 The
Problems of Philosophy
Bertrand Russell
CHAPTER I
APPEARANCE AND REALITY
IS there any knowledge in the world which is so certain
that no reasonable man could doubt it? This question, which
at first sight might not seem difficult, is really one of
the most difficult that can be asked. When we have realized
the obstacles in the way of a straightforward and confident
answer, we shall be well launched on the study of philosophy
-- for philosophy is merely the attempt to answer such ultimate
questions, not carelessly and dogmatically, as we do in
ordinary life and even in the sciences, but critically after
exploring all that makes such questions puzzling, and after
realizing all the vagueness and confusion that underlie
our ordinary ideas.
In daily life, we assume as certain many things which,
on a closer scrutiny, are found to be so full of apparent
contradictions that only a great amount of thought enables
us to know what it is that we really may believe. In the
search for certainty, it is natural to begin with our present
experiences, and in some sense, no doubt, knowledge is to
be derived from them. But any statement as to what it is
that our immediate experiences make us know is very likely
to be wrong. It seems to me that I am now sitting in a chair,
at a table of a certain shape, on which I see sheets of
paper with writing or print. By turning my head I see out
of the window buildings and clouds and the sun. I believe
that the sun is about ninety-three million miles from the
earth; that it is a hot globe many times bigger than the
earth; that, owing to the earth's rotation, it rises every
morning, and will continue to do so for an indefinite time
in the future. I believe that, if any other normal person
comes into my room, he will see the same chairs and tables
and books and papers as I see, and that the table which
I see is the same as the table which I feel pressing against
my arm. All this seems to be so evident as to be hardly
worth stating, except in answer to a man who doubts whether
I know anything. Yet all this may be reasonably doubted,
and all of it requires much careful discussion before we
can be sure that we have stated it in a form that is wholly
true.
To make our difficulties plain, let us concentrate attention
on the table. To the eye it is oblong, brown and shiny,
to the touch it is smooth and cool and hard; when I tap
it, it gives out a wooden sound. Any one else who sees and
feels and hears the table will agree with this description,
so that it might seem as if no difficulty would arise; but
as soon as we try to be more precise our troubles begin.
Although I believe that the table is 'really' of the same
colour all over, the parts that reflect the light look much
brighter than the other parts, and some parts look white
because of reflected light. I know that, if I move, the
parts that reflect the light will be different, so that
the apparent distribution of colours on the table will change.
It follows that if several people are looking at the table
at the same moment, no two of them will see exactly the
same distribution of colours, because no two can see it
from exactly the same point of view, and any change in the
point of view makes some change in the way the light is
reflected.
For most practical purposes these differences are unimportant,
but to the painter they are all-important: the painter has
to unlearn the habit of thinking that things seem to have
the colour which common sense says they 'really' have, and
to learn the habit of seeing things as they appear. Here
we have already the beginning of one of the distinctions
that cause most trouble in philosophy -- the distinction
between 'appearance' and 'reality', between what things
seem to be and what they are. The painter wants to know
what things seem to be, the practical man and the philosopher
want to know what they are; but the philosopher's wish to
know this is stronger than the practical man's, and is more
troubled by knowledge as to the difficulties of answering
the question.
To return to the table. It is evident from what we have
found, that there is no colour which preeminently appears
to be the colour of the table, or even of any one
particular part of the table -- it appears to be of different
colours from different points of view, and there is no reason
for regarding some of these as more really its colour than
others. And we know that even from a given point of view
the colour will seem different by artificial light, or to
a colour-blind man, or to a man wearing blue spectacles,
while in the dark there will be no colour at all, though
to touch and hearing the table will be unchanged. This colour
is not something which is inherent in the table, but something
depending upon the table and the spectator and the way the
light falls on the table. When, in ordinary life, we speak
of the colour of the table, we only mean the sort
of colour which it will seem to have to a normal spectator
from an ordinary point of view under usual conditions of
light. But the other colours which appear under other conditions
have just as good a right to be considered real; and therefore,
to avoid favouritism, we are compelled to deny that, in
itself, the table has any one particular colour.
The same thing applies to the texture. With the naked eye
one can see the gram, but otherwise the table looks smooth
and even. If we looked at it through a microscope, we should
see roughnesses and hills and valleys, and all sorts of
differences that are imperceptible to the naked eye. Which
of these is the 'real' table? We are naturally tempted to
say that what we see through the microscope is more real,
but that in turn would be changed by a still more powerful
microscope. If, then, we cannot trust what we see with the
naked eye, why should we trust what we see through a microscope?
Thus, again, the confidence in our senses with which we
began deserts us.
The shape of the table is no better. We are all
in the habit of judging as to the 'real' shapes of things,
and we do this so unreflectingly that we come to think we
actually see the real shapes. But, in fact, as we all have
to learn if we try to draw, a given thing looks different
in shape from every different point of view. If our table
is 'really' rectangular, it will look, from almost all points
of view, as if it had two acute angles and two obtuse angles.
If opposite sides are parallel, they will look as if they
converged to a point away from the spectator; if they are
of equal length, they will look as if the nearer side were
longer. All these things are not commonly noticed in looking
at a table, because experience has taught us to construct
the 'real' shape from the apparent shape, and the 'real'
shape is what interests us as practical men. But the 'real'
shape is not what we see; it is something inferred from
what we see. And what we see is constantly changing in shape
as we, move about the room; so that here again the senses
seem not to give us the truth about the table itself, but
only about the appearance of the table.
Similar difficulties arise when we consider the sense of
touch. It is true that the table always gives us a sensation
of hardness, and we feel that it resists pressure. But the
sensation we obtain depends upon how hard we press the table
and also upon what part of the body we press with; thus
the various sensations due to various pressures or various
parts of the body cannot be supposed to reveal directly
any definite property of the table, but at most to be signs
of some property which perhaps causes all the sensations,
but is not actually apparent in any of them. And the same
applies still more obviously to the sounds which can be
elicited by rapping the table.
Thus it becomes evident that the real table, if there is
one, is not the same as what we immediately experience by
sight or touch or hearing. The real table, if there is one,
is not immediately known to us at all, but must
be an inference from what is immediately known. Hence, two
very difficult questions at once arise; namely, (1) Is there
a real table at all? (2) If so, what sort of object can
it be?
It will help us in considering these questions to have
a few simple terms of which the meaning is definite and
clear. Let us give the name of 'sense-data' to the things
that are immediately known in sensation: such things as
colours, sounds, smells, hardnesses, roughnesses, and so
on. We shall give the name 'sensation' to the experience
of being immediately aware of these things. Thus, whenever
we see a colour, we have a sensation of the colour,
but the colour itself is a sense-datum, not a sensation.
The colour is that of which we are immediately
aware, and the awareness itself is the sensation. It is
plain that if we are to know anything about the table, it
must be by means of the sense-data -- brown colour, oblong
shape, smoothness, etc. -- which we associate with the table;
but, for the reasons which have been given, we cannot say
that the table is the sense-data, or even that the sense-data
are directly properties of the table. Thus a problem arises
as to the relation of the sense-data to the real table,
supposing there is such a thing.
The real table, if it exists, we will call a 'physical
object'. Thus we have to consider the relation of sense-data
to physical objects. The collection of all physical objects
is called 'matter'. Thus our two questions may be re-stated
as follows: (1) Is there any such thing as matter? (2) If
so, what is its nature?
The philosopher who first brought prominently forward the
reasons for regarding the immediate objects of our senses
as not existing independently of us was Bishop Berkeley
(1685-1753). His Three Dialogues between Hylas and
Philonous, in Opposition to Sceptics and Atheists,
undertake to prove that there is no such thing as matter
at all, and that the world consists of nothing but minds
and their ideas. Hylas has hitherto believed in matter,
but he is no match for Philonous, who mercilessly drives
him into contradictions and paradoxes, and makes his own
denial of matter seem, in the end, as if it were almost
common sense. The arguments employed are of very different
value: some are important and sound, others are confused
or quibbling. But Berkeley retains the merit of having shown
that the existence of matter is capable of being denied
without absurdity, and that if there are any things that
exist independently of us they cannot be the immediate objects
of our sensations.
There are two different questions involved when we ask
whether matter exists, and it is important to keep them
clear. We commonly mean by 'matter' something which is opposed
to 'mind', something which we think of as occupying space
and as radically incapable of any sort of thought or consciousness.
It is chiefly in this sense that Berkeley denies matter;
that is to say, he does not deny that the sense-data which
we commonly take as signs of the existence of the table
are really signs of the existence of something
independent of us, but he does deny that this something
is nonmental, that it is neither mind nor ideas entertained
by some mind. He admits that there must be something which
continues to exist when we go out of the room or shut our
eyes, and that what we call seeing the table does really
give us reason for believing in something which persists
even when we are not seeing it. But he thinks that this
something cannot be radically different in nature from what
we see, and cannot be independent of seeing altogether,
though it must be independent of our seeing. He
is thus led to regard the 'real' table as an idea in the
mind of God. Such an idea has the required permanence and
independence of ourselves, without being -- as matter would
otherwise be -- something quite unknowable, in the sense
that we can only infer it, and can never be directly and
immediately aware of it.
Other philosophers since Berkeley have also held that,
although the table does not depend for its existence upon
being seen by me, it does depend upon being seen (or otherwise
apprehended in sensation) by some mind -- not necessarily
the mind of God, but more often the whole collective mind
of the universe. This they hold, as Berkeley does, chiefly
because they think there can be nothing real -- or at any
rate nothing known to be real except minds and their thoughts
and feelings. We might state the argument by which they
support their view in some such way as this: 'Whatever can
be thought of is an idea in the mind of the person thinking
of it; therefore nothing can be thought of except ideas
in minds; therefore anything else is inconceivable, and
what is inconceivable cannot exist.'
Such an argument, in my opinion, is fallacious; and of
course those who advance it do not put it so shortly or
so crudely. But whether valid or not, the argument has been
very widely advanced in one form or another; and very many
philosophers, perhaps a majority, have held that there is
nothing real except minds and their ideas. Such philosophers
are called 'idealists'. When they come to explaining matter,
they either say, like Berkeley, that matter is really nothing
but a collection of ideas, or they say, like Leibniz (1646-1716),
that what appears as matter is really a collection of more
or less rudimentary minds.
But these philosophers, though they deny matter as opposed
to mind, nevertheless, in another sense, admit matter. It
will be remembered that we asked two questions; namely,
(1) Is there a real table at all? (2) If so, what sort of
object can it be? Now both Berkeley and Leibniz admit that
there is a real table, but Berkeley says it is certain ideas
in the mind of God, and Leibniz says it is a colony of souls.
Thus both of them answer our first question in the affirmative,
and only diverge from the views of ordinary mortals in their
answer to our second question. In fact, almost all philosophers
seem to be agreed that there is a real table. they almost
all agree that, however much our sense-data -- colour, shape,
smoothness, etc. -- may depend upon us, yet their occurrence
is a sign of something existing independently of us, something
differing, perhaps, completely from our sense-data whenever
we are in a suitable relation to the real table.
Now obviously this point in which the philosophers are
agreed -- the view that there is a real table, whatever
its nature may be is vitally important, and it will be worth
while to consider what reasons there are for accepting this
view before we go on to the further question as to the nature
of the real table. Our next chapter, therefore, will be
concerned with the reasons for supposing that there is a
real table at all.
Before we go farther it will be well to consider for a
moment what it is that we have discovered so far. It has
appeared that, if we take any common object of the sort
that is supposed to be known by the senses, what the senses
immediately tell us is not the truth about the
object as it is apart from us, but only the truth about
certain sense-data which, so far as we can see, depend upon
the relations between us and the object. Thus what we directly
see and feel is merely 'appearance', which we believe to
be a sign of some 'reality' behind. But if the reality is
not what appears, have we any means of knowing whether there
is any reality at all? And if so, have we any means of finding
out what it is like?
Such questions are bewildering, and it is difficult to
know that even the strangest hypotheses may not be true.
Thus our familiar table, which has roused but the slightest
thoughts in us hitherto, has become a problem full of surprising
possibilities. The one thing we know about it is that it
is not what it seems. Beyond this modest result, so far,
we have the most complete liberty of conjecture. Leibniz
tells us it is a community of souls: Berkeley tells us it
is an idea in the mind of God; sober science, scarcely less
wonderful, tells us it is a vast collection of electric
charges in violent motion.
Among these surprising possibilities, doubt suggests that
perhaps there is no table at all. Philosophy, if it cannot
answer so many questions as we could wish, has at least
the power of asking questions which increase the interest
of the world, and show the strangeness and wonder lying
just below the surface even in the commonest things of daily
life.
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