russell.txt
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Title: The Problems of Philosophy
Author: Bertrand Russell
Release Date: June, 2004 [EBook #5827]
Posting Date: May 2, 2009
Language: English
Character set encoding: ASCII
*** START OF THIS PROJECT GUTENBERG EBOOK THE PROBLEMS OF PHILOSOPHY ***
Produced by Gordon Keener
THE PROBLEMS OF PHILOSOPHY
By Bertrand Russell
PREFACE
In the following pages I have confined myself in the main to those
problems of philosophy in regard to which I thought it possible to say
something positive and constructive, since merely negative criticism
seemed out of place. For this reason, theory of knowledge occupies a
larger space than metaphysics in the present volume, and some topics
much discussed by philosophers are treated very briefly, if at all.
I have derived valuable assistance from unpublished writings of G. E.
Moore and J. M. Keynes: from the former, as regards the relations
of sense-data to physical objects, and from the latter as regards
probability and induction. I have also profited greatly by the
criticisms and suggestions of Professor Gilbert Murray.
1912
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 pre-eminently 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 grain, 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 me