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.

People commonly think that everything we believe should be provable, or at least shown to be highly probable. Many feel that a belief is unreasonable if no reason can be given for it. For the most part, this view is right. Almost all our everyday beliefs are drawn from other beliefs, or could be. Those other beliefs may be seen as reasons for holding them. Usually, we have forgotten the reason, or have never even been consciously aware of it. For example, few of us ever ask why we expect the food we are about to eat not to be poisonous. Yet when challenged, we feel that we could find a perfectly good reason, even if none comes to mind immediately. And we are usually justified in believing we could find such a reason.

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.

But imagine a persistent Socrates who keeps asking for a reason for every reason we give him. Sooner or later, and probably quite soon, we must reach a point where we can give no further reason. At that point, it becomes almost certain that no further reason could be discovered, even in theory. We can start with the ordinary beliefs of daily life and be pushed back from one reason to another. Eventually, we reach a general principle, or an instance of one, that seems perfectly clear and self-evident. We cannot deduce that principle or instance from anything more evident. In most everyday questions, we will be pushed back to the principle of induction, discussed in Chapter VI. One example is whether our food is likely to nourish us rather than poison us. But beyond the principle of induction, there seems to be no further step back. We constantly use the principle in our reasoning, sometimes consciously and sometimes unconsciously. But no reasoning leads from a simpler, self-evident principle to the principle of induction as its conclusion. The same is true of other logical principles. Their truth is evident to us, and we use them to construct proofs. But these principles themselves, or at least some of them, cannot be proved.

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.

However, self-evidence is not limited to general principles that cannot be proved. Once certain logical principles are accepted, the rest can be deduced from them. But the deduced statements are often just as self-evident as the principles accepted without proof. Moreover, all arithmetic can be deduced from the general principles of logic. Yet simple statements of arithmetic, such as 'two and two are four', are just as self-evident as logical principles.

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 also seems that some ethical principles are self-evident, though this claim is more debatable. One example is '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.

For all general principles, specific examples involving familiar things are more obvious than the general principle itself. For example, the law of contradiction states that nothing can both have a certain property and lack that property. This law is obvious as soon as we understand it. But a particular rose we see even more obviously cannot be both red and not red. (Of course, parts of the rose may be red and other parts not red. Or the rose may be a shade of pink that we hardly know whether to call red or not. In the first case, the rose as a whole is clearly not red. In the second case, the answer is theoretically definite once we have settled on a precise definition of 'red'.) We usually come to understand a general principle through specific examples. Only people experienced in working with abstract ideas can readily grasp a general principle without examples.

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.

Besides general principles, the other kind of self-evident truths are those we get directly from sensation. We will call these 'truths of perception'. We will call the judgements that express these truths 'judgements of perception'. But we must take some care to identify exactly which truths are self-evident. The sense-data themselves are neither true nor false. For example, a particular patch of colour I see simply exists. The patch is not the sort of thing that can be true or false. It is true that such a patch exists. It is true that the patch has a certain shape and degree of brightness. It is true that certain other colours surround the patch. But the patch itself, like everything else we sense, is fundamentally different from things that are true or false. So the patch cannot properly be called true. Thus, whatever self-evident truths we may get from our senses must differ from the sense-data we get them from.

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.

There seem to be two kinds of self-evident truths of perception, though perhaps the two may ultimately merge. The first kind simply asserts the existence of a sense-datum, without analysing it in any way. We see a patch of red and judge 'there is such-and-such a patch of red', or more precisely 'there is that'. This is one kind of intuitive judgement of perception. The other kind arises when the object we perceive is complex and we analyse it to some degree. If, for instance, we see a round patch of red, we may judge 'that patch of red is round'. This is also a judgement of perception, but it differs from the first kind. Here we have a single sense-datum with both colour and shape: the colour is red and the shape is round. Our judgement analyses the sense-datum into colour and shape, then brings them together again. It does so 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'. Here, 'this' and 'that' are seen at the same time. In this kind of judgement, the sense-datum contains parts that have some relation to each other. The judgement asserts that these parts 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.

Another class of intuitive judgments concerns memory. These judgments resemble judgments of sense but are quite distinct from them. There is some risk of confusion about the nature of memory. Remembering an object often comes with an image of the object, yet the image cannot itself constitute memory. We can easily see why: the image exists in the present, while we know that what we remember belongs to the past. Moreover, we can certainly compare our image with the remembered object to some extent. So we often know, within fairly broad limits, how accurate our image is. But such comparison would be impossible unless the object itself, rather than the image, were somehow present to the mind. Thus, the essence of memory is not the image. Instead, memory consists in having an object immediately before the mind and recognizing the object as past. Without memory in this sense, we would not know that there had ever been a past at all. Nor could we understand the word 'past', any more than a man born blind can understand the word 'light'. So there must be intuitive judgments of memory. Ultimately, all our knowledge of the past depends on these judgments.

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.

Memory, however, presents a difficulty, because it is notoriously unreliable. Its unreliability casts doubt on intuitive judgments in general. This is a serious difficulty. But first, let us limit its scope as much as possible. Broadly speaking, memory becomes more reliable the more vivid and recent the experience is. Suppose the house next door was struck by lightning half a minute ago. My memory of what I saw and heard would be so reliable that doubting there was a flash would be absurd. The same applies to less vivid experiences, as long as they are recent. I am absolutely certain that half a minute ago I was sitting in the same chair I occupy now. Looking back over the day, I find some things I am quite certain about and others I am almost certain about. I can become certain about other things by thinking and recalling the surrounding circumstances. And there are some things I am not at all certain about. I am quite certain that I ate breakfast this morning. But if I were as indifferent to breakfast as a philosopher should be, I would be doubtful. As for the conversation at breakfast, I can recall some of it easily and some with an effort. Some I can recall only with considerable doubt, and some not at all. So the degree to which my memories are self-evident varies along a continuous scale. The reliability of my memory varies accordingly.

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.

So the first answer to the problem of faulty memory is that memories have different degrees of self-evidence. These degrees correspond to how trustworthy the memories are. Our memories of recent, vivid events reach the limit of perfect self-evidence and perfect trustworthiness.

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.

However, there seem to be cases where people firmly believe in a memory that is entirely false. In these cases, what is actually remembered is probably something other than what the person falsely believes. Here, what is remembered means what is directly present in the mind. Although different from the false belief, the remembered thing is generally associated with it. George IV is said to have eventually believed he was at the battle of Waterloo because he repeatedly said so. In his case, what he directly remembered was his repeated claim. His belief that he had been at Waterloo, if he held that belief, would have arisen through association with the remembered claim. So his belief would not be a genuine case of memory. It seems that all cases of false memory can probably be explained this way. That is, they can be shown not to be 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.

Memory makes one important point about self-evidence clear: self-evidence comes in degrees. It is not a quality that is simply present or absent. Instead, it ranges from absolute certainty to a faintness that is almost impossible to detect. Truths of perception and some principles of logic have the highest degree of self-evidence. Truths of immediate memory have an almost equally high degree. The inductive principle has less self-evidence than some other principles of logic, such as 'what follows from a true premiss must be true'. Memories become less self-evident as they grow more distant and fainter. Broadly speaking, truths of logic and mathematics become less self-evident as they grow more complicated. Judgments about intrinsic ethical or aesthetic value tend 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.

Degrees of self-evidence matter in the theory of knowledge. The reason is that statements may have some degree of self-evidence without being true, as seems likely. If so, we need not abandon all connection between self-evidence and truth. We need only say that, when statements conflict, we should keep the more self-evident statement and reject the less self-evident one.

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.

However, it seems highly probable that 'self-evidence', as explained above, combines two different ideas. One corresponds to the highest degree of self-evidence and truly provides an infallible guarantee of truth. The other corresponds to all the remaining degrees and offers no infallible guarantee, only stronger or weaker grounds for belief. However, this distinction is only a suggestion, and we cannot yet develop it further. After examining the nature of truth, we shall return to self-evidence in relation to the distinction between knowledge and error.