Books: The Problems of Philosophy

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In order to understand his argument, it is necessary to understand his
use of the word 'idea'. He gives the name 'idea' to anything which is
_immediately_ known, as, for example, sense-data are known. Thus a
particular colour which we see is an idea; so is a voice which we
hear, and so on. But the term is not wholly confined to sense-data.
There will also be things remembered or imagined, for with such things
also we have immediate acquaintance at the moment of remembering or
imagining. All such immediate data he calls 'ideas'.

He then proceeds to consider common objects, such as a tree, for
instance. He shows that all we know immediately when we 'perceive'
the tree consists of ideas in his sense of the word, and he argues
that there is not the slightest ground for supposing that there is
anything real about the tree except what is perceived. Its being, he
says, consists in being perceived: in the Latin of the schoolmen its
'_esse_' is '_percipi_'. He fully admits that the tree must continue
to exist even when we shut our eyes or when no human being is near it.
But this continued existence, he says, is due to the fact that God
continues to perceive it; the 'real' tree, which corresponds to what
we called the physical object, consists of ideas in the mind of God,
ideas more or less like those we have when we see the tree, but
differing in the fact that they are permanent in God's mind so long as
the tree continues to exist. All our perceptions, according to him,
consist in a partial participation in God's perceptions, and it is
because of this participation that different people see more or less
the same tree. Thus apart from minds and their ideas there is nothing
in the world, nor is it possible that anything else should ever be
known, since whatever is known is necessarily an idea.

There are in this argument a good many fallacies which have been
important in the history of philosophy, and which it will be as well
to bring to light. In the first place, there is a confusion
engendered by the use of the word 'idea'. We think of an idea as
essentially something in somebody's mind, and thus when we are told
that a tree consists entirely of ideas, it is natural to suppose that,
if so, the tree must be entirely in minds. But the notion of being
'in' the mind is ambiguous. We speak of bearing a person in mind, not
meaning that the person is in our minds, but that a thought of him is
in our minds. When a man says that some business he had to arrange
went clean out of his mind, he does not mean to imply that the
business itself was ever in his mind, but only that a thought of the
business was formerly in his mind, but afterwards ceased to be in his
mind. And so when Berkeley says that the tree must be in our minds if
we can know it, all that he really has a right to say is that a
thought of the tree must be in our minds. To argue that the tree
itself must be in our minds is like arguing that a person whom we bear
in mind is himself in our minds. This confusion may seem too gross to
have been really committed by any competent philosopher, but various
attendant circumstances rendered it possible. In order to see how it
was possible, we must go more deeply into the question as to the
nature of ideas.

Before taking up the general question of the nature of ideas, we must
disentangle two entirely separate questions which arise concerning
sense-data and physical objects. We saw that, for various reasons of
detail, Berkeley was right in treating the sense-data which constitute
our perception of the tree as more or less subjective, in the sense
that they depend upon us as much as upon the tree, and would not exist
if the tree were not being perceived. But this is an entirely
different point from the one by which Berkeley seeks to prove that
whatever can be immediately known must be in a mind. For this purpose
arguments of detail as to the dependence of sense-data upon us are
useless. It is necessary to prove, generally, that by being known,
things are shown to be mental. This is what Berkeley believes himself
to have done. It is this question, and not our previous question as
to the difference between sense-data and the physical object, that
must now concern us.

Taking the word 'idea' in Berkeley's sense, there are two quite
distinct things to be considered whenever an idea is before the mind.
There is on the one hand the thing of which we are aware--say the
colour of my table--and on the other hand the actual awareness itself,
the mental act of apprehending the thing. The mental act is
undoubtedly mental, but is there any reason to suppose that the thing
apprehended is in any sense mental? Our previous arguments concerning
the colour did not prove it to be mental; they only proved that its
existence depends upon the relation of our sense organs to the
physical object--in our case, the table. That is to say, they proved
that a certain colour will exist, in a certain light, if a normal eye
is placed at a certain point relatively to the table. They did not
prove that the colour is in the mind of the percipient.

Berkeley's view, that obviously the colour must be in the mind, seems
to depend for its plausibility upon confusing the thing apprehended
with the act of apprehension. Either of these might be called an
'idea'; probably either would have been called an idea by Berkeley.
The act is undoubtedly in the mind; hence, when we are thinking of the
act, we readily assent to the view that ideas must be in the mind.
Then, forgetting that this was only true when ideas were taken as acts
of apprehension, we transfer the proposition that 'ideas are in the
mind' to ideas in the other sense, i.e. to the things apprehended by
our acts of apprehension. Thus, by an unconscious equivocation, we
arrive at the conclusion that whatever we can apprehend must be in our
minds. This seems to be the true analysis of Berkeley's argument, and
the ultimate fallacy upon which it rests.

This question of the distinction between act and object in our
apprehending of things is vitally important, since our whole power of
acquiring knowledge is bound up with it. The faculty of being
acquainted with things other than itself is the main characteristic of
a mind. Acquaintance with objects essentially consists in a relation
between the mind and something other than the mind; it is this that
constitutes the mind's power of knowing things. If we say that the
things known must be in the mind, we are either unduly limiting the
mind's power of knowing, or we are uttering a mere tautology. We are
uttering a mere tautology if we mean by '_in_ the mind' the same as by
'_before_ the mind', i.e. if we mean merely being apprehended by the
mind. But if we mean this, we shall have to admit that what, _in this
sense_, is in the mind, may nevertheless be not mental. Thus when we
realize the nature of knowledge, Berkeley's argument is seen to be
wrong in substance as well as in form, and his grounds for supposing
that 'ideas'--i.e. the objects apprehended--must be mental, are found
to have no validity whatever. Hence his grounds in favour of idealism
may be dismissed. It remains to see whether there are any other
grounds.

It is often said, as though it were a self-evident truism, that we
cannot know that anything exists which we do not know. It is inferred
that whatever can in any way be relevant to our experience must be at
least capable of being known by us; whence it follows that if matter
were essentially something with which we could not become acquainted,
matter would be something which we could not know to exist, and which
could have for us no importance whatever. It is generally also
implied, for reasons which remain obscure, that what can have no
importance for us cannot be real, and that therefore matter, if it is
not composed of minds or of mental ideas, is impossible and a mere
chimaera.

To go into this argument fully at our present stage would be
impossible, since it raises points requiring a considerable
preliminary discussion; but certain reasons for rejecting the argument
may be noticed at once. To begin at the end: there is no reason why
what cannot have any _practical_ importance for us should not be real.
It is true that, if _theoretical_ importance is included, everything
real is of _some_ importance to us, since, as persons desirous of
knowing the truth about the universe, we have some interest in
everything that the universe contains. But if this sort of interest
is included, it is not the case that matter has no importance for us,
provided it exists even if we cannot know that it exists. We can,
obviously, suspect that it may exist, and wonder whether it does;
hence it is connected with our desire for knowledge, and has the
importance of either satisfying or thwarting this desire.

Again, it is by no means a truism, and is in fact false, that we
cannot know that anything exists which we do not know. The word
'know' is here used in two different senses. (1) In its first use it
is applicable to the sort of knowledge which is opposed to error, the
sense in which what we know is _true_, the sense which applies to our
beliefs and convictions, i.e. to what are called _judgements_. In
this sense of the word we know _that_ something is the case. This
sort of knowledge may be described as knowledge of _truths_. (2) In
the second use of the word 'know' above, the word applies to our
knowledge of _things_, which we may call _acquaintance_. This is the
sense in which we know sense-data. (The distinction involved is
roughly that between _savoir_ and _connaître_ in French, or between
_wissen_ and _kennen_ in German.)

Thus the statement which seemed like a truism becomes, when re-stated,
the following: 'We can never truly judge that something with which we
are not acquainted exists.' This is by no means a truism, but on the
contrary a palpable falsehood. I have not the honour to be acquainted
with the Emperor of China, but I truly judge that he exists. It may
be said, of course, that I judge this because of other people's
acquaintance with him. This, however, would be an irrelevant retort,
since, if the principle were true, I could not know that any one else
is acquainted with him. But further: there is no reason why I should
not know of the existence of something with which nobody is
acquainted. This point is important, and demands elucidation.

If I am acquainted with a thing which exists, my acquaintance gives me
the knowledge that it exists. But it is not true that, conversely,
whenever I can know that a thing of a certain sort exists, I or some
one else must be acquainted with the thing. What happens, in cases
where I have true judgement without acquaintance, is that the thing is
known to me by _description_, and that, in virtue of some general
principle, the existence of a thing answering to this description can
be inferred from the existence of something with which I am
acquainted. In order to understand this point fully, it will be well
first to deal with the difference between knowledge by acquaintance
and knowledge by description, and then to consider what knowledge of
general principles, if any, has the same kind of certainty as our
knowledge of the existence of our own experiences. These subjects
will be dealt with in the following chapters.

CHAPTER V
KNOWLEDGE BY ACQUAINTANCE AND KNOWLEDGE BY DESCRIPTION

In the preceding chapter we saw that there are two sorts of knowledge:
knowledge of things, and knowledge of truths. In this chapter we
shall be concerned exclusively with knowledge of things, of which in
turn we shall have to distinguish two kinds. Knowledge of things,
when it is of the kind we call knowledge by _acquaintance_, is
essentially simpler than any knowledge of truths, and logically
independent of knowledge of truths, though it would be rash to assume
that human beings ever, in fact, have acquaintance with things without
at the same time knowing some truth about them. Knowledge of things
by _description_, on the contrary, always involves, as we shall find
in the course of the present chapter, some knowledge of truths as its
source and ground. But first of all we must make clear what we mean
by 'acquaintance' and what we mean by 'description'.

We shall say that we have _acquaintance_ with anything of which we are
directly aware, without the intermediary of any process of inference
or any knowledge of truths. Thus in the presence of my table I am
acquainted with the sense-data that make up the appearance of my
table--its colour, shape, hardness, smoothness, etc.; all these are
things of which I am immediately conscious when I am seeing and
touching my table. The particular shade of colour that I am seeing
may have many things said about it--I may say that it is brown, that
it is rather dark, and so on. But such statements, though they make
me know truths about the colour, do not make me know the colour itself
any better than I did before so far as concerns knowledge of the
colour itself, as opposed to knowledge of truths about it, I know the
colour perfectly and completely when I see it, and no further
knowledge of it itself is even theoretically possible. Thus the
sense-data which make up the appearance of my table are things with
which I have acquaintance, things immediately known to me just as they
are.

My knowledge of the table as a physical object, on the contrary, is
not direct knowledge. Such as it is, it is obtained through
acquaintance with the sense-data that make up the appearance of the
table. We have seen that it is possible, without absurdity, to doubt
whether there is a table at all, whereas it is not possible to doubt
the sense-data. My knowledge of the table is of the kind which we
shall call 'knowledge by description'. The table is 'the physical
object which causes such-and-such sense-data'. This describes the
table by means of the sense-data. In order to know anything at all
about the table, we must know truths connecting it with things with
which we have acquaintance: we must know that 'such-and-such
sense-data are caused by a physical object'. There is no state of
mind in which we are directly aware of the table; all our knowledge of
the table is really knowledge of truths, and the actual thing which is
the table is not, strictly speaking, known to us at all. We know a
description, and we know that there is just one object to which this
description applies, though the object itself is not directly known to
us. In such a case, we say that our knowledge of the object is
knowledge by description.

All our knowledge, both knowledge of things and knowledge of truths,
rests upon acquaintance as its foundation. It is therefore important
to consider what kinds of things there are with which we have
acquaintance.

Sense-data, as we have already seen, are among the things with which
we are acquainted; in fact, they supply the most obvious and striking
example of knowledge by acquaintance. But if they were the sole
example, our knowledge would be very much more restricted than it is.
We should only know what is now present to our senses: we could not
know anything about the past--not even that there was a past--nor
could we know any truths about our sense-data, for all knowledge of
truths, as we shall show, demands acquaintance with things which are
of an essentially different character from sense-data, the things
which are sometimes called 'abstract ideas', but which we shall call
'universals'. We have therefore to consider acquaintance with other
things besides sense-data if we are to obtain any tolerably adequate
analysis of our knowledge.

The first extension beyond sense-data to be considered is acquaintance
by _memory_. It is obvious that we often remember what we have seen
or heard or had otherwise present to our senses, and that in such
cases we are still immediately aware of what we remember, in spite of
the fact that it appears as past and not as present. This immediate
knowledge by memory is the source of all our knowledge concerning the
past: without it, there could be no knowledge of the past by
inference, since we should never know that there was anything past to
be inferred.

The next extension to be considered is acquaintance by
_introspection_. We are not only aware of things, but we are often
aware of being aware of them. When I see the sun, I am often aware of
my seeing the sun; thus 'my seeing the sun' is an object with which I
have acquaintance. When I desire food, I may be aware of my desire
for food; thus 'my desiring food' is an object with which I am
acquainted. Similarly we may be aware of our feeling pleasure or
pain, and generally of the events which happen in our minds. This
kind of acquaintance, which may be called self-consciousness, is the
source of all our knowledge of mental things. It is obvious that it
is only what goes on in our own minds that can be thus known
immediately. What goes on in the minds of others is known to us
through our perception of their bodies, that is, through the
sense-data in us which are associated with their bodies. But for our
acquaintance with the contents of our own minds, we should be unable
to imagine the minds of others, and therefore we could never arrive at
the knowledge that they have minds. It seems natural to suppose that
self-consciousness is one of the things that distinguish men from
animals: animals, we may suppose, though they have acquaintance with
sense-data, never become aware of this acquaintance. I do not mean
that they _doubt_ whether they exist, but that they have never become
conscious of the fact that they have sensations and feelings, nor
therefore of the fact that they, the subjects of their sensations and
feelings, exist.

We have spoken of acquaintance with the contents of our minds as
_self_-consciousness, but it is not, of course, consciousness of our
_self_: it is consciousness of particular thoughts and feelings. The
question whether we are also acquainted with our bare selves, as
opposed to particular thoughts and feelings, is a very difficult one,
upon which it would be rash to speak positively. When we try to look
into ourselves we always seem to come upon some particular thought or
feeling, and not upon the 'I' which has the thought or feeling.
Nevertheless there are some reasons for thinking that we are
acquainted with the 'I', though the acquaintance is hard to
disentangle from other things. To make clear what sort of reason
there is, let us consider for a moment what our acquaintance with
particular thoughts really involves.

When I am acquainted with 'my seeing the sun', it seems plain that I
am acquainted with two different things in relation to each other. On
the one hand there is the sense-datum which represents the sun to me,
on the other hand there is that which sees this sense-datum. All
acquaintance, such as my acquaintance with the sense-datum which
represents the sun, seems obviously a relation between the person
acquainted and the object with which the person is acquainted. When a
case of acquaintance is one with which I can be acquainted (as I am
acquainted with my acquaintance with the sense-datum representing the
sun), it is plain that the person acquainted is myself. Thus, when I
am acquainted with my seeing the sun, the whole fact with which I am
acquainted is 'Self-acquainted-with-sense-datum'.

Further, we know the truth 'I am acquainted with this sense-datum'.
It is hard to see how we could know this truth, or even understand
what is meant by it, unless we were acquainted with something which we
call 'I'. It does not seem necessary to suppose that we are
acquainted with a more or less permanent person, the same to-day as
yesterday, but it does seem as though we must be acquainted with that
thing, whatever its nature, which sees the sun and has acquaintance
with sense-data. Thus, in some sense it would seem we must be
acquainted with our Selves as opposed to our particular experiences.
But the question is difficult, and complicated arguments can be
adduced on either side. Hence, although acquaintance with ourselves
seems _probably_ to occur, it is not wise to assert that it
undoubtedly does occur.

We may therefore sum up as follows what has been said concerning
acquaintance with things that exist. We have acquaintance in
sensation with the data of the outer senses, and in introspection with
the data of what may be called the inner sense--thoughts, feelings,
desires, etc.; we have acquaintance in memory with things which have
been data either of the outer senses or of the inner sense. Further,
it is probable, though not certain, that we have acquaintance with
Self, as that which is aware of things or has desires towards things.

In addition to our acquaintance with particular existing things, we
also have acquaintance with what we shall call _universals_, that is
to say, general ideas, such as _whiteness_, _diversity_,
_brotherhood_, and so on. Every complete sentence must contain at
least one word which stands for a universal, since all verbs have a
meaning which is universal. We shall return to universals later on,
in Chapter IX; for the present, it is only necessary to guard against
the supposition that whatever we can be acquainted with must be
something particular and existent. Awareness of universals is called
_conceiving_, and a universal of which we are aware is called a
_concept_.

It will be seen that among the objects with which we are acquainted
are not included physical objects (as opposed to sense-data), nor
other people's minds. These things are known to us by what I call
'knowledge by description', which we must now consider.

By a 'description' I mean any phrase of the form 'a so-and-so' or 'the
so-and-so'. A phrase of the form 'a so-and-so' I shall call an
'ambiguous' description; a phrase of the form 'the so-and-so' (in the
singular) I shall call a 'definite' description. Thus 'a man' is an
ambiguous description, and 'the man with the iron mask' is a definite
description. There are various problems connected with ambiguous
descriptions, but I pass them by, since they do not directly concern
the matter we are discussing, which is the nature of our knowledge
concerning objects in cases where we know that there is an object
answering to a definite description, though we are not acquainted with
any such object. This is a matter which is concerned exclusively with
definite descriptions. I shall therefore, in the sequel, speak simply
of 'descriptions' when I mean 'definite descriptions'. Thus a
description will mean any phrase of the form 'the so-and-so' in the
singular.

We shall say that an object is 'known by description' when we know
that it is 'the so-and-so', i.e. when we know that there is one
object, and no more, having a certain property; and it will generally
be implied that we do not have knowledge of the same object by
acquaintance. We know that the man with the iron mask existed, and
many propositions are known about him; but we do not know who he was.
We know that the candidate who gets the most votes will be elected,
and in this case we are very likely also acquainted (in the only sense
in which one can be acquainted with some one else) with the man who
is, in fact, the candidate who will get most votes; but we do not know
which of the candidates he is, i.e. we do not know any proposition of
the form 'A is the candidate who will get most votes' where A is one
of the candidates by name. We shall say that we have 'merely
descriptive knowledge' of the so-and-so when, although we know that
the so-and-so exists, and although we may possibly be acquainted with
the object which is, in fact, the so-and-so, yet we do not know any
proposition '_a_ is the so-and-so', where _a_ is something with which
we are acquainted.

When we say 'the so-and-so exists', we mean that there is just one
object which is the so-and-so. The proposition '_a_ is the so-and-so'
means that _a_ has the property so-and-so, and nothing else has. 'Mr.
A. is the Unionist candidate for this constituency' means 'Mr. A.
is a Unionist candidate for this constituency, and no one else is'.
'The Unionist candidate for this constituency exists' means 'some one
is a Unionist candidate for this constituency, and no one else is'.
Thus, when we are acquainted with an object which is the so-and-so, we
know that the so-and-so exists; but we may know that the so-and-so
exists when we are not acquainted with any object which we know to be
the so-and-so, and even when we are not acquainted with any object
which, in fact, is the so-and-so.

Common words, even proper names, are usually really descriptions.
That is to say, the thought in the mind of a person using a proper
name correctly can generally only be expressed explicitly if we
replace the proper name by a description. Moreover, the description
required to express the thought will vary for different people, or for
the same person at different times. The only thing constant (so long
as the name is rightly used) is the object to which the name applies.
But so long as this remains constant, the particular description
involved usually makes no difference to the truth or falsehood of the
proposition in which the name appears.

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