Think: A Compelling Introduction to Philosophy (34 page)

This did not strike Descartes and many of his successors as too had.
Descartes himself, as we have seen, still had `reason' to inform him
about the properties objects really had. He did not mind the illusory aspects of the world of appearance-the fact that colours are,
as it were, due to us, and not to the things we see. His position
in this was canonized in English-speaking philosophy by John
Locke.

Locke is very explicit. There are

original or primary qualities of body, which I think we may
observe to produce simple ideas in us, viz. solidity, extension,
figure, motion or rest, and number.

There are also

such qualities, which in truth are nothing in the objects themselves, but powers to produce various sensations in us by their primary qualities, i.e. by the hulk, figure, texture, and motion
of their insensible parts, as colours, sounds, tastes, etc. These I
call secondary qualities.

In this picture there is the scientific world, of objects as they really
are in Locke's time, a world of little particles clinging together to
form bigger bodies, each having the primary, scientific, properties.
This is the scientific picture. There is also the manifest image: the
coloured, smelly, tasty, noisy, warm, or cold world we think of ourselves as inhabiting. But the manifest image is either in or at least
largely due to the mind. The scientific world is not.

Are objects then not really coloured or smelly in Locke's view?
There is a sense in which they are: objects have the powers to produce colours and smells in us. Nevertheless, these powers are not
the colours and smells themselves.

What I have said concerning colours and smells may be
understood also of tastes and sounds, and other the like sensible qualities; which, whatever reality we, by mistake, attribute to them, are in truth nothing in the objects themselves,
but powers to produce various sensations in us, and depend
on those primary qualities, viz. bulk, figure, texture, and motion of parts; as I have said.

The various sensations in us do not in any way resemble the powers that give rise to them.

Locke's view is often thought of as a natural, common-sense,
scientific realism. We may substitute energies, forces and fields, or
sub-atomic particles for his little particles of matter of peculiar figures and bulks. However, the essential opposition between the world of science and the manifest image remains in many people's
minds substantially as he presented it.

Well, is there any problem with that?

BERKELEY'S PROBLEMS

A number of writers in France had difficulties with Descartes's
world-view. In particular, if God was, after all, a kind of deceiver
(although, of course, for our own good) with respect to secondary
qualities, might he also be one with respect to primary qualities? If
it is good of him to make us see in terms of colours, although seen
colours bear no resemblance to anything in physical reality, might
it not be good for him to make us see in terms of objects extended
in space, although physical reality is not actually spatial? Colours
are here a kind of Trojan horse working to reintroduce the general
Evil Demon scepticism that Descartes thought he had beaten
down.

This is an epistemological problem. However, we can become
even uneasier if we think about the metaphysics of the scientific
world. Try to think about what actually fills space. Descartes had
banished all qualities from physical reality except one, extension.
But everyone thought that this was untenable. `Extension' is entirely abstract. A cubic foot of space is one thing; a cubic foot of
space with a body in it quite a different thing. We must conceive of
physical reality in terms of things occupying space, not just space
itself.

Well, we may think, that is fine. Locke has things with properties like `solidity' and `motion. Motion however will not help unless we
have things moving. So let us concentrate upon things. Now a volume of space with a thing in it is known by the solidity or resistance
the thing offers.That is the difference between a cubic foot of space
filled with granite, and a cubic foot of vacuum. So, what is solidity?
Locke is very keen on it:

The idea of solidity we receive by our touch: And it arises Jront
the resistance which we find in body, to the entrance of any
other body into the place it possesses, till it has left it. There is
no idea, which we receive more constantly Iron, sensation,
than solidity. Whether we move, or rest, in what posture soever we are, we always feel some thing under us that supports
us, and hinders our further sinking downwards; and the bodies which we daily handle make us perceive, that, whilst they
remain between them, they do by an ins,rnountable force,
hinder the approach of the parts of our hands that press them.
That which thus hinders the approach of two bodies, when
t/icyare moved one towards another, I call solidity... (1/f any
one think it better to call it impenetrability, he has my consent. Only l have thought the tern, solidity the pore proper to
express this idea, not only because of its vulgar use in that
sense; but also because it carries some thing more of positive in
it than impenetrability, which is ncdative, and is, perhaps,
more a consequence of solidity, than solidity itself. This, of all
Other, seems the idea most intimately connected with and essential to body, so as no-where else to be Jinnl or imagined,
but only in matter.

The solidity of objects seems to come down to their `powers' to exclude other objects from the hit of space they occupy. But can we
rest content with a conception of the world in which there are only different regions of space with different powers? Do we not also
need something, some substance, to possess the powers?

At least Locke allows that we know about solidity, so perhaps its
epistemology is in order. It seems clear that we know about solidity
by what we feel. Locke actually emphasizes this:

If any one asks me, what this solidity is, I send him to his
senses to inform him: Let him put a flint or a foot-ball between his hands, and then endeavour to join them, and he
will know. If he thinks this not a sufficient explication of solidity, what it is, and wherein it consists; I promise to tell him
what it is, and wherein it consists, when he tells me what
thinking is, or wherein it consists; or explains to me what extension or motion is, which perhaps seems much easier.

Although Locke was not particularly sensitive to it, the problem
with this was grumbling in his time, and it erupted at the beginning of the eighteenth century in the writings of Pierre Bayle
(1647-17o6) in France and the Irish philosopher George Berkeley
(1685-1753). Berkeley makes a number of devastating objections to
the Cartesian/Lockean world-view. His position is that it does not
hold together either metaphysically, or epistemologically. His case
is complex and many-layered, but we can appreciate its general
strengths under two headings.

(1) Look again at Locke's view of how we know about solidity. If
this is all we can say, in that case how is solidity not on all fours with
colour, or felt heat, or smell? If those sensations give us no real idea
of the qualities of real things, being just excited in us by the 'powers' of real things, how is it any better with solidity? How can you get from the sensations of solidity in the mind, to any resembling
property in the world? Whatever solidity is'in the hind' it is not
the same as solidity in the world. Our ideas are not solid, so what is
the sense in saying that they 'resemble' solid things?

And if solidity disappears from the real world, what is left?
Berkeley's own answer to this is notorious: nothing. His world retreats entirely into the mind-the doctrine known as subjective
idealism.

(2) The Lockean view seems to require at least that we conceive of
a world in purely primary-quality terms, bleaching out everything
that according to him resides in the mind. But can we? Berkeley
says,'l deny that I can abstract one from another, or conceive separately, those qualities which it is impossible should exist so sepa-
rated.'Thinkof an ordinary physical object,say,a tomato.'Abstract
out, its colour, feel, smell, taste, and the sensations you get as you
play your hands round it. What is left? An invisible, intangible, undetectable tomato-surely no better than no tomato at all! Hume
puts this objection superbly (in the following quotation,'the modern philosophy' is Locke's position):

The idea of solidity is that of two objects, which, being impelled by the utmost force, cannot penetrate each other, but
still maintain a separate and distinct existence. Solidity
therefore is perfectly incomprehensible alone, and without the
conception of some bodies which are solid, and maintain this
separate and distinct existence. Now, what idea have we of
these bodies? The ideas of colours, sounds, and other secondary qualities, are excluded. The idea of motion depends on that of extension, and the idea of extension on that of solidity. It is impossible, therefore, that the idea of solidity can depend on either of them. For that would be to run in a circle,
and make one idea depend on another, while, at the same
time, the latter depends on the former. Our modern philosophy, therefore, leaves us no just nor satisfactory idea of
solidity, nor consequently of matter.

Or in other words: `[A]fter the exclusion of colour, sounds, heat,
and cold, from the rank of external existences, there remains nothing which can afford us a just and consistent idea of body.' Berkeley
and Hume deny that we can really understand the alleged properties of the alleged independent world, except in terms drawn from
our own experience-our own minds. The `modern philosophy'
or scientific world view requires us to make sense of a `scientific' or
`absolute' conception of reality, thought of in terms of spaceoccupying things, independent of us, whose arrangements explain
all that can be explained about the entire universe, including us
and our experiences. But if this conception is flawed at its heart, we
have to look elsewhere.

FORCES, FIELDS, AND THINGS

In the quoted passage Hume asked what conception we had left
of the `bodies' that are impenetrable to each other, and argued
that without the `stuffing' afforded by the secondary qualities,
there was no answer. But this raises a more general problem: what conception do we ever have of bodies, apart from their powers of
interaction with each other, and with us?

This is not the place to enter into details of physical thinking, but
we can take up the story in the words of one of the greatest of physicists, Michael Faraday (1791-1867). Suppose we try to distinguish a
physical particle a from the powers or forces in whereby it makes its
influence known, then, Faraday writes:

/Tlo my mind... thea or nucleus vanishes, and the substance
consists of the powers, or m, and indeed what notion can we
form of the nucleus independent of its powers: what thought
remains on which to hang the imagination of an a independent of the acknowledged forces? Why then assume the existence of that of which we are ignorant, which we cannot
conceive, and for which there is no philosophical necessity?

Hume's protest about bodies apart from solidity is here taken on
the chin, as it were. We just do not have to think in terms of things
apart from their powers.

In that case the world of physics, the `scientific image, resolves
itself into a vast flux of forces: presumably such things as gravitational forces, electromagnetic attractions and repulsions, or if we
turn up the magnification, strong and weak interactions amongst
elementary particles. But then there is something very uncomfortable going on. For remember that the argument is entirely general,
so that these `particles' themselves resolve into other `forces'. This is
a problem because normally, when we think of forces, or of things
like gravitational or magnetic fields, we take some notion like that
of a particle for granted. We understand the existence of a field or
force at some point in space in terms of the acceleration that would occur ifsome test particle were placed there. If there is a magnet on
the table, the existence of the magnetic field around it is a matter of
the way in which other `things' (particles) would tend to move if
they were put at various distances from it. In the familiar school experiments, iron filings take the role of test particles.