Language sometimes conceals the complexity of a belief. We say that a person believes in God, and it might seem as if God formed the whole content of the belief. But what is really believed is that God exists, which is very far from being simple. Similarly, when a person has a memory-image with a memory-belief, the belief is "this occurred," in the sense explained in Lecture IX; and "this occurred" is not simple. In like manner all cases where the content of a belief seems simple at first sight will be found, on examination, to confirm the view that the content is always complex.
The content of a belief involves not merely a plurality of constituents, but definite relations between them; it is not determinate when its constituents alone are given. For example, "Plato preceded Aristotle" and "Aristotle preceded Plato" are both contents which may be believed, but, although they consist of exactly the same constituents, they are different, and even incompatible.
The content of a belief may consist of words only, or of images only, or of a mixture of the two, or of either or both together with one or more sensations. It must contain at least one constituent which is a word or an image, and it may or may not contain one or more sensations as constituents. Some examples will make these various possibilities clear.
We may take first recognition, in either of the forms "this is of such-and-such a kind" or "this has occurred before." In either case, present sensation is a constituent. For example, you hear a noise, and you say to yourself "tram." Here the noise and the word "tram" are both constituents of your belief; there is also a relation between them, expressed by "is" in the proposition "that is a tram." As soon as your act of recognition is completed by the occurrence of the word "tram," your actions are affected: you hurry if you want the tram, or cease to hurry if you want a bus. In this case the content of your belief is a sensation (the noise) and a word ("tram") related in a way which may be called predication.
The same noise may bring into your mind the visual image of a tram, instead of the word "tram." In this case your belief consists of a sensation and an image suitable related. Beliefs of this class are what are called "judgments of perception." As we saw in Lecture VIII, the images associated with a sensation often come with such spontaneity and force that the unsophisticated do not distinguish them from the sensation; it is only the psychologist or the skilled observer who is aware of the large mnemic element that is added to sensation to make perception. It may be objected that what is added consists merely of images without belief. This is no doubt sometimes the case, but is certainly sometimes not the case. That belief always occurs in perception as opposed to sensation it is not necessary for us to maintain; it is enough for our purposes to note that it sometimes occurs, and that when it does, the content of our belief consists of a sensation and an image suitably related.
In a PURE memory-belief only images occur. But a mixture of words and images is very common in memory. You have an image of the past occurrence, and you say to yourself: "Yes, that's how it was." Here the image and the words together make up the content of the belief. And when the remembering of an incident has become a habit, it may be purely verbal, and the memory-belief may consist of words alone.
The more complicated forms of belief tend to consist only of words. Often images of various kinds accompany them, but they are apt to be irrelevant, and to form no part of what is actually believed. For example, in thinking of the Solar System, you are likely to have vague images of pictures you have seen of the earth surrounded by clouds, Saturn and his rings, the sun during an eclipse, and so on; but none of these form part of your belief that the planets revolve round the sun in elliptical orbits. The only images that form an actual part of such beliefs are, as a rule, images of words. And images of words, for the reasons considered in Lecture VIII, cannot be distinguished with any certainty from sensations, when, as is often, if not usually, the case, they are kinaesthetic images of pronouncing the words.
It is impossible for a belief to consist of sensations alone, except when, as in the case of words, the sensations have associations which make them signs possessed of meaning. The reason is that objective reference is of the essence of belief, and objective reference is derived from meaning. When I speak of a belief consisting partly of sensations and partly of words, I do not mean to deny that the words, when they are not mere images, are sensational, but that they occur as signs, not (so to speak) in their own right. To revert to the noise of the tram, when you hear it and say "tram," the noise and the word are both sensations (if you actually pronounce the word), but the noise is part of the fact which makes your belief true, whereas the word is not part of this fact. It is the MEANING of the word "tram," not the actual word, that forms part of the fact which is the objective of your belief. Thus the word occurs in the belief as a symbol, in virtue of its meaning, whereas the noise enters into both the belief and its objective. It is this that distinguishes the occurrence of words as symbols from the occurrence of sensations in their own right: the objective contains the sensations that occur in their own right, but contains only the meanings of the words that occur as symbols.
For the sake of simplicity, we may ignore the cases in which sensations in their own right form part of the content of a belief, and confine ourselves to images and words. We may also omit the cases in which both images and words occur in the content of a belief. Thus we become confined to two cases: (a) when the content consists wholly of images, (b) when it consists wholly of words. The case of mixed images and words has no special importance, and its omission will do no harm.
Let us take in illustration a case of memory. Suppose you are thinking of some familiar room. You may call up an image of it, and in your image the window may be to the left of the door. Without any intrusion of words, you may believe in the correctness of your image. You then have a belief, consisting wholly of images, which becomes, when put into words, "the window is to the left of the door." You may yourself use these words and proceed to believe them. You thus pass from an image-content to the corresponding word-content. The content is different in the two cases, but its objective reference is the same. This shows the relation of image-beliefs to word-beliefs in a very simple case. In more elaborate cases the relation becomes much less simple.