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<h2> CHAPTER XI. ON INTUITIVE KNOWLEDGE </h2>
<p>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.</p>
<p>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.</p>
<p>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.</p>
<p>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'.</p>
<p>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.</p>
<p>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 <i>true</i>.
Thus whatever self-evident truths may be obtained from our senses must be
different from the sense-data from which they are obtained.</p>
<p>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 <i>existence</i>
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 <i>round</i>
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.</p>
<p>Another class of intuitive judgements, analogous to those of sense and yet
quite distinct from them, are judgements of <i>memory</i>. 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.</p>
<p>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.</p>
<p>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.</p>
<p>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.</p>
<p>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.</p>
<p>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.</p>
<p>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.</p>
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