The author proceeds to shew how this idea of a mere group of sensations, actual or contingent, becomes knit up with an idea of a permanent Something, lying, as it were, under these sensations, and causing them; this further enlargement of the complex idea taking place through the intimate, or, as he calls it, inseparable association, generated by experience, which makes us unable to imagine any phenomenon as beginning to exist without something anterior to it which causes it. This explanation, seems to me quite correct as far as it goes; but, while it accounts for the difficulty we have in not ascribing our sensations to some cause or other, it does not explain why we accept, as in fact we do, the group itself as the cause. I have endeavoured to clear up this difficulty elsewhere (Examination of Sir William Hamilton’s Philosophy), and in preference to going over the ground a second time, I subjoin, at the end of the volume, the [chapter] containing the explanation. That chapter supplies all that appears to me to be further necessary on the subject of belief in outward objects; which is thus shewn to be a case of Conditional Expectation.
It is unnecessary to follow the author into the minute consideration of Belief in the existence of objects not present since the explanation already given equally applies to them. My belief in the present existence of St. Paul’s is correctly set forth by the author as consisting of the following elements: I believe that I have seen St. Paul’s: I believe that I shall see St. Paul’s, when I am again in St. Paul’s Churchyard: I believe that I should see St. Paul’s, if I were in St. Paul’s Churchyard at this instant. All this, as he justly remarks, is Memory or Expectation. And this, or some part of this, is 417 the whole of what is in any case meant by belief in the real existence of an external object. The author adds, I also believe that if any creature whose senses are analogous to my own, is now in St. Paul’s Churchyard, it has the present sensation of that edifice. But this belief is not necessary to my belief in the continued existence of St. Paul’s. For that, it suffices that I believe I should myself see it. My belief that other creatures would do so, is part of my belief in the real existence of other creatures like myself; which is no more mysterious, than our belief in the real existence of any other objects some of whose properties rest not on direct sensation, but on inference.
Belief in past existences, when those existences have been perceived by ourselves, is Memory. When the past existences are inferred from evidence, the belief of them is not Memory, but a fact of the same nature as Expectation; being a belief that we should have had the sensations if we had been cotemporary with the objects, and had been in the local position necessary for receiving sensible impressions from them.
We now come to the case of Belief in testimony. But testimony is not itself an object of belief. The object of belief is what the testimony asserts. And so in the last of the author’s three cases, that of assent to a proposition. The object of belief, in both these cases, is an assertion. But an assertion is something asserted, and what is asserted must be a fact, similar to some of those of which we have already treated. According to the author, belief in an assertion is belief that two names are both of them names of the same thing: but this we have felt ourselves obliged to [discard], as an inadequate explanation of the import of any assertions, except those which are classed as merely verbal. Every assertion concerning Things, whether in concrete or in abstract language, is an assertion that some fact, or group of facts, has been, is, or may be expected to be, found, wherever a certain other fact, or group of facts, is found. Belief in this, is therefore either remembrance that we did have, or expectation that we shall have, or a belief of the same nature with expectation that in 418 some given circumstances we should have, or should have had, direct perception of a particular fact. Belief, therefore, is always a case either of Memory or of Expectation; including under the latter name conditional as well as positive expectation, and the state of mind similar to expectation which affects us in regard to what would have been a subject of expectation, if the conditions of its realization had still been possible.
It may be objected, that we may believe in the real existence of things which are not objects of sense at all. We may. But we cannot believe in the real existence of anything which we do not conceive as capable of acting in some way upon our own or some other being’s consciousness; though the state of consciousness it produces may not be called a sensation. The existence of a thing means, to us, merely its capacity of producing an impression of some sort upon some mind, that is, of producing some state of consciousness. The belief, therefore, in its existence, is still a conditional expectation of something which we should, under some supposed circumstances, be capable of feeling.
To resume: Belief, as I conceive, is more than an inseparable association, for inseparable associations do not always generate belief, nor does belief always require, as one of its conditions, an inseparable association: we can believe that to be true which we are capable of conceiving or representing to ourselves as false, and false what we are capable of representing to ourselves as true. The difference between belief and mere imagination, is the difference between recognising something as a reality in nature, and regarding it as a mere thought of our own. This is the difference which presents itself when Memory has to be distinguished from Imagination; and again when Expectation, whether positive or contingent (i.e. whether it be expectation that we shall, or only persuasion that in certain definable circumstances we should, have a certain experience) has to be distinguished from the mere mental conception of that experience.
III.
Let us examine, once more, whether the speculations in the text afford us any means of further analysing this difference.
419 The difference presents itself in its most elementary form in the distinction between a sensation and an idea. The author [admits] this distinction to be ultimate and primordial. “A sensation is different from an idea, only because it is felt to be different.” But, after having admitted that these two states or consciousness are distinguishable from each other in and by themselves, he adds, that they are also distinguishable by their accompaniments. “The accompaniments of a sensation are always generically different from those of an idea….. The accompaniments of a sensation, are all the simultaneous objects of sensation, together with all those which, to a certain extent, both preceded and followed it. The accompaniments of an idea are not the simultaneous objects of sensation, but other ideas; namely, the neighbouring facts, antecedent and consequent, of the mental train.” There can be no doubt that in those individual cases in which ideas and sensations might be confounded, namely, when an idea reaches or approaches the vivacity of a sensation, the indication here pointed out helps to assure us that what we are conscious of is, nevertheless, only an idea. When, for instance, we awake from a dream, and open our eyes to the outward world, what makes us so promptly recognise that this and not the other is the real world, is that we find its phenomena connected in the accustomed order of our objects of sensation. But though this circumstance enables us, in particular instances, to refer our impression more instantaneously to one or the other class, it cannot be by this that we distinguish ideas at first from sensations; for the criterion supposes the distinction to be already made. If we judge a sensation to be a sensation because its accompaniments are other sensations, and an idea to be an idea because its accompaniments are other ideas, we must already be able to distinguish those other sensations from those other ideas.
A similar remark is applicable to a criterion between sensations and ideas, incidentally laid down by Mr. Bain in the First Part of his systematic treatise. “A mere picture or idea remains the same whatever be our bodily position or 420 bodily exertions; the sensation that we call the actual is entirely at the mercy of our movements, shifting in every possible way according to the varieties of action that we go through.” (The Senses and the Intellect, 2nd ed. p. 381.) This test, like the author’s, may serve in cases of momentary doubt; but sensations in general must have been already distinguished from ideas, before we could have hit upon this criterion between them. If we had not already known the difference between a sensation and an idea, we never could have discovered that one of them is “at the mercy of our movements,” and that the other is not.