IS THERE AN EXTERNAL WORLD?
12. HOW THE PLAIN MAN THINKS HE KNOWS THE WORLD.--As schoolboys we
enjoyed Cicero's joke at the expense of the "minute philosophers."
They denied the immortality of the soul; he affirmed it; and he
congratulated himself upon the fact that, if they were right, they
would not survive to discover it and to triumph over him.
At the close of the seventeenth century the philosopher John Locke was
guilty of a joke of somewhat the same kind. "I think," said he,
"nobody can, in earnest, be so skeptical as to be uncertain of the
existence of those things which he sees and feels. At least, he that
can doubt so far (whatever he may have with his own thoughts) will
never have any controversy with me; since he can never be sure I say
anything contrary to his own opinion."
Now, in this chapter and in certain chapters to follow, I am going to
take up and turn over, so that we may get a good look at them, some of
the problems that have presented themselves to those who have reflected
upon the world and the mind as they seem given in our experience. I
shall begin by asking whether it is not possible to doubt that there is
an external world at all.
The question cannot best be answered by a jest. It may, of course, be
absurd to maintain that there is no external world; but surely he, too,
is in an absurd position who maintains dogmatically that there is one,
and is yet quite unable to find any flaw in the reasonings of the man
who seems to be able to show that this belief has no solid foundation.
And we must not forget that the men who have thought it worth while to
raise just such questions as this, during the last twenty centuries,
have been among the most brilliant intellects of the race. We must not
assume too hastily that they have occupied themselves with mere
trivialities.
Since, therefore, so many thoughtful men have found it worth while to
ask themselves seriously whether there is an external world, or, at
least, how we can know that there is an external world, it is not
unreasonable to expect that, by looking for it, we may find in our
common experience or in science some difficulty sufficient to suggest
the doubt which at first strikes the average man as preposterous. In
what can such a doubt take its rise? Let us see.
I think it is scarcely too much to say that the plain man believes that
he _does not_ directly perceive an external world, and that he, at the
same time, believes that he _does_ directly perceive one. It is quite
possible to believe contradictory things, when one's thought of them is
somewhat vague, and when one does not consciously bring them together.
As to the first-mentioned belief. Does not the plain man distinguish
between his ideas of things and the things themselves? Does he not
believe that his ideas come to him through the avenues of the senses?
Is he not aware of the fact that, when a sense is disordered, the thing
as he perceives it is not like the thing "as it is"? A blind man does
not see things when they are there; a color-blind man sees them as
others do not see them; a man suffering under certain abnormal
conditions of the nervous system sees things when they are not there at
all, _i.e._ he has hallucinations. The thing itself, as it seems, is
not in the man's mind; it is the idea that is in the man's mind, and
that represents the thing. Sometimes it appears to give a true account
of it; sometimes it seems to give a garbled account; sometimes it is a
false representative throughout--there is no reality behind it. It is,
then, the _idea_ that is immediately known, and not the _thing_; the
thing is merely _inferred_ to exist.
I do not mean to say that the plain man is conscious of drawing this
conclusion. I only maintain that it seems a natural conclusion to draw
from the facts which he recognizes, and that sometimes he seems to draw
the conclusion half-consciously.
On the other hand, we must all admit that when the plain man is not
thinking about the distinction between ideas and things, but is looking
at some material object before him, is touching it with his fingers and
turning it about to get a good look at it, it never occurs to him that
he is not directly conscious of the thing itself.
He seems to himself to perceive the thing immediately; to perceive it
_as_ it is and _where_ it is; to perceive it as a really extended
thing, out there in space before his body. He does not think of
himself as occupied with mere images, representations of the object.
He may be willing to admit that his mind is in his head, but he cannot
think that what he sees is in his head. Is not the object _there_?
does he not _see_ and _feel_ it? Why doubt such evidence as this? He
who tells him that the external world does not exist seems to be
denying what is immediately given in his experience.
The man who looks at things in this way assumes, of course, that the
external object is known directly, and is not a something merely
inferred to exist from the presence of a representative image. May one
embrace this belief and abandon the other one? If we elect to do this,
we appear to be in difficulties at once. All the considerations which
made us distinguish so carefully between our ideas of things and the
things themselves crowd in upon us. Can it be that we know things
independently of the avenues of the senses? Would a man with different
senses know things just as we do? How can any man suffer from an
hallucination, if things are not inferred from images, but are known
independently?
The difficulties encountered appear sufficiently serious even if we
keep to that knowledge of things which seems to be given in common
experience. But even the plain man has heard of atoms and molecules;
and if he accepts the extension of knowledge offered him by the man of
science, he must admit that, whatever this apparently immediately
perceived external thing may be, it cannot be the external thing that
science assures him is out there in space beyond his body, and which
must be a very different sort of thing from the thing he seems to
perceive. The thing he perceives must, then, be _appearance_; and
where can that appearance be if not in his own mind?
The man who has made no study of philosophy at all does not usually
think these things out; but surely there are interrogation marks
written up all over his experience, and he misses them only because he
does not see clearly. By judiciously asking questions one may often
lead him either to affirm or to deny that he has an immediate knowledge
of the external world, pretty much as one pleases. If he affirms it,
his position does not seem to be a wholly satisfactory one, as we have
seen; and if he denies it, he makes the existence of the external world
wholly a matter of inference from the presence of ideas in the mind,
and he must stand ready to justify this inference.
To many men it has seemed that the inference is not an easy one to
justify. One may say: We could have no ideas of things, no sensations,
if real things did not exist and make an impression upon our senses.
But to this it may be answered: How is that statement to be proved? Is
it to be proved by observing that, when things are present and affect
the senses, there come into being ideas which represent the things?
Evidently such a proof as this is out of the question, for, if it is
true that we know external things only by inference and never
immediately, then we can never prove by observation that ideas and
things are thus connected. And if it is not to be proved by
observation, how shall it be proved? Shall we just assume it
dogmatically and pass on to something else? Surely there is enough in
the experience of the plain man to justify him in raising the question
whether he can certainly know that there is an external world.
13. THE PSYCHOLOGIST AND THE EXTERNAL WORLD.--We have seen just above
that the doubt regarding the existence of the world seems to have its
root in the familiar distinction between ideas and things, appearances
and the realities which they are supposed to represent. The
psychologist has much to say about ideas; and if sharpening and making
clear this distinction has anything to do with stirring up doubts, it
is natural to suppose that they should become more insistent when one
has exchanged the ignorance of everyday life for the knowledge of the
psychologist.
Now, when the psychologist asks how a given mind comes to have a
knowledge of any external thing, he finds his answer in the messages
which have been brought to the mind by means of the bodily senses. He
describes the sense-organs and the nervous connections between these
and the brain, and tells us that when certain nervous impulses have
traveled, let us say, from the eye or the ear to the brain, one has
sensations of sight or sound.
He describes for us in detail how, out of such sensations and the
memories of such sensations, we frame mental images of external things.
Between the mental image and the thing that it represents he
distinguishes sharply, and he informs us that the mind knows no more
about the external thing than is contained in such images. That a
thing is present can be known only by the fact that a message from the
thing is sent along the nerves, and what the thing is must be
determined from the character of the message. Given the image in the
absence of the thing,--that is to say, an hallucination,--the mind will
naturally suppose that the thing is present. This false supposition
cannot be corrected by a direct inspection of the thing, for such a
direct inspection of things is out of the question. The only way in
which the mind concerned can discover that the thing is absent is by
referring to its other experiences. This image is compared with other
images and is discovered to be in some way abnormal. We decide that it
is a false representative and has no corresponding reality behind it.
This doctrine taken as it stands seems to cut the mind off from the
external world very completely; and the most curious thing about it is
that it seems to be built up on the assumption that it is not really
true. How can one know certainly that there is a world of material
things, including human bodies with their sense-organs and nerves, if
no mind has ever been able to inspect directly anything of the sort?
How can we tell that a sensation arises when a nervous impulse has been
carried along a sensory nerve and has reached the brain, if every mind
is shut up to the charmed circle of its own ideas? The anatomist and
the physiologist give us very detailed accounts of the sense-organs and
of the brain; the physiologist even undertakes to measure the speed
with which the impulse passes along a nerve; the psychologist accepts
and uses the results of their labors. But can all this be done in the
absence of any first-hand knowledge of the things of which one is
talking? Remember that, if the psychologist is right, any external
object, eye, ear, nerve, or brain, which we can perceive directly, is a
mental complex, a something in the mind and not external at all. How
shall we prove that there are objects, ears, eyes, nerves, and
brains,--in short, all the requisite mechanism for the calling into
existence of sensations,--in an outer world which is not immediately
perceived but is only inferred to exist?
I do not wish to be regarded as impugning the right of the psychologist
to make the assumptions which he does, and to work as he does. He has
a right to assume, with the plain man, that there is an external world
and that we know it. But a very little reflection must make it
manifest that he seems, at least, to be guilty of an inconsistency, and
that he who wishes to think clearly should strive to see just where the
trouble lies.
So much, at least, is evident: the man who is inclined to doubt whether
there is, after all, any real external world, appears to find in the
psychologist's distinction between ideas and things something like an
excuse for his doubt. To get to the bottom of the matter and to
dissipate his doubt one has to go rather deeply into metaphysics. I
merely wish to show just here that the doubt is not a gratuitous one,
but is really suggested to the thoughtful mind by a reflection upon our
experience of things. And, as we are all apt to think that the man of
science is less given to busying himself with useless subtleties than
is the philosopher, I shall, before closing this chapter, present some
paragraphs upon the subject from the pen of a professor of mathematics
and mechanics.
14. THE "TELEPHONE EXCHANGE."--"We are accustomed to talk," writes
Professor Karl Pearson,[1] "of the 'external world,' of the 'reality'
outside us. We speak of individual objects having an existence
independent of our own. The store of past sense-impressions, our
thoughts and memories, although most probably they have beside their
psychical element a close correspondence with some physical change or
impress in the brain, are yet spoken of as _inside_ ourselves. On the
other hand, although if a sensory nerve be divided anywhere short of
the brain, we lose the corresponding class of sense impression, we yet
speak of many sense-impressions, such as form and texture, as existing
outside ourselves. How close then can we actually get to this supposed
world outside ourselves? Just as near but no nearer than the brain
terminals of the sensory nerves. We are like the clerk in the central
telephone exchange who cannot get nearer to his customers than his end
of the telephone wires. We are indeed worse off than the clerk, for to
carry out the analogy properly we must suppose him _never to have been
outside the telephone exchange, never to have seen a customer or any
one like a customer--in short, never, except through the telephone
wire, to have come in contact with the outside universe_. Of that
'real' universe outside himself he would be able to form no direct
impression; the real universe for him would be the aggregate of his
constructs from the messages which were caused by the telephone wires
in his office. About those messages and the ideas raised in his mind
by them he might reason and draw his inferences; and his conclusions
would be correct--for what? For the world of telephonic messages, for
the type of messages that go through the telephone. Something definite
and valuable he might know with regard to the spheres of action and of
thought of his telephonic subscribers, but outside those spheres he
could have no experience. Pent up in his office he could never have
seen or touched even a telephonic subscriber _in himself_. Very much
in the position of such a telephone clerk is the conscious _ego_ of
each one of us seated at the brain terminals of the sensory nerves.
Not a step nearer than those terminals can the _ego_ get to the 'outer
world,' and what in and for themselves are the subscribers to its nerve
exchange it has no means of ascertaining. Messages in the form of
sense-impressions come flowing in from that 'outside world,' and these
we analyze, classify, store up, and reason about. But of the nature of
'things-in-themselves,' of what may exist at the other end of our
system of telephone wires, we know nothing at all.
"But the reader, perhaps, remarks, 'I not only see an object, but I can
_touch_ it. I can trace the nerve from the tip of my finger to the
brain. I am not like the telephone clerk, I can follow my network of
wires to their terminals and find what is at the other end of them.'
Can you, reader? Think for a moment whether your _ego_ has for one
moment got away from his brain exchange. The sense-impression that you
call touch was just as much as sight felt only at the brain end of a
sensory nerve. What has told you also of the nerve from the tip of
your finger to your brain? Why, sense-impressions also, messages
conveyed along optic or tactile sensory nerves. In truth, all you have
been doing is to employ one subscriber to your telephone exchange to
tell you about the wire that goes to a second, but you are just as far
as ever from tracing out for yourself the telephone wires to the
individual subscriber and ascertaining what his nature is in and for
himself. The immediate sense-impression is just as far removed from
what you term the 'outside world' as the store of impresses. If our
telephone clerk had recorded by aid of a phonograph certain of the
messages from the outside world on past occasions, then if any
telephonic message on its receipt set several phonographs repeating
past messages, we have an image analogous to what goes on in the brain.
Both telephone and phonograph are equally removed from what the clerk
might call the 'real outside world,' but they enable him through their
sounds to construct a universe; he projects those sounds, which are
really inside his office, outside his office, and speaks of them as the
external universe. This outside world is constructed by him from the
contents of the inside sounds, which differ as widely from
things-in-themselves as language, the symbol, must always differ from
the thing it symbolizes. For our telephone clerk sounds would be the
real world, and yet we can see how conditioned and limited it would be
by the range of his particular telephone subscribers and by the
contents of their messages.
"So it is with our brain; the sounds from telephone and phonograph
correspond to immediate and stored sense-impressions. These
sense-impressions we project as it were outwards and term the real
world outside ourselves. But the things-in-themselves which the
sense-impressions symbolize, the 'reality,' as the metaphysicians wish
to call it, at the other end of the nerve, remains unknown and is
unknowable. Reality of the external world lies for science and for us
in combinations of form and color and touch--sense-impressions as
widely divergent from the thing 'at the other end of the nerve' as the
sound of the telephone from the subscriber at the other end of the
wire. We are cribbed and confined in this world of sense-impressions
like the exchange clerk in his world of sounds, and not a step beyond
can we get. As his world is conditioned and limited by his particular
network of wires, so ours is conditioned by our nervous system, by our
organs of sense. Their peculiarities determine what is the nature of
the outside world which we construct. It is the similarity in the
organs of sense and in the perceptive faculty of all normal human
beings which makes the outside world the same, or _practically_ the
same, for them all. To return to the old analogy, it is as if two
telephone exchanges had very nearly identical groups of subscribers.
In this case a wire between the two exchanges would soon convince the
imprisoned clerks that they had something in common and peculiar to
themselves. That conviction corresponds in our comparison to the
recognition of other consciousness."
I suggest that this extract be read over carefully, not once but
several times, and that the reader try to make quite clear to himself
the position of the clerk in the telephone exchange, _i.e._ the
position of the mind in the body, as depicted by Professor Pearson,
before recourse is had to the criticisms of any one else. One cannot
find anywhere better material for critical philosophical reflection.
As has been seen, our author accepts without question, the
psychological doctrine that the mind is shut up within the circle of
the messages that are conducted to it along the sensory nerves, and
that it cannot directly perceive anything truly external. He carries
his doctrine out to the bitter end in the conclusion that, since we
have never had experience of anything beyond sense-impressions, and
have no ground for an inference to anything beyond, we must recognize
that the only external world of which we know anything is an external
world built up out of sense-impressions. It is, thus, in the mind, and
is not external at all; it is only "projected outwards," _thought of_
as though it were beyond us. Shall we leave the inconsistent position
of the plain man and of the psychologist and take our refuge in this
world of projected mental constructs?
Before the reader makes up his mind to do this, I beg him to consider
the following:--
(1) If the only external world of which we have a right to speak at all
is a construct in the mind or _ego_, we may certainly affirm that the
world is in the _ego_, but does it sound sensible to say that the _ego_
is somewhere in the world?
(2) If all external things are really inside the mind, and are only
"projected" outwards, of course our own bodies, sense-organs, nerves,
and brains, are really inside and are merely projected outwards. Now,
do the sense-impressions of which everything is to be constructed "come
flowing in" along these nerves that are really inside?
(3) Can we say, when a nerve lies entirely within the mind or _ego_,
that this same mind or _ego_ is nearer to one end of the nerve than it
is to the other? How shall we picture to ourselves "the conscious
_ego_ of each one of us seated at the brain terminals of the sensory
nerves"? How can the _ego_ place the whole of itself at the end of a
nerve which it has constructed within itself? And why is it more
difficult for it to get to one end of a nerve like this than it is to
get to the other?
(4) Why should the thing "at the other end of the nerve" remain unknown
and unknowable? Since the nerve is entirely in the mind, is purely a
mental construct, can anything whatever be at the end of it without
being in the mind? And if the thing in question is not in the mind,
how are we going to prove that it is any nearer to one end of a nerve
which is inside the mind than it is to the other? If it may really be
said to be at the end of the nerve, why may we not know it quite as
well as we do the end of the nerve, or any other mental construct?
It must be clear to the careful reader of Professor Pearson's
paragraphs, that he does not confine himself strictly to the world of
mere "projections," to an outer world which is really _inner_. If he
did this, the distinction between inner and outer would disappear. Let
us consider for a moment the imprisoned clerk. He is in a telephone
exchange, about him are wires and subscribers. He gets only sounds and
must build up his whole universe of things out of sounds. Now we are
supposing him to be in a telephone exchange, to be receiving messages,
to be building up a world out of these messages. Do we for a moment
think of him as building up, out of the messages which came along the
wires, those identical wires which carried the messages and the
subscribers which sent them? Never! we distinguish between the
exchange, with its wires and subscribers, and the messages received and
worked up into a world. In picturing to ourselves the telephone
exchange, we are doing what the plain man and the psychologist do when
they distinguish between mind and body,--they never suppose that the
messages which come through the senses are identical with the senses
through which they come.
But suppose we maintain that there is no such thing as a telephone
exchange, with its wires and subscribers, which is not to be found
within some clerk. Suppose the real external world is something
_inner_ and only "projected" without, mistakenly supposed by the
unthinking to be without. Suppose it is nonsense to speak of a wire
which is not in the mind of a clerk. May we under such circumstances
describe any clerk as _in a telephone exchange_? as _receiving
messages_? as _no nearer_ to his subscribers than his end of the wire?
May we say that sense-impressions _come flowing in_ to him? The whole
figure of the telephone exchange becomes an absurdity when we have once
placed the exchange within the clerk. Nor can we think of two clerks
as connected by a wire, when it is affirmed that every wire must
"really" be in some clerk.
The truth is, that, in the extracts which I have given above and in
many other passages in the same volume, the real external world, the
world which does not exist in the mind but _without_ it, is much
discredited, and is yet not actually discarded. The ego is placed at
the brain terminals of the sensory nerves, and it receives messages
which _flow in_; _i.e._ the clerk is actually placed in an exchange.
That the existence of the exchange is afterward denied in so many words
does not mean that it has not played and does not continue to play an
important part in the thought of the author.
It is interesting to see how a man of science, whose reflections compel
him to deny the existence of the external world that we all seem to
perceive and that we somehow recognize as distinct from anything in our
minds, is _nevertheless compelled to admit the existence of this world
at every turn_.
But if we do admit it, what shall we make of it? Shall we deny the
truth of what the psychologist has to tell us about a knowledge of
things only through the sensations to which they give rise? We cannot,
surely, do that. Shall we affirm that we know the external world
directly, and at the same time that we do not know it directly, but
only indirectly, and through the images which arise in our minds? That
seems inconsistent. Certainly there is material for reflection here.
Nevertheless the more we reflect on that material, the more evident
does it become that the plain man cannot be wrong in believing in the
external world which seems revealed in his experiences. We find that
all attempts to discredit it rest upon the implicit assumption of its
existence, and fall to the ground when that existence is honestly
denied. So our problem changes its form. We no longer ask: Is there
an external world? but rather: _What_ is the external world, and how
does it differ from the world of mere ideas?
[1] "The Grammar of Science," 2d Ed., London, 1900, pp. 60-63.