Forthcoming
in Chomsky and his Critics, edited by
Louise Antony and Norbert Hornstein (Blackwell 2002)
_____________________________________________________
Real
materialism[1] Galen Strawson
‘Trinculo
might have been referring to modern physics in the words, “This is the tune of
our catch, played by the picture of Nobody”.’ [Eddington][2]
Love
like Matter is/Much odder than we thought. [Auden][3]
_____________________________________________________
Materialism is the view that every real, concrete[4]
phenomenon[5]
in the universe is physical. It is a view about the actual universe, and for
the purposes of this paper I am going to assume that it is true.
It
has been characterized in other ways. David Lewis once defined it as
‘metaphysics built to endorse the truth and descriptive completeness of physics
more or less as we know it’,[6]
and this cannot be faulted as a terminological decision. But it seems unwise to
burden materialism—the view that every real concrete phenomenon in the universe
is physical—with a commitment to the
descriptive completeness of physics
more or less as we know it. There may be physical phenomena which physics (and
any non-revolutionary extension of it) cannot describe, and of which it has no
inkling, either descriptive or referential.[7]
Physics is one thing, the physical is another. ‘Physical’ is a natural-kind
term—it is the ultimate natural-kind term[8]—and
no sensible person thinks that physics has nailed all the essential properties
of the physical. Current physics is profoundly beautiful and useful, but it is
in a state of chronic internal tension.[9]
It may be added, with Russell and others, that although physics appears to tell
us a great deal about certain of the general structural or mathematical
characteristics of the physical, it fails to give us any further insight into
the nature of whatever it is that has these structural or mathematical
characteristics—apart from making it plain that it is utterly bizarre relative
to our ordinary conception of it.
It
is unclear exactly what this last remark amounts to (is it being suggested that
physics is failing to do something it could do?), but it already amounts to
something very important when it comes to what is known as the ‘mind-body
problem’. Many take this to be the problem of how mental phenomena can be
physical phenomena given what we already
know about the nature of the physical. But those who think this are already
lost. For the fact is that we have no
good reason to think that we know anything about the physical that gives us any
reason to find any problem in the idea that mental phenomena are physical
phenomena. If we consider the nature of our knowledge of the physical, we
realize that ‘no problem of irreconcilability arises’.[10]
Joseph Priestley saw this very clearly over two hundred years ago, and he was
not the first. Noam Chomsky reached essentially the same conclusion over thirty
years ago, and he was not the last.[11]
Most present-day philosophers take no notice of it and waste a lot of time as a
result: much of the present debate about the ‘mind-body’ problem is beside the
point.
I am going to use the plural-accepting,
count-noun form of the word ‘experience’ for talking of experiences
as things (events) that may (and presumably do) have non-experiential being as
well as experiential being. And I am going to reserve the adjective
‘experiential’ and the plural-lacking form of the noun ‘experience’ for talking
about the qualitative character that experiences have for those who have
them as they have them, where this qualitative character is considered wholly
independently of everything else. The phenomenon of experiential[12]
qualitative character is part of what exists—it is part of reality, whatever
its ontological category—and it is essential to have some unequivocal way of
referring to it and only to it.
One
could express this terminological proposal by saying that ‘experiential
phenomena’ and ‘experience’ (plural-lacking form) refer in a general way to:
that part of reality which one is left with when, continuing to live and think
and feel as one does, one engages in an old sceptical thought experiment and
imagines that the ‘external world’, including one’s own body, does not exist.
They refer to the part or aspect of reality one has to do with when one
considers experiences specifically and solely in respect of the experiential
qualitative character they have for those who have them as they have them, and
puts aside the fact that they may also be correctly describable in such
non-experiential terms as ‘a 70-20-30 Hertz coding triplet across the neurons
of area V4’.[13]
It
is easy to forget the force of this ruling, and I will mark it by giving
‘experiential’ and ‘experience’ capital letters.
3 Realistic materialism
Realistic materialists—realistic anybodys—must
grant that Experiential phenomena are real, concrete phenomena, for nothing in
this life is more certain.[14]
They must therefore hold that they are physical phenomena. It may sound odd to
use the word ‘concrete’ to characterize the qualitative character of
experiences of colour, gusts of depression, thoughts about diophantine
equations, and so on, but it isn’t, because ‘concrete’ simply means ‘not
abstract’. [15] For most
purposes one may take ‘concrete’ to be coextensive with ‘possessed of spatiotemporal
existence’, although this will be directly question-begging in some contexts.[16]
It
may also sound odd to use ‘physical’ to characterize mental phenomena like
Experiential phenomena: many materialists talk about the mental and the
physical as if they were opposed categories. But this, on their own view, is like talking about cows and animals as if
they were opposed categories. For every concrete phenomenon in the universe is
physical, according to materialists. So all mental phenomena, including Experiential
phenomena, are physical phenomena, according to materialists; just as all cows
are animals.
So
what are materialists doing when they talk, as they so often do, as if the
mental and the physical were entirely different? What they may mean to do is to
distinguish, within the realm of the physical, which is the only realm there
is, according to them, between the mental and the non-mental, or between the
Experiential and the non-Experiential; to distinguish, that is, between mental
(or Experiential) features of the physical, and non-mental (or
non-Experiential) features of the physical.[17]
It
is this difference that is in question when it comes to the ‘mind-body’
problem; materialists who persist in talking in terms of the difference between
the mental and the physical perpetuate the terms of the dualism they reject in
a way that is inconsistent with their own view. I use the words ‘mental’ and
‘non-mental’ where many use the words ‘mental’ and ‘physical’ simply because I
assume, as a (wholly conventional) materialist, that every real concrete
phenomenon is physical, and find myself obliged to put things in this way.[18]
There
is tremendous resistance to abandoning the old mental/physical terminology in
favor of the mental/non-mental, Experiential/non-Experiential terminology,
although the latter seems to be exactly what is required. Many think the old
terminology is harmless, and a few are not misled by it: they consistently use
‘physical’ to mean ‘non-mental physical’. But it sets up the wrong frame of
thought from the start, and I suspect that those who are never misled by it are
members of a small minority.
When
I say that the mental, and in particular the Experiential, is physical, and
endorse the view that ‘experience is really just neurons firing’, I mean
something completely different from what some materialists have apparently
meant by saying such things. I don’t mean that all aspects of what is going on,
in the case of conscious experience, can be described by current physics, or
some non-revolutionary extension of it. Such a view amounts to radical
‘eliminativism’ with respect to consciousness,[19]
and is mad. My claim is different. It is that the Experiential (considered just
as such)[20]—the feature
of reality we have to do with when we consider experiences specifically and
solely in respect of the Experiential character they have for those who have
them as they have them—that ‘just is’ physical. No one who disagrees with this
is a remotely realistic materialist.
When
aspiring materialists consider the living brain, in discussion of the
‘mind-body problem’, they often slide into supposing that the word ‘brain’
somehow refers only to the brain-as-revealed-by-current-physics. But this is a
mistake, for it refers just as it says, to the living brain, i.e. the living
brain as a whole, the brain in its total physical existence and activity.
Realistic—real—materialists must agree that the total physical existence and
activity of the brain of an ordinary, living person, considered over time, is constituted by Experiential phenomena
(if only in part) in every sense in which it is constituted (in part) by
non-Experiential phenomena characterizable by physics. A real (realistic)
materialist cannot think that there is something still left to say about
Experiential phenomena, once everything that there is to say about the physical
brain has been said.
4 Materialism further defined
Materialism, then, is the view that every
real concrete phenomenon is physical in every respect, but a little more needs
to be said, for Experiential phenomena—together with the subject of experience,
assuming that that is something extra—are the only real, concrete phenomena
that we can know with certainty to exist,[21]
and as it stands this definition of materialism doesn’t even rule out idealism—the
view that mental phenomena are the only real phenomena and have no non-mental
being—from qualifying as a form of materialism! Now there is a sense in which
this consequence of the definition is salutary (see e.g. §§14-15 below), but it
would none the less be silly to call an idealist view ‘materialism’. Russell is
right to say that ‘the truth about physical objects must be strange’,[22]
but it is reasonable to take materialism to be committed to the existence of
non-Experiential being in the universe, in addition to Experiential being, and
I shall do so in what follows.
It
is also reasonable to take materialism to involve the claim that every existing concrete phenomenon has
non-mental, non-Experiential being, whether or not it also has mental or Experiential
being. Applied to mental phenomena, then, materialism claims that each
particular mental phenomenon essentially has non-mental being, in addition to
mental being. This is, I think, the standard view.[23]
I
will assume, then, that all realistic materialists take it that there is both
mental and Experiential being and non-mental, non-Experiential being. Must all
realistic monists also take it that
there is non-mental, non-Experiential being? Many would say Yes, on the grounds
that it is not remotely realistic to suppose either that there is, or might be,
no non-mental or non-Experiential being at all. But the question of what it is
to be (metaphysically) realistic is far harder here than it is when it is
merely the existence of Experience that is in question. For the purposes of
this paper I will assume that any
realistic position does take it that there is non-mental or non-Experiential
being in addition to mental and Experiential being, for this assumption accords
with ordinary conceptions, and my main argument does not require me to
challenge it. But it is at best an assumption. Idealists, of course, reject the
assumption that realistic monism requires acknowledgement of non-mental,
non-Experiential phenomena, and I will enter a number of reservations along the
way.[24]
It
is clumsy to oscillate between ‘mental’ and ‘Experiential’, or constantly
double them up, and in the next few sections I will run the discussion in terms
of the mental/non-mental distinction (such as it is). This said, all my examples of mental phenomena will be
Experiential phenomena, for they suffice to make the relevant point and are, in
the present context, what matter most.
It
may be added that the reference of the term ‘Experiential’ is much clearer than
that of the essentially contestable term ‘mental’, and that the latter may in
the end deserve the treatment proposed for the term ‘physical’ in §15 below.
Nevertheless it seems best to begin in this way.[25]
I
will quote Russell—post-1926 Russell—frequently when discussing materialism,
for my views converge with his in certain respects, and he has been wrongly
ignored in recent discussion.[26]
He was still inclined to call himself a ‘neutral monist’ at that time, but he
is equally well read as a thoroughgoing materialist.[27]
He rejects materialism in name, pointing out that ‘matter has become as ghostly
as anything in a spiritualist séance’—it has, he says, disappeared ‘as a
“thing”’ and has been ‘replaced by emanations from a locality’[28]—,
but he grants that ‘those who would formerly have been materialists can still
adopt a philosophy which comes to much the same thing. They can say that the
type of causation dealt with in physics is fundamental, and that all events are
subject to physical laws’.[29]
And this, in effect, is what he does himself.[30]
5 ‘Mental’ and ‘non-mental’
It may seem odd to take ‘mental’ as the
basic positive term when characterizing materialism. But one is not a
thoroughgoing materialist if one finds it so. For all materialists hold that
every concrete phenomenon in the universe is physical, and they are neither
sensible nor realistic if they have any inclination to deny the concrete
reality of mental phenomena like Experiential phenomena.[31]
It follows that they have, so far, no reason to find it odd or biased to take
‘mental’ rather than ‘non-mental’ as the basic term.
—Surely it would be
better, even so, to start with some positive term ‘T’ for the non-mental
physical, and then define a negative term, ‘non-T’, to cover the mental
physical; or use a pair of independently positive terms?
There are two good reasons for taking
‘mental’ as the basic positive term, one terminological, the other
philosophical. The terminological reason is simply that we do not have a
convenient positive term for the non-mental (obviously we can’t use ‘physical’,
and there is no other natural candidate). The philosophical reason is very old:
it is that we have direct acquaintance with—know—fundamental features of the
mental nature of (physical) reality just in having experience in the way we do,
in a way that has no parallel in the case of any non-mental features of
(physical)[32] reality. We
do not have to stand back from experiences and take them as objects of
knowledge by means of some further mental operation, in order for there to be
acquaintance and knowing of this sort: the having is the knowing.[33]
This
point has often been questioned, but it remains immovable. Russell may
exaggerate when he says that ‘we know nothing
about the intrinsic quality of physical events except when these are mental events
that we directly experience’,[34]
or that ‘as regards the world in general, both physical and mental, everything that we know of its intrinsic
character is derived from the mental side’,[35]
for it is arguable that the spacetime character of the world is part of its
intrinsic character, and, further, that we may have some knowledge of this
spacetime character. I don’t think he exaggerates much, however. He is onto
something important, and the epistemological asymmetry between claims to
knowledge of Experiential being and claims to knowledge of non-Experiential
being is undeniable, however unfashionable.
The
asymmetry claim that concerns me is not the claim that all epistemic contact
with concrete reality involves experience, and that we are inevitably a further
step away from the thing with which we are in contact when it is a
non-Experiential phenomenon. It is, rather, the claim that we are acquainted
with reality as it is in itself, in
certain respects, in having Experience as we do. This second claim revolts
against the tendency of much current epistemology and philosophy of mind, but
there is no reason why it should trouble thoughtful materialists, and I will
offer a brief defence of it in §13. Here it is worth noting that it is fully
compatible with the view that there may also be fundamental things we don’t
know about matter considered in its Experiential being.[36]
6 Aside: ‘as it is in itself’
Does one need to defend the phrase ‘as it
is in itself’, when one uses it in philosophy? I fear one does, for some think
(incoherently) that it is somehow incoherent. Still, it is easy to defend. The
supposition that reality is in fact a certain way, whatever we can manage to
know or say about it, is obviously true. To be is to be somehow or other.
Nothing can exist or be real without being a certain way at any given time.[37]
And the way something is just is how it is in itself. This point is not
threatened by the suggestion that our best models of the behaviour of things
like photons credit them with properties that seem incompatible to us—e.g.
wave-like properties and particle-like properties. What we learn from this is
just that this is how photons affect us, given their intrinsic nature—given how
they are in themselves, and how we are in ourselves. We acquire no reason to
think (incoherently) that photons do not have some intrinsic nature at any
given time. Whatever claim anyone makes about the nature of reality—including
the claim that it has apparently incompatible properties—just is a claim about
the way it is. This applies as much to the Everett ‘many-worlds’ theory of
reality as to any other.
Some
think that what we learn from quantum theory is that there is, objectively, no
particular way that an electron or a photon is, at a given time. They confuse
an epistemological point about undecidability with a metaphysical claim about
the nature of things. The problem is not just that such a claim is
unverifiable. The problem is that it is incoherent. For whatever the electron’s
or photon’s weirdness (its weirdness-to-us: nothing is intrinsically weird),
its being thus weird just is the way it is.
So
we may talk without reservation of reality as it is in itself. Such talk
involves no (allegedly dubious) metaphysics of the Kantian kind. Its propriety
derives entirely and sufficiently from the thought that if a thing exists, it
is a certain way. For the way it is just is how it is in itself.
7 Structure and structured
So much, for the moment, for our
theoretical conception of the mental: it has some securely anchored, positive
descriptive content, and we can know that this is so; for whatever the best
general account of the mental, it includes Experiential phenomena in its scope;
and Experiential phenomena are not only indubitably real; they are also
phenomena part of whose intrinsic nature just is their Experiential character;
and their Experiential character is something with which we are directly
acquainted, however hard we may find the task of describing it in words. This
is so even if we can make mistakes about the nature of our experiences, and
even if we can do so even when we consider them merely in respect of their
(Experiential) qualitative character.[38]
It is so even if we differ dramatically among ourselves in the qualitative
character of our experiences, in ways we cannot know about.
Our
theoretical conception of the mental, then, has clear and secure descriptive
content. (Don’t ask for it to be put further into words; the anchoring is
sufficiently described in the last paragraph.) Our theoretical conception of
the non-mental, by contrast, remains, so far, a wholly negative concept. It
has, as yet, no positive descriptive content.
Can
anything be done about this? On one reading, Russell thinks not: the science of
physics is our fundamental way of attempting to investigate the non-mental
being of physical reality, and it cannot help us. ‘Physics is mathematical’, he
says, ‘not because we know so much about the physical world, but because we
know so little: it is only its mathematical properties that we can discover.
For the rest, our knowledge is negative’. ‘We know nothing about the intrinsic
quality of physical events except when these are mental events that we directly
experience’. On this view, neither physics nor ordinary experience of physical
objects give us any sort of knowledge of the intrinsic nature of non-mental
reality.[39]
Is
Russell right? Something needs to be said about his use of the word
‘intrinsic’. It is potentially misleading, and it helps to consider other ways
in which he puts the point. Thus he talks regularly of the ‘abstractness’ of
physics. The knowledge it gives is, he says, ‘purely formal’. It reveals the
abstract ‘structure’ of physical phenomena while saying nothing about their
‘quality’....[40]
I
am not sure that the distinction between structure and quality is clear, or
fundamental in such a way that it holds ‘all the way down’,[41]
but (putting that doubt aside) it seems that the fundamental distinction that
Russell has in mind can be expressed by saying that it is a distinction between
how X is structurally disposed and what X is apart from (over and above) its
structural disposition.[42]
Physics gives the structure, but not the structure-transcendent nature, of the
thing that has the structure. If we say that truths about how X is structurally
disposed have purely structure-specifying
content, while truths about what X is over and above its structural disposition
also have structure-transcendent
content, or, more simply, non-structural
content, then we may say that ‘non-structural’ covers everything that Russell
has in mind when he talks of the ‘intrinsic’ nature of things.[43]
One
might dramatize Russell’s idea by saying that physics can be thought of as a
formal system which remains, in a peculiar sense, an uninterpreted formal system, even though we know that it applies to something=x—reality, the
universe—and even though it is elaborated specifically in causal response to x.
On this ‘Ramseyfied’ view, we may suppose that the universe has features that
are structurally isomorphic to the
structures delineated in the equations of physics, but we have no account of
the non-structural nature of the thing that has the structure(s) in question.[44]
So
we are (to pursue the metaphor) in the peculiar position of having a known,
concrete application (and so, in one
sense, an interpretation) for a
formal system, without that application constituting a model (in the sense of model-theoretic semantics) that can confer
positive descriptive meaning on its terms. In being the subject matter of
physics, the universe provides it with a merely referential model or object, of
which it gives a merely structure-specifying description. Physics is about the physical, and may give a
correct abstract representation of its structural disposition as far as it
goes; but it does not and cannot tell us anything about what the physical
actually is, over and above the fact that it exemplifies a certain formal
structure.[45]
8 The non-mental—space
Back now to the question whether physics
can endow our general theoretical conception of the non-mental with any
positive descriptive (not merely referential) content. Russell in 1927 thinks
not. I disagree because correct structural description of a thing is already
description of a feature of its intrinsic nature. But this disagreement is
merely terminological, and the real question is this: Can one go any further
than structure-specifying content, when attempting to give a satisfactory
theoretical characterization of the non-mental? Again, Russell in 1927 thinks
not. It seems to me, however, that we may be able to go a little further. For I
think that our ordinary conception of space may get something fundamental right
about the nature of reality as it is in itself, and hence about the intrinsic
nature of reality—something that survives even after the finite-but-unbounded
curved gravity-constituting spacetime of relativity theory (or the ten- or
eleven- or twelve-dimensional spacetime of one of the leading versions of
string theory) has been granted to be closer to the truth.
I
am tempted to hold up my hands, like G. E. Moore, and to consider, not my
hands, but the space—by which I mean only the spatial extension[46]—between
them, and to say: ‘This is space (spatial extension), and it is real, and I
know its nature, in some very fundamental respect, whatever else I do not know
about it or anything else (e.g. the fact that it is an aspect of spacetime)’.
On this view the ordinary concept of space, or indeed the concept of spacetime,
in which (I claim) a fundamental feature of our ordinary conception of space
survives, has correct non-structural descriptive content. It does not relate
only to ‘what we may call the causal skeleton of the world’,[47]
if to say this is to say that it does not capture any aspect of the
non-structural nature of the world. It has non-structural content, and can
transmit this content to our more general conception of the non-mental.[48]
Russellians
may object as follows. ‘This line of thought is profoundly natural, but it
depends on a fundamentally false imagining. It involves the conflation of
‘objective’ spatial extension, spatial extension ‘as it is in itself’ (where
this is taken as a merely referential, structural-equivalence-class specifying
term with no pretension to non-structural content) with the phenomenological
space (or spaces) associated with perception. It involves an almost
irresistible but entirely fatal failure to ‘realize what an abstract affair
form really is’.[49] All those,
like yourself, who think that it is viable are ‘guilty, unconsciously and in
spite of explicit disavowals, of a
confusion in their imaginative picture’ of reality.[50]
I
think that some of those who take this line may be suffering from excessive
empiricism. They take it that the notion of spatial extension—or indeed
shape—that we possess is essentially informed by the character of our sensory
experiences, and in this I think they are mistaken. It may well be true that
sensory experiences of specific kinds are necessary for the acquisition of
concepts like shape or space, in the case of beings like
ourselves.[51] Such
concepts can nevertheless float free of the different possible sensory bases of
their acquisition and subsequent deployment, without ipso facto becoming
‘merely’ formal or structure-specifying in character. It is easy to see that grasp
of the content of shape (say)
does not require essential reference to any specific sensory experience. It
suffices to point out that exactly the same concept of shape—i.e. the concept of shape, for there is only
one—can plausibly be supposed to be fully masterable by two different creatures
A and B on the basis of sensory experiences in entirely different sensory
modalities familiar to us—sight and touch.[52]
One has to endorse a rather crude form of meaning-empiricism or
concept-empiricism to suppose that A and B do not—cannot—have the same concept,
as they do geometry together. A concept is not a faint copy or transform of a
sensory experience. It is, precisely, a concept.
That’s
one point. Another, crucial in this context, is that the concept of shape or
space that A and B have in common is not an entirely abstract or purely formal
concept, as the supporters of Russell seem to suggest. There is more to A and B
sharing the specific concept shape
or space than there is to their
sharing mastery of the principles of an uninterpreted formal system that is in
fact suitable for the expression of shape configurations or spatial relations
although they know it only as an uninterpreted formal system. It is precisely
because pure form is such a very
‘abstract affair’, as Russell says, that the concept of shape or space that A
and B can have in common in spite of their different sensory experiences cannot
be supposed to be a matter of pure form. To think that it is a matter of pure
form is to miss out precisely their grasp of the spatiality of space—of that which makes their grasp of the concept
of space more than grasp of (say) an abstract metric. The concept has
non-structural content.
It is true that this content is abstract in
one sense: it is abstract relative to all the particularities of sensation, in
a way that is sufficiently indicated by reference to the fact that different
creatures can acquire it (the very same concept) on the basis of experience in
entirely different sensory modalities. It is indeed, and essentially, a non-sensory concept.[53]
But it is not purely abstract in Russell’s sense, because (to repeat) it
involves grasp of the spatiality—rather than what one might call the mere
abstract dimensionality—of space.[54]
Spatiality is not abstract dimensionality: the nature of abstract
dimensionality can be fully captured by a purely mathematical representation;
the nature of spatiality cannot. ***One can give a purely mathematical
representation of the dimensionality of space, but it won’t distinguish space from any other possible
three-dimensional ‘space’, e.g. the emotional vector space of a species that
have just three emotions, love, anger, and despair.
Obviously questions arise about the precise
nature of the non-structural content of concepts like shape and space,
about what it is, exactly, to grasp the spatiality of space, given that shape and space may be fully shared by A, B, superbats, and others. But
in the present context I am inclined just to hold up my hands again.[55]
Russellians
may be unimpressed. Michael Lockwood, in particular, is sympathetic to the idea
that knowledge of spacetime structure is not knowledge of any feature of the
‘intrinsic’ or non-structural nature of reality. In doing physics, Lockwood
says, we may grasp the abstract structure exemplified by space while having ‘no
conception of its content: i.e. what it is, concretely, that fleshes out this
structure. (For all we know, on this view, Henry More and Newton may be right
in equating space with God’s sensorium!)’[56]
But
I am prepared to grant this. I am prepared to grant that we cannot rule out the
possibility that space is God’s sensorium,[57]
or something even more unknown, and that there is therefore a sense in which we
may have no idea of what it is that ‘fleshes out’ the abstract structure
exemplified by space. For it may still be true that one grasps something
fundamental about the non-structural nature of space in thinking of it as
having, precisely, spatiality, rather than mere abstract dimensionality. If
space is God’s sensorium, so be it: God’s sensorium may really have the
property of spatiality. Between a fat-free, purely mathematical and thus wholly
abstract representation of the structure of space and a partly
structure-transcending conception of space as God’s sensorium (or some such)
lies a third option: an ostensibly less rich but still structure-transcending
conception of space as specifically spatial (hands held up) in its
dimensionality. Some may think this a fine point, but it is (I take it) a huge
step away from Russell’s claim that we know nothing
about the intrinsic quality of non-mental events.[58]
I
am not claiming that we do know something about the non-structural nature of
space, only that we may (I hold up my hands, I move them apart—but my sense of
the vulnerability of this claim has increased since I wrote this paper in
1997). This claim allows, as it should, that there may well be more to space
than we can know. space, like physical, is a natural-kind concept,
and there are some atrociously good reasons for thinking that there is more to
space than we know or can fully understand. In addition to the (already
weighty) points that physical space is non-Euclidean, and is itself something
that is literally expanding,[59]
and the non-locality results,[60]
and questions about the nature of the vacuum, and widespread agreement that
‘there is no good a priori reason why space should be a continuum’,[61]
I for one still can’t fully understand how space and time can be interdependent
in the way that they demonstrably are. We are also told on very good authority
that gravity is really just a matter of the ‘curvature’ of space, and that
string theory is an immensely promising theory of matter (especially after the
‘second superstring revolution’ and the growth of M-theory, and especially when
it comes to understanding gravity) that entails that there are at least ten
spatial dimensions….
These
points reopen the connection to the mind-body problem. For as they pile up, one
can’t reputably hold on to the old, powerful-seeming Cartesian intuition that
there is a ‘deep repugnance’ or incompatibility between the nature of conscious
experience and the nature of spatial extension—the intuition that ‘the mental
and the spatial are mutually exclusive categories’.[62]
We have direct acquaintance with fundamental features of conscious
experience—Experiential features—just in having it; but we really have no good
reason to think that we know enough about the nature of space—or rather, about
the nature of matter-in-space-considered-in-so-far-as-it-has-non-mental-being—to
be able to assert that there is any repugnance.[63]
And if conscious experience is in time, as almost everyone agrees, then it is
in spacetime, given the way in which space and time are demonstrably
interdependent—in which case it is in space in every sense in which it is in
time.
Note
that it follows that even if our notion of space can confer some non-structural
content on our best theoretical conception of the non-mental, it cannot confer
any content that is guaranteed to distinguish it from any fully articulated
theoretical conception of the mental, although we still intuitively feel it to
fit with the former conception in a way in which we don’t feel it to fit with
the latter.[64]
9 The non-mental—spin, mass, and charge
I have proposed that our theoretical
conception of the non-mental may be able to acquire some non-structural content
from its first lieutenant, the concept of space. Can it acquire any more? Well,
I think that our more particular spatial concepts of shape, size, position,
distance, and local motion (I raise my hands and bring them together) may also get something right about
reality as it is in itself, and so contribute to the non-structural content of
our general theoretical conception of the non-mental; I think Locke may be
essentially right in his view that some of our ideas of primary qualities
correctly represent how things are in themselves, although his account needs
recasting.[65] It may also
be that our ordinary conception of time gets something right about the nature
of reality (both Experiential and non-Experiential)—even if we need to conceive
time as part of spacetime in order to think about it properly. I just don’t
know.[66]
Going
on from space, time, extension, shape, position, distance, and motion, in the
attempt to give a positive characterization of the non-mental, one may want to
mention properties like spin, mass, charge, gravitational attraction, ‘colour’
and ‘flavour’ (in the quantum-theoretic sense). But one will have to bear in
mind that our grasp of these things—any grasp of them over and above that which
is conveyed by their intimate relation to ***concepts of space and time—is
expressed merely in equations;[67]
and the truth in Russell’s remark that physics is mathematical not because we
know so much about the physical world, but because we know so little. So
although I like to think that ***concepts of space and time carry
non-structural content, I do not think this can be true of any of these other
concepts considered independently of their relations to ***concepts of space
and time. Here Russell is right: we know nothing of the non-mental
non-structural nature of—for example—electrical phenomena apart from their
spacetime structure; all we have are equations.[68]
But
even if knowledge of spacetime structure is all we have, in the way of
non-structural knowledge of the nature of the non-mental, it makes a huge
difference to the case. Consider the difference between a characterization of
the forces of electrical attraction and repulsion in which their spatial
character (the way they decrease with increasing distance) is given a purely
mathematical, abstract-dimensional interpretation, and one in which it is given
a genuinely spatial interpretation. Consider any account of anything in which
time relations have a merely mathematical abstract representation, and one in
which the temporality of time is somehow represented.
10 Hens’ eggs
I want now to give a further
characterization of what it is to be a genuine materialist. But I must first
answer one more objection that occurs to many.
—It seems to follow,
from your claim that we have no knowledge of the non-structural, intrinsic or
as we may say N-intrinsic nature of
things, that we cannot know that there are tables and chairs and hens and hens’
eggs and ‘that hens’ eggs are generally laid by hens’.[69]
But this is a chair I’m sitting in, and it’s made of wood, and this is a hen,
and this is a hen’s egg, and this hen laid it. These are all facts I know, and
they are N-intrinsic facts—ultimate, absolute truths—about the nature of
reality. They must be included in any true and full account of the history of
the universe.
My reply to this objection is similar to
Moore’s a hundred years ago. I agree that we know many such truths, but I take
it, as a materialist, that hens are wholly made of the fundamental constituents
of matter that physics discusses, and that when we consider our knowledge of
these fundamental constituents we encounter the crucial and entirely general
sense in which we know nothing about the fundamental N-intrinsic nature of
matter. As far as I can see, this ignorance is entirely compatible with the
sense in which we do have knowledge of the N-intrinsic of reality in knowing
that there are hens, and what hens are, and what wood is, and so on. And this
compatibility is no more surprising than the fact that I can know that this is
a statue without knowing what it is made of.
—But we know what hens
are made of—carbon, hydrogen, and oxygen, mostly—and we know what carbon,
hydrogen, and oxygen are made of—electrons and quarks with various
characteristics. Physics gives us knowledge of the properties of these things.
If you think that it fails to give us any knowledge of their ultimate,
N-intrinsic nature that’s because you think that a thing is more than its
properties. But that’s just bad old metaphysics. A thing is not in any sense
more than its properties.
I agree that there is an irredeemably
difficult but inescapable sense in which it is true to say that a thing is not
more than its properties—I agree that ‘in their relation to the object, the
properties are not in fact subordinated to it, but are the way of existing of
the object itself’[70]—but
the present claim is not that a concrete phenomenon must be more than its
properties, but that it must be more than its purely formal or structural
properties. If you say that this is more bad metaphysics, a yearning for lumpen
stuff, our disagreement will be plain. My reply will be that you have evidently
forgotten ‘what an abstract affair form really is’. A concrete phenomenon must
be more than its purely formal or structural properties, because these,
considered just as such, have a purely abstract mathematical representation,
and are, concretely, nothing—nothing at all. It is true that we get out of the
realm of the purely abstract when we add in spatiotemporal properties, on my
account, but a thing’s non-structural properties can’t consist only in its
spatiotemporal properties—at least so long as spacetime is conceived merely as
a dimensional manifold with no physical or substantial nature.[71]
Here,
then, we return to the point that—the sense in which—we have no knowledge of
the N-intrinsic nature of things in spite of the sense in which it is true to
say that we know what hens and hens’ eggs are.
11 True materialism
I have suggested that our general
theoretical conception of the mental has substantial non-structural descriptive
content, because we have acquaintance with fundamental features of the mental
nature of reality just in having experience in the way we do. Our general
theoretical conception of the non-mental has substantial structure-specifying
content, and I have suggested, with some hesitation, that it may also have
crucial and correct non-structural
content deriving from spatiotemporal concepts. Apart from this, though, it is
arguable (subject to note 48) that we know nothing about the intrinsic or
non-structural nature of non-mental reality.
With
this in place, we may ask what is to be a genuine materialist. The first thing
to do is to intone once more that realistic or real materialism entails full
acknowledgement of the reality of Experiential phenomena: they are as real as
rocks, hence wholly physical, strictly on a par with anything that is correctly
characterized by physics.[72]
They are part of fundamental reality, whatever is or is not the case.
It
follows that current physics, considered as a general account of the general
nature of the physical, is like Othello
without Desdemona: it contains only predicates for non-Experiential being, so it
cannot characterize Experiential being at all (recall the definition in §2). It
cannot characterize a fundamental feature of reality at all.
No
one who doubts this is a true materialist. Partly for this reason, I think that
genuine, reflective endorsement of materialism is a considerable achievement
for anyone who has had a standard modern Western education. Materialism must at
first provoke a feeling of deep bewilderment in anyone contemplating the
question ‘What is the nature of the physical?’ The occurrence of such a feeling
is diagnostic of real engagement with the materialist hypothesis, real
engagement with the thought that Experiential phenomena are physical phenomena
just like extension phenomena and electrical phenomena in so far as they are correctly
characterized by physics (or indeed common sense). I think Russell is
profoundly right when he says that most are ‘guilty, unconsciously and in spite
of explicit disavowals, of a confusion in their imaginative picture of matter’.
I
suspect that some will be unable to shake off the confusion, although Locke
made the crucial move long ago. Some may say that modern science has changed
the situation radically since Locke’s time. It has—but only in so far as it has
massively reinforced Locke’s point.
Perhaps
I am generalizing illegitimately from my own experience, revealing my own
inadequacy rather than the inadequacy of recent discussion of the ‘mind-body’
problem, but I don’t think so. Materialism requires concerted meditative
effort. Russell recommends ‘long reflection’.[73]
If one hasn’t felt a kind of vertigo of astonishment, when facing the thought,
obligatory for all materialists, that consciousness is a wholly physical
phenomenon in every respect, including every Experiential respect—a sense of
having been precipitated into a completely new confrontation with the utter
strangeness of the physical (the real) relative to all existing common-sense
and scientific conceptions of it—, then one hasn’t begun to be a thoughtful
materialist. One hasn’t got to the starting line.[74]
Some
may find that this feeling recurs each time they concentrate on the mind-body
problem. Others may increasingly think themselves—quietistically,
apophatically, pragmatically, intuitively—into the unknownness of the
(non-mental) physical in such a way that they no longer experience the fact
that mental and non-mental phenomena are equally physical as involving any
clash. At this point ‘methodological naturalism’—the methodological attitude to
scientific enquiry into the phenomena of mind recommended by Chomsky—will
become truly natural for them, as well as correct.[75]
I think it is creeping over me. But recidivism is to be expected: the
powerfully open state of mind required by true materialism is hard to achieve
as a natural attitude to the world. It involves a profound reseating of one’s
intuitive theoretical understanding of things.[76]
I
say ‘intuitive theoretical understanding’, but it isn’t as if there is any
other kind, when the stress falls on the word ‘understanding’. For (briefly)
what we think of as real understanding
of a natural phenomenon is at bottom a feeling,
and it is always and necessarily relative to other things one
just takes for granted, finds intuitive, feels comfortable with. This is true
in science as it is in common life. I feel I fully understand why this tower
casts this shadow in this sunlight, given what I take for granted about the
world (I simply do not ask why light should do that, of all things, when it hits stone). I may also feel I
understand—see—why this billiard ball does this
when struck in this way by that billiard ball. But in this case there is
already a more accessible sense in which I don’t really understand what is going on, and it is an old point that if I were
to ask for and receive an explanation, in terms of impact and energy transfer,
this would inevitably invite further questions about the nature of impact and
energy transfer, starting a series of questions and answers that would have to
end with a reply that was not an explanation but rather had the form ‘Well,
that’s just the way things are’.[77]
The
true materialist outlook may become natural for some, then, but many will find
they can maintain it only for relatively short periods of time. It is not a
small thing. To achieve it is to have evacuated one’s natural and gripping
common-sense ± science-based conception of the nature of the physical of every
element that makes it seem puzzling that Experiential phenomena are physical. I
think it is to be at ease with the idea that consciousness is a form of matter.[78]
It
can help to perform special acts of concentration—focusing one’s thought on
one’s brain and trying to hold fully in mind the idea that one’s experience as
one does so is part of the physical being of the brain (part of the physical being
of the brain that one may be said to be acquainted with as it is in itself, at
least in part, because its being as it is for one as one has it just is what it
is in itself, at least in part). It is worth trying to sustain this—it is part
of doing philosophy—, forcing one’s thought back to the confrontation when it
slips. At first one may simply encounter the curious phenomenological character
of the act of concentration, but it is useful to go on—to engage, for example,
in silent, understanding-engaging subvocalizations of such thoughts as ‘I am
now thinking about my brain, and am thinking that this experience I am now
having of this very thinking—and this subvocalization—is part of the physical
activity and being of my brain.’ It is also useful to look at others, including
young children, as they experience the world, and to think of the
common-or-garden matter that is in their heads (hydrogen, oxygen, carbon, iron,
potassium, sodium, and so on). It is useful to listen to music, and focus on
the thought that one’s auditory experience is a form of matter.[79]
12 Knowledge of ignorance
Finding it deeply puzzling how something
could be physical is not the same as finding something that one takes to be
physical deeply puzzling. It is often said that quantum theory is deeply
counterintuitive—e.g. in its description of the wave-like and particle-like
behaviour of fundamental particles, but no one seems to find it puzzling to
suppose that it deals wholly with physical phenomena.[80]
The
main reason for this seems to be as follows: wave
and particle engage smoothly with
standard physics concepts of shape, size, position, motion, and so on. There
is, so far, a clear sense in which the two concepts are theoretically homogeneous, or at least non-heterogeneous; they operate
on the same, single conceptual playing field of physics.[81]
But when we try to integrate conscious-experience terms with the terms of
physics (and common-sense physics), we find that they entirely lack any such
felt theoretical homogeneity, or non-heterogeneity. To this extent, they force
constantly renewed bewilderment—in a way quite different from the way in which
quantum-mechanical phenomena do—on materialists who like to think they have some sort of coherent, theoretically
unified understanding of the overall nature of the physical, however general
that understanding may be, and however incomplete in its details.
But
this is the central mistake: to think that one has some sort of theoretically
unified understanding of the overall nature of the physical. Once one realizes
that this cannot be true, if materialism is true, things change.[82]
It begins to look as if there is actually less
difficulty in the suggestion that physical phenomena have both Experiential and
non-Experiential being than in the suggestion that photons (e.g.) behave both
like particles and waves. For in the case of Experiential terms and
non-Experiential terms there is no direct clash of concepts of the sort that
occurs in the case of the wave-particle duality. Being a wave is incompatible
with being a particle, but there is nothing in the possession of
non-Experiential being that we know to be intrinsically inimical to the
possession of Experiential being: we simply do not know enough about the nature
of non-Experiential being to have any good reason to suppose that this might be
so. Thus the Experiential terms and the non-Experiential terms do not in fact actively clash, as the wave and particle
terms do. Rather, they fail to connect or engage. One is making progress as a
materialist when one has lost all sense of an active clash. It has no
scientific or philosophical justification. As Russell says, ‘the physical [sc
non-mental] world is only known as regards certain abstract features of its
space-time structure—features which, because of their abstractness, do not
suffice to show whether the physical world is, or is not, different in
intrinsic character from the world of mind’.[83]
Arnauld made the essential point in 1641, in
his comments on Descartes’s Meditations,
and he was not the first.[84]
Locke in 1690 ‘did not apprehend that there was any real inconsistency between
the known properties of body, and those that have generally been referred to
mind’.[85]
Algarotti observes in 1737 that
we are as yet but Children in this vast
Universe, and are very far from having a compleat Idea of Matter; we are
utterly unable to pronounce what Properties are agreeable to it, and what are
not,[86]
and Hume in 1739 shows a very clear understanding of the point.[87] Priestley in 1777 argues, with unanswerable force, and by appeal to a scientific conception of the physical that (in essence) still holds good today, ‘that we have no reason to suppose that there are in man two substances so distinct from each other as have been represented’.[88] Kant concurs in 1781, although his special terms of debate preclude him from agreeing directly with Priestley’s further materialist claim that ‘mind ... is not a substance distinct from the body, but the result of corporeal organization’; that ‘in man [thought] is a property of the nervous system, or rather of the brain’; that ‘sensation and thought do necessarily result from the organization of the brain’.[89] The quality of the mind-body debate is in many ways lower today than any oth