This physical reality is not, as psychical reality is, known to us directly; it is an interpretation of our sense experience. Immediate experience has objects, generally called sense data. These objects are what we actually see in sensations of sight, what we actually hear in sensations of sound, and so on; and they lead us to suppose or infer physical objects—that is, objects that do not depend upon our experience for their existence, but whose existence is the cause of our having the experience. The process by which we infer the nature of the external world from our felt experience is logical. It includes perceiving, conceiving, thinking or reasoning. The object of the logical process, the aim or ideal to which it seeks to attain, is truth. Knowledge of reality is truth.
There are therefore two realities, the reality of our felt experience from which all thinking sets out, and the reality which in thinking we seek to know. The one reality is immediate; it is conscious experience itself. The other reality is that which we infer from the fact of experience, that by which we seek to explain our existence. The one we feel, the other we think. If the difference between immediate knowledge and mediate knowledge or inference lay in the feeling of certainty alone or in the nature of belief, the distinction would not be the difficult one that it is. The theories of idealism and realism show how widely philosophers are divided on the subject. We are quite as certain of some of the things that we can only infer as we are of the things of which we are immediately aware. We cannot doubt, for instance, that there are other persons besides ourselves, yet we can have no distinct knowledge of any consciousness but one—our own. Our knowledge that there are other minds is an inference from our observation of the behaviour of some of the things we directly experience, and from the experience of our own consciousness. And even those things which seem in direct relation to us—the things we see, or hear, or touch—are immediately present in only a very small, perhaps an infinitesimal, part of what we know and think of as their full reality; all but this small part is inferred. From a momentary sensation of sight, or sound, or touch we infer reality that far exceeds anything actually given to us by the sensation.
Thinking is questioning experience. When our attention is suddenly attracted by something—a flash of light, or a sound, or a twinge of pain—consciously or unconsciously we say to ourself, What is that? The that—a simple felt experience—contains a meaning, brings a message, and we ask what? We distinguish the existence as an appearance, and we seek to know the reality. The quest of the reality which is made known to us by the appearance is the logical process of thought. The end or purpose of this logical process is to replace the immediate reality of the felt experience with a mediated-reality—that is, a reality made known to us. Directly, therefore, that we begin to think, the immediately present existence becomes an appearance, and throughout the development of our thought it is taken to be something that requires explanation. We seek to discover the reality which will explain it.
It is in this distinction of appearance and reality that the problem of truth arises. It does not depend upon any particular theory of knowledge. The same fact is recognised by idealists and by realists. Idealism may deny that the knowledge of independent reality is possible; realism may insist that it is implied in the very fact of consciousness itself—whichever is right, the reality which thinking brings before the mind is quite unlike and of a different order to that which we immediately experience in feeling. And even if we know nothing of philosophy, if we are ignorant of all theories of knowledge and think of the nature of knowledge simply from the standpoint of the natural man, the fact is essentially the same—the true reality of things is something concealed from outward view, something to be found out by science or by practical wisdom. Our knowledge of this reality may be true, in this case only is it knowledge; or it may be false, in which case it is not knowledge but opinion or error.
The reality then, the knowledge of which is truth, is not the immediate reality of feeling but the inferred reality of thought. To have any intelligible meaning, the affirmation that knowledge is true supposes that there already exists a distinction between knowledge and the reality known, between the being and the knowing of that which is known. In immediate knowledge, in actual conscious felt experience there is no such distinction, and therefore to affirm truth or error of such knowledge is unmeaning. I cannot have a toothache without knowing that I have it. In the actual felt toothache knowing and being are not only inseparable—they are indistinguishable. If, however, I think of my toothache as part of an independent order of reality, my knowledge of it may be true or false. I am then thinking of it as the effect of an exposed nerve, or of an abscess or of an inflammation—as something, that is to say, that is conditioned independently of my consciousness and that will cease to exist when the conditions are altered. In the same way, when I behold a landscape, the blue expanse of sky and variegated colour of the land which I actually experience are not either true or false, they are immediate experience in which knowing is being and being is knowing. Truth and error only apply to the interpretation of that experience, to the independent reality that I infer from it. We can, then, distinguish two kinds of knowledge which we may call immediate and mediate, or, better still, acquaintance and description. Accordingly, when we say that something is, or when we say of anything that it if real, we may mean either of two things. We may mean that it is part of the changing existence that we actually feel and that we call consciousness or life, or we may mean that it is part of an independent order of things whose existence we think about in order to explain, not what our feeling is (there can be no explanation of this), but how it comes to exist. We know by description a vast number of things with which we never can be actually acquainted. Such, indeed, is the case with all the knowledge by which we rule our lives and conceive the reality which environs us. Yet we are absolutely dependent on the reality we know by acquaintance for all our knowledge of these things. Not only is immediate sense experience and the knowledge it gives us by acquaintance the only evidence we have of the greater and wider reality, but we are dependent on it for the terms wherewith to describe it, for the form in which to present it, for the matter with which to compose it. And this is the real ground of the study of philosophy, the justification of its standpoint. It is this fact—this ultimate undeniable fact—that all reality of whatever kind and in whatever way known, whether by thought or by feeling, whether it is perceived or conceived, remembered or imagined, is in the end composed of sense experience: it is this fact from which all the problems of philosophy arise. It is this fact that our utilitarian men of science find themselves forced to recognise, however scornful they may be of metaphysical methods and results.
The special problem of the nature of truth is concerned, then, with the reality that we have distinguished as known by description, and conceived by us as independent in its existence of the consciousness by which we know it. What is the nature of the seal by which we stamp this knowledge true?
CHAPTER III
THE LOGICAL THEORIES
Whoever cares to become acquainted with the difficulty of the problem of truth must not be impatient of dialectical subtleties. There is a well-known story in Boswell's Life of Dr. Johnson which relates how the Doctor refuted Berkeley's philosophy which affirmed the non-existence of matter. "I observed," says Boswell, "that though we are satisfied his doctrine is not true, it is impossible to refute it. I shall never forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it—'I refute it thus.'" Dr. Johnson is the representative of robust common sense. It has very often turned out in metaphysical disputes that the common-sense answer is the one that has been justified in the end. Those who are impatient of metaphysics are, therefore, not without reasonable ground; and indeed the strong belief that the common-sense view will be justified in the end, however powerful the sceptical doubt that seems to contradict it, however startling the paradox that seems to be involved in it, is a possession of the human mind without which the ordinary practical conduct of life would be impossible. When, then, we ask ourselves, What is truth? the answer seems to be simple and obvious. Truth, we reply, is a property of certain of our ideas; it means their agreement, as falsity means their disagreement, with reality. If I say of anything that it is so, then, if it is so, what I say is true; if it is not so, then what I say is false. This simple definition of truth is one that is universally accepted. No one really can deny it, for if he did he would have nothing to appeal to to justify his own theory or condemn another. The problem of truth is only raised when we ask, What does the agreement of an idea with reality mean? If the reader will ask himself that question, and carefully ponder it, he will see that there is some difficulty in the answer to the simple question, What is truth? The answer that will probably first of all suggest itself is that the idea is a copy of the reality. And at once many experiences will seem to confirm this view. Thus when we look at a landscape we know that the lines of light which radiate from every point of it pass through the lens of each of our eyes to be focussed on the retina, forming there a small picture which is the exact counterpart of the reality. If we look into another person's eye we may see there a picture of the whole field of his vision reflected from his lens. It is true that what we see is not what he sees, for that is on his retina, but the analogy of this with a photographic camera, where we see the picture on the ground glass, seems obvious and natural; and so we think of knowledge, so far as it depends on the sense of vision, as consisting in more or less vivid, more or less faded, copies of real things stored up by the memory. But a very little reflection will convince us that the truth of our ideas cannot consist in the fact that they are copies of realities, for clearly they are not copies in any possible meaning of the term. Take, for example, this very illustration of seeing a landscape: what we see is not a picture or copy of the landscape, but the real landscape itself. We feel quite sure of this, and with regard to the other sensations, those that come to us by hearing, taste, smell, touch, it would seem highly absurd to suppose that the ideas these sensations produce in us are copies of real things. The pain of burning is not a copy of real fire, and the truth of the judgment, Fire burns, does not consist in the fact that the ideas denoted by the words "fire," "burns," faithfully copy certain real things which are not ideas. And the whole notion is seen to be absurd if we consider that, were it a fact that real things produce copies of themselves in our mind, we could never know it was so—all that we should have any knowledge of would be the copies, and whether these were like or unlike the reality, or indeed whether there was any reality for them to be like would, in the nature of the case, be unknowable, and we could never ask the question.
If, then, our ideas are not copies of things, and if there are things as well as ideas about things, it is quite clear that the ideas must correspond to the things in some way that does not make them copies of the things. The most familiar instance of correspondence is the symbolism we use in mathematics. Are our ideas of this nature? And is their truth their correspondence? Is a perfectly true idea one in which there exists a point to point correspondence to the reality it represents? At once there will occur to the mind a great number of instances where this seems to be the case. A map of England is not a copy of England such as, for example, a photograph might be if we were to imagine it taken from the moon. The correctness or the truth of a map consists in the correspondence between the reality and the diagram, which is an arbitrary sign of it. Throughout the whole of our ordinary life we find that we make use of symbols and signs that are not themselves either parts of or copies of the things for which they stand. Language itself is of this nature, and there may be symbols of symbols of symbols of real things. Written language is the arbitrary visual sign of spoken language, and spoken language is the arbitrary sign, it may be, of an experienced thing or of an abstract idea. Is, then, this property of our ideas which we call truth the correspondence of ideas with their objects, and is falsity the absence of this correspondence? It cannot be so. To imagine that ideas can correspond with realities is to forget that ideas simply are the knowledge of realities; it is to slip into the notion that we know two kinds of different things, first realities and secondly ideas, and that we can compare together these two sorts of things. But it is at once evident that if we could know realities without ideas, we should never need to have recourse to ideas. It is simply ridiculous to suppose that the relation between consciousness and reality which we call knowing is the discovery of a correspondence between mental ideas and real things. The two things that are related together in knowledge are not the idea and its object, but the mind and its object. The idea of the object is the knowledge of the object. There may be correspondence between ideas, but not between ideas and independent things, for that supposes that the mind knows the ideas and also knows the things and observes the correspondence between them. And even if we suppose that ideas are an independent kind of entity distinguishable and separable from another kind of entity that forms the real world, how could we know that the two corresponded, for the one would only be inferred from the other?