the physics and laws of physics. But second, decide how to `annex' mental events to physical events, fixing
up psycho-physical relations. It is as if the world has two different
biographies, one of its physical happenings and one of its mental
happenings, and God had to decide how to relate them. On this account, there could be independent variation. God could have kept
the physics just the same, but decided not to annex pain to pinpricks.

Consider now a person (yourself) and a physical duplicate of
that person (a twin). If Locke is right, then it is in principle possible
that the twin is a Zombie or a Mutant. Although his or her physical
self is just like yours, it would he an arbitrary exercise of God's
bounty to make their mental life similar as well. This is especially
obvious on the `occasionalist' version of the view: perhaps for his
own inscrutable reasons God treats my stubbing my toe as an occasion on which to insert pain into my mental biography, but not
so for you. On the other hand, if Leibniz is right, there is no such
possibility. If you and your twin both stub your toes with the same
force, and react physically in the same ways, then the`expression'of
the physical events in your minds must also be the same, just as the figures projected by two identical shapes on a plane at an angle
must be the same.

It is interesting that Leibniz uses a mathematical analogy. It is
not just that he was an even better mathematician than Descartes,
and amongst other things invented the calculus. It is rather that for
Leibniz the whole order of nature must eventually be transparent
to reason. When things fall out one way or another it is not just that
they happen to do so. There must be, if we could only see far
enough, a reason why they do. Things have to make sense. When
Leibniz says God does nothing in an arbitrary or unprincipled way
he is not really expressing a piece of theological optimism, so much
as insisting that we ought to be able to see why things are one way
or another. This is his `principle of sufficient reason'. In Descartes's
terms, we ought to be able to achieve a clear and distinct idea of
why things fall out as they do. We should be able to gain insight into
why the way things are is the way they must be. It is this confidence
in what ought to be possible to reason that makes Leibniz, like
Descartes, a 'rationalist'.