perception are not independent of being perceived. But even if this be
the case, it may nevertheless also happen that there are purely
physical causal laws determining the occurrence of objects which are
perceived by means of other objects which perhaps are not perceived.
In that case, in regard to such causal laws objects of perception will
be independent of being perceived. Thus the question whether objects
of perception are independent of being perceived is, as it stands,
indeterminate, and the answer will be yes or no according to the
method adopted of making it determinate. I believe that this confusion
has borne a very large part in prolonging the controversies on this
subject, which might well have seemed capable of remaining for ever
undecided. The view which I should wish to advocate is that objects of
perception do not persist unchanged at times when they are not
perceived, although probably objects more or less resembling them do
exist at such times; that objects of perception are part, and the only
empirically knowable part, of the actual subject-matter of physics,
and are themselves properly to be called physical; that purely
physical laws exist determining the character and duration of objects
of perception without any reference to the fact that they are
perceived; and that in the establishment of such laws the propositions
of physics do not presuppose any propositions of psychology or even
the existence of mind. I do not know whether realists would recognise
such a view as realism. All that I should claim for it is, that it
avoids difficulties which seem to me to beset both realism and
idealism as hitherto advocated, and that it avoids the appeal which
they have made to ideas which logical analysis shows to be ambiguous.
A further defence and elaboration of the positions which I advocate,
but for which time is lacking now, will be found indicated in my book
on _Our Knowledge of the External World_.[22]
The adoption of scientific method in philosophy, if I am not mistaken,
compels us to abandon the hope of solving many of the more ambitious
and humanly interesting problems of traditional philosophy. Some of
these it relegates, though with little expectation of a successful
solution, to special sciences, others it shows to be such as our
capacities are essentially incapable of solving. But there remain a
large number of the recognised problems of philosophy in regard to
which the method advocated gives all those advantages of division into
distinct questions, of tentative, partial, and progressive advance,
and of appeal to principles with which, independently of temperament,
all competent students must agree. The failure of philosophy hitherto
has been due in the main to haste and ambition: patience and modesty,
here as in other sciences, will open the road to solid and durable
progress.
FOOTNOTES:
[19] Bosanquet, _Logic_, ii, p. 211.
[20] _Some Problems of Philosophy_, p 124.
[21] _First Principles_ (1862), Part II, beginning of chap. viii.
[22] Open Court Company, 1914.
VII
THE ULTIMATE CONSTITUENTS OF MATTER[23]
I wish to discuss in this article no less a question than the ancient
metaphysical query, "What is matter?" The question,
"What is matter?"
in so far as it concerns philosophy, is, I think, already capable of
an answer which in principle will be as complete as an answer can hope
to be; that is to say, we can separate the problem into an essentially
soluble and an essentially insoluble portion, and we can now see how
to solve the essentially soluble portion, at least as regards its main
outlines. It is these outlines which I wish to suggest in the present
article. My main position, which is realistic, is, I hope and believe,
not remote from that of Professor Alexander, by whose writings on this
subject I have profited greatly.[24] It is also in close accord with
that of Dr. Nunn.[25]
Common sense is accustomed to the division of the world into mind and
matter. It is supposed by all who have never studied philosophy that
the distinction between mind and matter is perfectly clear and easy,
that the two do not at any point overlap, and that only a fool or a
philosopher could be in doubt as to whether any given entity is mental
or material. This simple faith survives in Descartes and in a
somewhat modified form in Spinoza, but with Leibniz it begins to
disappear, and from his day to our own almost every philosopher of
note has criticised and rejected the dualism of common sense. It is my
intention in this article to defend this dualism; but before defending
it we must spend a few moments on the reasons which have prompted its
rejection.
Our knowledge of the material world is obtained by means of the
senses, of sight and touch and so on. At first it is supposed that
things are just as they seem, but two opposite sophistications soon
destroy this naïve belief. On the one hand the physicists cut up
matter into molecules, atoms, corpuscles, and as many more such
subdivisions as their future needs may make them postulate, and the
units at which they arrive are uncommonly different from the visible,
tangible objects of daily life. A unit of matter tends more and more
to be something like an electromagnetic field filling all space,
though having its greatest intensity in a small region.
Matter
consisting of such elements is as remote from daily life as any
metaphysical theory. It differs from the theories of metaphysicians
only in the fact that its practical efficacy proves that it contains
some measure of truth and induces business men to invest money on the
strength of it; but, in spite of its connection with the money market,
it remains a metaphysical theory none the less.
The second kind of sophistication to which the world of common sense
has been subjected is derived from the psychologists and physiologists. The physiologists point out that what we see depends
upon the eye, that what we hear depends upon the ear, and that all our
senses are liable to be affected by anything which affects the brain,
like alcohol or hasheesh. Psychologists point out how much of what we
think we see is supplied by association or unconscious inference, how
much is mental interpretation, and how doubtful is the residuum which
can be regarded as crude datum. From these facts it is argued by the
psychologists that the notion of a datum passively received by the
mind is a delusion, and it is argued by the physiologists that even if
a pure datum of sense could be obtained by the analysis of experience,
still this datum could not belong, as common sense supposes, to the
outer world, since its whole nature is conditioned by our nerves and
sense organs, changing as they change in ways which it is thought
impossible to connect with any change in the matter supposed to be
perceived. This physiologist's argument is exposed to the rejoinder,
more specious than solid, that our knowledge of the existence of the
sense organs and nerves is obtained by that very process which the
physiologist has been engaged in discrediting, since the existence of
the nerves and sense organs is only known through the evidence of the
senses themselves. This argument may prove that some reinterpretation
of the results of physiology is necessary before they can acquire
metaphysical validity. But it does not upset the physiological
argument in so far as this constitutes merely a _reductio ad absurdum_
of naïve realism.
These various lines of argument prove, I think, that some part of the
beliefs of common sense must be abandoned. They prove that, if we take
these beliefs as a whole, we are forced into conclusions which are in
part self-contradictory; but such arguments cannot of themselves
decide what portion of our common-sense beliefs is in need of
correction. Common sense believes that what we see is physical,
outside the mind, and continuing to exist if we shut our eyes or turn
them in another direction. I believe that common sense is right in
regarding what we see as physical and (in one of several possible
senses) outside the mind, but is probably wrong in supposing that it
continues to exist when we are no longer looking at it.
It seems to me
that the whole discussion of matter has been obscured by two errors
which support each other. The first of these is the error that what we
see, or perceive through any of our other senses, is subjective: the
second is the belief that what is physical must be persistent.
Whatever physics may regard as the ultimate constituents of matter, it
always supposes these constituents to be indestructible.
Since the
immediate data of sense are not indestructible but in a state of
perpetual flux, it is argued that these data themselves cannot be
among the ultimate constituents of matter. I believe this to be a
sheer mistake. The persistent particles of mathematical physics I
regard as logical constructions, symbolic fictions enabling us to
express compendiously very complicated assemblages of facts; and, on
the other hand, I believe that the actual data in sensation, the
immediate objects of sight or touch or hearing, are extra-mental,
purely physical, and among the ultimate constituents of matter.
My meaning in regard to the impermanence of physical entities may
perhaps be made clearer by the use of Bergson's favourite illustration
of the cinematograph. When I first read Bergson's statement that the
mathematician conceives the world after the analogy of a cinematograph, I had never seen a cinematograph, and my first visit to
one was determined by the desire to verify Bergson's statement, which
I found to be completely true, at least so far as I am concerned.
When, in a picture palace, we see a man rolling down hill, or running
away from the police, or falling into a river, or doing any of those
other things to which men in such places are addicted, we know that
there is not really only one man moving, but a succession of films,
each with a different momentary man. The illusion of persistence
arises only through the approach to continuity in the series of
momentary men. Now what I wish to suggest is that in this respect the
cinema is a better metaphysician than common sense, physics, or
philosophy. The real man too, I believe, however the police may swear
to his identity, is really a series of momentary men, each different
one from the other, and bound together, not by a numerical identity,
but by continuity and certain intrinsic causal laws. And what applies
to men applies equally to tables and chairs, the sun, moon and stars.
Each of these is to be regarded, not as one single persistent entity,
but as a series of entities succeeding each other in time, each
lasting for a very brief period, though probably not for a mere
mathematical instant. In saying this I am only urging the same kind of
division in time as we are accustomed to acknowledge in the case of
space. A body which fills a cubic foot will be admitted to consist of
many smaller bodies, each occupying only a very tiny volume; similarly
a thing which persists for an hour is to be regarded as composed of
many things of less duration. A true theory of matter requires a
division of things into time-corpuscles as well as into space-corpuscles.
The world may be conceived as consisting of a multitude of entities
arranged in a certain pattern. The entities which are arranged I shall
call "particulars." The arrangement or pattern results from relations
among particulars. Classes or series of particulars, collected
together on account of some property which makes it convenient to be
able to speak of them as wholes, are what I call logical constructions
or symbolic fictions. The particulars are to be conceived, not on the
analogy of bricks in a building, but rather on the analogy of notes
in a symphony. The ultimate constituents of a symphony (apart from
relations) are the notes, each of which lasts only for a very short
time. We may collect together all the notes played by one instrument:
these may be regarded as the analogues of the successive particulars
which common sense would regard as successive states of one "thing."
But the "thing" ought to be regarded as no more "real"
or
"substantial" than, for example, the rôle of the trombone. As soon as
"things" are conceived in this manner it will be found that the
difficulties in the way of regarding immediate objects of sense as
physical have largely disappeared.
When people ask, "Is the object of sense mental or physical?" they
seldom have any clear idea either what is meant by
"mental" or
"physical," or what criteria are to be applied for deciding whether a
given entity belongs to one class or the other. I do not know how to
give a sharp definition of the word "mental," but something may be
done by enumerating occurrences which are indubitably mental:
believing, doubting, wishing, willing, being pleased or pained, are
certainly mental occurrences; so are what we may call experiences,
seeing, hearing, smelling, perceiving generally. But it does not
follow from this that what is seen, what is heard, what is smelt, what
is perceived, must be mental. When I see a flash of lightning, my
seeing of it is mental, but what I see, although it is not quite the
same as what anybody else sees at the same moment, and although it
seems very unlike what the physicist would describe as a flash of
lightning, is not mental. I maintain, in fact, that if the physicist
could describe truly and fully all that occurs in the physical world
when there is a flash of lightning, it would contain as a constituent
what I see, and also what is seen by anybody else who would commonly
be said to see the same flash. What I mean may perhaps be made plainer
by saying that if my body could remain in exactly the same state in
which it is, although my mind had ceased to exist, precisely that
object which I now see when I see the flash would exist, although of
course I should not see it, since my seeing is mental.
The principal
reasons which have led people to reject this view have, I think, been
two: first, that they did not adequately distinguish between my seeing
and what I see; secondly, that the causal dependence of what I see
upon my body has made people suppose that what I see cannot be
"outside" me. The first of these reasons need not detain us, since the
confusion only needs to be pointed out in order to be obviated; but
the second requires some discussion, since it can only be answered by
removing current misconceptions, on the one hand as to the nature of
space, and on the other, as to the meaning of causal dependence.
When people ask whether colours, for example, or other secondary
qualities are inside or outside the mind, they seem to suppose that
their meaning must be clear, and that it ought to be possible to say
yes or no without any further discussion of the terms involved. In
fact, however, such terms as "inside" or "outside" are very ambiguous.
What is meant by asking whether this or that is "in" the mind? The
mind is not like a bag or a pie; it does not occupy a certain region
in space, or, if (in a sense) it does, what is in that region is
presumably part of the brain, which would not be said to be in the
mind. When people say that sensible qualities are in the mind, they do
not mean "spatially contained in" in the sense in which the blackbirds
were in the pie. We might regard the mind as an assemblage of
particulars, namely, what would be called "states of mind," which
would belong together in virtue of some specific common quality. The
common quality of all states of mind would be the quality designated
by the word "mental"; and besides this we should have to suppose that
each separate person's states of mind have some common characteristic
distinguishing them from the states of mind of other people. Ignoring
this latter point, let us ask ourselves whether the quality designated
by the word "mental" does, as a matter of observation, actually belong
to objects of sense, such as colours or noises. I think any candid
person must reply that, however difficult it may be to know what we
mean by "mental," it is not difficult to see that colours and noises
are not mental in the sense of having that intrinsic peculiarity which
belongs to beliefs and wishes and volitions, but not to the physical
world. Berkeley advances on this subject a plausible argument[26]
which seems to me to rest upon an ambiguity in the word
"pain." He
argues that the realist supposes the heat which he feels in
approaching a fire to be something outside his mind, but that as he
approaches nearer and nearer to the fire the sensation of heat passes
imperceptibly into pain, and that no one could regard pain as
something outside the mind. In reply to this argument, it should be
observed in the first place that the heat of which we are immediately
aware is not in the fire but in our own body. It is only by inference
that the fire is judged to be the cause of the heat which we feel in
our body. In the second place (and this is the more important point),
when we speak of pain we may mean one of two things: we may mean the
object of the sensation or other experience which has the quality of
being painful, or we may mean the quality of painfulness itself. When
a man says he has a pain in his great toe, what he means is that he
has a sensation associated with his great toe and having the quality
of painfulness. The sensation itself, like every sensation, consists
in experiencing a sensible object, and the experiencing has that
quality of painfulness which only mental occurrences can have, but
which may belong to thoughts or desires, as well as to sensations. But
in common language we speak of the sensible object experienced in a
painful sensation as a pain, and it is this way of speaking which
causes the confusion upon which the plausibility of Berkeley's
argument depends. It would be absurd to attribute the quality of
painfulness to anything non-mental, and hence it comes to be thought
that what we call a pain in the toe must be mental. In fact, however,
it is not the sensible object in such a case which is painful, but the
sensation, that is to say, the experience of the sensible object. As
the heat which we experience from the fire grows greater, the
experience passes gradually from being pleasant to being painful, but
neither the pleasure nor the pain is a quality of the object
experienced as opposed to the experience, and it is therefore a
fallacy to argue that this object must be mental on the ground that
painfulness can only be attributed to what is mental.
If, then, when we say that something is in the mind we mean that it
has a certain recognisable intrinsic characteristic such as belongs to
thoughts and desires, it must be maintained on grounds of immediate
inspection that objects of sense are not in any mind.
A different meaning of "in the mind" is, however, to be inferred from
the arguments advanced by those who regard sensible objects as being
in the mind. The arguments used are, in the main, such as would prove
the causal dependence of objects of sense upon the percipient. Now
the notion of causal dependence is very obscure and difficult, much
more so in fact than is generally realised by philosophers. I shall
return to this point in a moment. For the present, however, accepting
the notion of causal dependence without criticism, I wish to urge that
the dependence in question is rather upon our bodies than upon our
minds. The visual appearance of an object is altered if we shut one
eye, or squint, or look previously at something dazzling; but all
these are bodily acts, and the alterations which they effect are to be
explained by physiology and optics, not by psychology.[27] They are in
fact of exactly the same kind as the alterations effected by
spectacles or a microscope. They belong therefore to the theory of the
physical world, and can have no bearing upon the question whether what
we see is causally dependent upon the mind. What they do tend to
prove, and what I for my part have no wish to deny, is that what we
see is causally dependent upon our body and is not, as crude common
sense would suppose, something which would exist equally if our eyes
and nerves and brain were absent, any more than the visual appearance
presented by an object seen through a microscope would remain if the
microscope were removed. So long as it is supposed that the physical
world is composed of stable and more or less permanent constituents,
the fact that what we see is changed by changes in our body appears to
afford reason for regarding what we see as not an ultimate constituent
of matter. But if it is recognised that the ultimate constituents of
matter are as circumscribed in duration as in spatial extent, the
whole of this difficulty vanishes.
There remains, however, another difficulty, connected with space. When
we look at the sun we wish to know something about the sun itself,
which is ninety-three million miles away; but what we see is dependent
upon our eyes, and it is difficult to suppose that our eyes can affect
what happens at a distance of ninety-three million miles. Physics
tells us that certain electromagnetic waves start from the sun, and
reach our eyes after about eight minutes. They there produce
disturbances in the rods and cones, thence in the optic nerve, thence
in the brain. At the end of this purely physical series, by some odd
miracle, comes the experience which we call "seeing the sun," and it
is such experiences which form the whole and sole reason for our
belief in the optic nerve, the rods and cones, the ninety-three
million miles, the electromagnetic waves, and the sun itself. It is
this curious oppositeness of direction between the order of causation
as affirmed by physics, and the order of evidence as revealed by
theory of knowledge, that causes the most serious perplexities in
regard to the nature of physical reality. Anything that invalidates
our seeing, as a source of knowledge concerning physical reality,
invalidates also the whole of physics and physiology.
And yet,
starting from a common-sense acceptance of our seeing, physics has
been led step by step to the construction of the causal chain in which
our seeing is the last link, and the immediate object which we see
cannot be regarded as that initial cause which we believe to be
ninety-three million miles away, and which we are inclined to regard
as the "real" sun.
I have stated this difficulty as forcibly as I can, because I believe
that it can only be answered by a radical analysis and reconstruction
of all the conceptions upon whose employment it depends.
Space, time, matter and cause, are the chief of these conceptions. Let
us begin with the conception of cause.
Causal dependence, as I observed a moment ago, is a conception which
it is very dangerous to accept at its face value. There exists a
notion that in regard to any event there is something which may be
called _the_ cause of that event--some one definite occurrence,