The Project Gutenberg eBook, An Introduction to Philosophy, by George

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. 
 
 
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 Chap. III – Is There An External World? 
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. 
 
 
 
 
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 Chap. IV – Sensations and Things 
CHAPTER IV 
 
SENSATIONS AND “THINGS” 
 
15. SENSE AND IMAGINATION. – Every one distinguishes between things perceived and 
things only imagined.  With open eyes I see the desk before me; with eyes closed, I can imagine 
it.  I lay my hand on it and feel it; I can, without laying my hand on it, imagine that I feel it. I 
raise my eyes, and see the pictures on the wall opposite me; I can sit here and call before my 
mind the image of the door by which the house is entered. 
 
What is the difference between sense and imagination?  It must be a difference of which we are 
all somehow conscious, for we unhesitatingly distinguish between the things we perceive and the 
things we merely imagine. 
 
It is well to remember at the outset that the two classes of experiences are not wholly different.  
The blue color that I imagine seems blue.  It does not lose this quality because it is only 
imaginary.  The horse that I imagine seems to have four legs, like a horse perceived.  As I call it 
before my mind, it seems as large as the real horse.  Neither the color, nor the size, nor the 
distribution of parts, nor any other attribute of the sort appears to be different in the imaginary 
object from what it is in the object as given in sensation. 
 
The two experiences are, nevertheless, not the same; and every one knows that they are not the 
same.  One difference that roughly marks out the two classes of experiences from one another is 
that, as a rule, our sense-experiences are more vivid than are the images that exist in the 
imagination. 
 
I say, as a rule, for we cannot always remark this difference. Sensations may be very clear and 
unmistakable, but they may also be very faint and indefinite.  When a man lays his hand firmly 
on my shoulder, I may be in little doubt whether I feel a sensation or do not; but when he touches 
my back very lightly, I may easily be in doubt, and may ask myself in perplexity whether I have 
really been touched or whether I have merely imagined it.  As a vessel recedes and becomes a 
mere speck upon the horizon, I may well wonder, before I feel sure that it is really quite out of 
sight, whether I still see the dim little point, or whether I merely imagine that I see it. 
 
On the other hand, things merely imagined may sometimes be very vivid and insistent.  To some 
persons, what exists in the imagination is dim and indefinite in the extreme.  Others imagine 
things vividly, and can describe what is present only to the imagination almost as though it were 
something seen.  Finally, we know that an image may become so vivid and insistent as to be 
mistaken for an external thing.  That is to say, there are such things as hallucinations. 
 
The criterion of vividness will not, therefore, always serve to distinguish between what is given 
in the sense and what is only imagined.  And, indeed, it becomes evident, upon reflection, that 
we do not actually make it our ultimate test.  We may be quite willing to admit that faint 
sensations may come to be confused with what is imagined, with “ideas,” but we always regard 
such a confusion as somebody’s error.  We are not ready to admit that things perceived faintly 
are things imagined, or that vivid “ideas” are things perceived by sense. 
 
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 Chap. IV – Sensations and Things 
 
Let us come back to the illustrations with which we started.  How do I know that I perceive the 
desk before me; and how do I know that, sitting here, I imagine, and do not see, the front door of 
the house? 
 
My criterion is this: when I have the experience I call “seeing my desk,” the bit of experience 
which presents itself as my desk is in a certain setting.  That is to say, the desk seen must be in a 
certain relation to my body, and this body, as I know it, also consists of experiences.  Thus, if I 
am to know that I see the desk, I must realize that my eyes are open, that the object is in front of 
me and not behind me, etc. 
 
The desk as seen varies with the relation to the body in certain ways that we regard as natural 
and explicable.  When I am near it, the visual experience is not just what it is when I recede from 
it.  But how can I know that I am near the desk or far from it?  What do these expressions mean?  
Their full meaning will become clearer in the next chapter, but here I may say that nearness and 
remoteness must be measured for me in experiences of some sort, or I would never know 
anything as near to or far from my body. 
 
Thus, all our sensory experiences are experiences that fall into a certain system or order.  It is a 
system which we all recognize implicitly, for we all reject as merely imaginary those experiences 
which lack this setting.  If my eyes are shut – I am speaking now of the eyes as experienced, as 
felt or perceived, as given in sensation – I never say; “I see my desk,” no matter how vivid the 
image of the object.  Those who believe in “second sight” sometimes talk of seeing things not in 
this setting, but the very name they give to the supposed experience indicates that there is 
something abnormal about it.  No one thinks it remarkable that I see the desk before which I 
perceive myself to be sitting with open eyes.  Every one would think it strange if I could see and 
describe the table in the next room, now shut away from me.  When a man thinks he hears his 
name pronounced, and, turning his head, seeks in vain for the speaker, he sets his experience 
down as a hallucination.  He says, I did not really hear that; I merely imagined it. 
 
May one not, with open eyes, have a hallucination of vision, just as one may seem to hear one’s 
name pronounced when no one is by? Certainly.  But in each case the experience may be proved 
to be a hallucination, nevertheless.  It may be recognized that the sensory setting is incomplete, 
though it may not, at first, seem so.  Thus the unreal object which seems to be seen may be found 
to be a thing that cannot be touched.  Or, when one has attained to a relatively complete 
knowledge of the system of experiences recognized as sensory, one may make use of roundabout 
methods of ascertaining that the experience in question does not really have the right setting.  
Thus, the ghost which is seen by the terrified peasant at midnight, but which cannot be 
photographed, we may unhesitatingly set down as something imagined and not really seen. 
 
All our sensations are, therefore, experiences which take their place in a certain setting.  This is 
our ultimate criterion.  We need not take the word of the philosopher for it.  We need only 
reflect, and ask ourselves how we know that, in a given case, we are seeing or hearing or 
touching something, and are not merely imagining it.  In every case, we shall find that we come 
back to the same test.  In common life, we apply the test instinctively, and with little realization 
of what we are doing. 
 
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 Chap. IV – Sensations and Things 
 
And if we turn to the psychologist, whose business it is to be more exact and scientific, we find 
that he gives us only a refinement of this same criterion.  It is important to him to distinguish 
between what is given in sensation and what is furnished by memory or imagination, and he tells 
us that sensation is the result of a message conducted along a sensory nerve to the brain. 
 
Here we see emphasized the relation to the body which has been mentioned above.  If we ask the 
psychologist how he knows that the body he is talking about is a real body, and not merely an 
imagined one, he has to fall back upon the test which is common to us all.  A real hand is one 
which we see with the eyes open, and which we touch with the other hand.  If our experiences of 
our own body had not the setting which marks all sensory experiences, we could never say: I