 The
Problems of Philosophy
Bertrand Russell
CHAPTER XI
ON INTUITIVE KNOWLEDGE
THERE is a common impression that everything that we believe
ought to be capable of proof, or at least of being shown
to be highly probable. It is felt by many that a belief
for which no reason can be given is an unreasonable belief.
In the main, this view is just. Almost all our common beliefs
are either inferred, or capable of being inferred, from
other beliefs which may be regarded as giving the reason
for them. As a rule, the reason has been forgotten, or has
even never been consciously present to our minds. Few of
us ever ask ourselves, for example, what reason there is
to suppose the food we are just going to eat will not turn
out to be poison. Yet we feel, when challenged, that a perfectly
good reason could be found, even if we are not ready with
it at the moment. And in this belief we are usually justified.
But let us imagine some insistent Socrates, who, whatever
reason we give him, continues to demand a reason for the
reason. We must sooner or later, and probably before very
long, be driven to a point where we cannot find any further
reason, and where it becomes almost certain that no further
reason is even theoretically discoverable. Starting with
the common beliefs of daily life, we can be driven back
from point to point, until we come to some general principle,
or some instance of a general principle, which seems luminously
evident, and is not itself capable of being deduced from
anything more evident. In most questions of daily life,
such as whether our food is likely to be nourishing and
not poisonous, we shall be driven back to the inductive
principle, which we discussed in Chapter VI. But beyond
that, there seems to be no further regress. The principle
itself is constantly used in our reasoning, sometimes consciously,
sometimes unconsciously; but there is no reasoning which,
starting from some simpler self-evident principle, leads
us to the principle of induction as its conclusion. And
the same holds for other logical principles. Their truth
is evident to us, and we employ them in constructing demonstrations;
but they themselves, or at least some of them, are incapable
of demonstration.
Self-evidence, however, is not confined to those among
general principles which are incapable of proof. When a
certain number of logical principles have been admitted,
the rest can be deduced from them; but the propositions
deduced are often just as self-evident as those that were
assumed without proof. All arithmetic, moreover, can be
deduced from the general principles of logic, yet the simple
propositions of arithmetic, such as 'two and two are four',
are just as self-evident as the principles of logic.
It would seem, also, though this is more disputable, that
there are some self-evident ethical principles, such as
'we ought to pursue what is good'.
It should be observed that, in all cases of general principles,
particular instances, dealing with familiar things, are
more evident than the general principle. For example, the
law of contradiction states that nothing can both have a
certain property and not have it. This is evident as soon
as it is understood, but it is not so evident as that a
particular rose which we see cannot be both red and not
red. (It is of course possible that parts of the rose may
be red and parts not red, or that the rose may be of a shade
of pink which we hardly know whether to call red or not;
but in the former case it is plain that the rose as a whole
is not red, while in the latter case the answer is theoretically
definite as soon as we have decided on a precise definition
of 'red'.) It is usually through particular instances that
we come to be able to see the general principle. Only those
who are practised in dealing with abstractions can readily
grasp a general principle without the help of instances.
In addition to general principles, the other kind of self-evident
truths are those immediately derived from sensation. We
will call such truths 'truths of perception', and the judgements
expressing them we will call 'judgements of perception'.
But here a certain amount of care is required in getting
at the precise nature of the truths that are self-evident.
The actual sense-data are neither true nor false. A particular
patch of colour which I see, for example, simply exists:
it is not the sort of thing that is true or false. It is
true that there is such a patch, true that it has a certain
shape and degree of brightness, true that it is surrounded
by certain other colours. But the patch itself, like everything
else in the world of sense, is of a radically different
kind from the things that are true or false, and therefore
cannot properly be said to be true. Thus whatever
self-evident truths may be obtained from our senses must
be different from the sense-data from which they are obtained.
It would seem that there are two kinds of self-evident
truths of perception, though perhaps in the last analysis
the two kinds may coalesce. First, there is the kind which
simply asserts the existence of the sense-datum, without
in any way analysing it. We see a patch of red, and we judge
'there is such-and-such a patch of red', or more strictly
'there is that'; this is one kind of intuitive judgement
of perception. The other kind arises when the object of
sense is complex, and we subject it to some degree of analysis.
If, for instance, we see a round patch of red, we may judge
'that patch of red is round'. This is again a judgement
of perception, but it differs from our previous kind. In
our present kind we have a single sense-datum which has
both colour and shape: the colour is red and the shape is
round. Our judgement analyses the datum into colour and
shape, and then recombines them by stating that the red
colour is round in shape. Another example of this kind of
judgement is 'this is to the right of that', where 'this'
and 'that' are seen simultaneously. In this kind of judgement
the sense-datum contains constituents which have some relation
to each other, and the judgement asserts that these constituents
have this relation.
Another class of intuitive judgements, analogous to those
of sense and yet quite distinct from them, are judgements
of memory. There is some danger of confusion as
to the nature of memory, owing to the fact that memory of
an object is apt to be accompanied by an image of the object,
and yet the image cannot be what constitutes memory. This
is easily seen by merely noticing that the image is in the
present, whereas what is remembered is known to be in the
past. Moreover, we are certainly able to some extent to
compare our image with the object remembered, so that we
often know, within somewhat wide limits, how far our image
is accurate; but this would be impossible, unless the object,
as opposed to the image, were in some way before the mind.
Thus the essence of memory is not constituted by the image,
but by having immediately before the mind an object which
is recognized as past. But for the fact of memory in this
sense, we should not know that there ever was a past at
all, nor should we be able to understand the word 'past',
any more than a man born blind can understand the word 'light'.
Thus there must be intuitive judgements of memory, and it
is upon them, ultimately, that all our knowledge of the
past depends.
The case of memory, however, raises a difficulty, for it
is notoriously fallacious, and thus throws doubt on the
trustworthiness of intuitive judgements in general. This
difficulty is no light one. But let us first narrow its
scope as far as possible. Broadly speaking, memory is trustworthy
in proportion to the vividness of the experience and to
its nearness in time. If the house next door was struck
by lightning half a minute ago, my memory of what I saw
and heard will be so reliable that it would be preposterous
to doubt whether there had been a flash at all. And the
same applies to less vivid experiences, so long as they
are recent. I am absolutely certain that half a minute ago
I was sitting in the same chair in which I am sitting now.
Going backward over the day, I find things of which I am
quite certain, other things of which I am almost certain,
other things of which I can become certain by thought and
by calling up attendant circumstances, and some things of
which I am by no means certain. I am quite certain that
I ate my breakfast this morning, but if I were as indifferent
to my breakfast as a philosopher should be, I should be
doubtful. As to the conversation at breakfast, I can recall
some of it easily, some with an effort, some only with a
large element of doubt, and some not at all. Thus there
is a continual gradation in the degree of self-evidence
of what I remember, and a corresponding gradation in the
trustworthiness of my memory.
Thus the first answer to the difficulty of fallacious memory
is to say that memory has degrees of self-evidence, and
that these correspond to the degrees of its trustworthiness,
reaching a limit of perfect self-evidence and perfect trustworthiness
in our memory of events which are recent and vivid.
It would seem, however, that there are cases of very firm
belief in a memory which is wholly false. It is probable
that, in these cases, what is really remembered, in the
sense of being immediately before the mind, is something
other than what is falsely believed in, though something
generally associated with it. George IV is said to have
at last believed that he was at the battle of Waterloo,
because he had so often said that he was. In this case,
what was immediately remembered was his repeated assertion;
the belief in what he was asserting (if it existed) would
be produced by association with the remembered assertion,
and would therefore not be a genuine case of memory. It
would seem that cases of fallacious memory can probably
all be dealt with in this way, i.e. they can be shown to
be not cases of memory in the strict sense at all.
One important point about self-evidence is made clear by
the case of memory, and that is, that self-evidence has
degrees: it is not a quality which is simply present or
absent, but a quality which may be more or less present,
in gradations ranging from absolute certainty down to an
almost imperceptible faintness. Truths of perception and
some of the principles of logic have the very highest degree
of self-evidence; truths of immediate memory have an almost
equally high degree. The inductive principle has less self-evidence
than some of the other principles of logic, such as 'what
follows from a true premiss must be true'. Memories have
a diminishing self-evidence as they become remoter and fainter;
the truths of logic and mathematics have (broadly speaking)
less self-evidence as they become more complicated. Judgements
of intrinsic ethical or aesthetic value are apt to have
some self-evidence, but not much.
Degrees of self-evidence are important in the theory of
knowledge, since, if propositions may (as seems likely)
have some degree of self-evidence without being true, it
will not be necessary to abandon all connexion between self-evidence
and truth, but merely to say that, where there is a conflict,
the more self-evident proposition is to be retained and
the less self-evident rejected.
It seems, however, highly probable that two different notions
are combined in 'self-evidence' as above explained; that
one of them, which corresponds to the highest degree of
self-evidence, is really an infallible guarantee of truth,
while the other, which corresponds to all the other degrees,
does not give an infallible guarantee, but only a greater
or less presumption. This, however, is only a suggestion,
which we cannot as yet develop further. After we have dealt
with the nature of truth, we shall return to the subject
of self-evidence, in connexion with the distinction between
knowledge and error.
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