_ 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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End of CHAPTER XI - ON INTUITIVE KNOWLEDGE
[Bertrand Russell's essay: The Problems of Philosophy] _