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* E.g., “I was not drunk last night. I had only had two glasses; besides, it is well known that I am a teetotaller.”
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It is also urged that a thing that tastes sweet when I am well may taste bitter when I am ill. Very similar arguments are used about odours: since they are pleasant or unpleasant, “they cannot exist in any but a perceiving substance or mind.” Berkeley assumes, here and everywhere, that what does not inhere in matter must inhere in a mental substance, and that nothing can be both mental and material.
The argument in regard to sound is ad hominem. Hylas says that sounds are “really” motions in the air, and Philonous retorts that motions can be seen or felt, not heard, so that “real” sounds are unaudible. This is hardly a fair argument, since percepts of motion, according to Berkeley, are just as subjective as other percepts. The motions that Hylas requires will have to be unperceived and imperceptible. Nevertheless it is valid in so far as it points out that sound, as heard, cannot be identified with the motions of air that physics regards as its cause.
Hylas, after abandoning secondary qualities, is not yet ready to abandon primary qualities, viz. Extension, Figure, Solidity, Gravity, Motion, and Rest. The argument, naturally, concentrates on extension and motion. If things have real sizes, says Philonous, the same thing cannot be of different sizes at the same time, and yet it looks larger when we are near it than when we are far off. And if motion is really in the object, how comes it that the same motion may seem fast to one and slow to another? Such arguments must, I think, be allowed to prove the subjectivity of perceived space. But this subjectivity is physical: it is equally true of a camera, and therefore does not prove that shape is “mental.” In the second Dialogue Philonous sums up the discussion, so far as it has gone, in the words: “Besides spirits, all that we know or conceive are our own ideas.” He ought not, of course, to make an exception for spirits, since it is just as impossible to know spirit as to know matter. The arguments, in fact, are almost identical in both cases.
Let us now try to state what positive conclusions we can reach as a result of the kind of argument inaugurated by Berkeley.
Things as we know them are bundles of sensible qualities: a table, for example, consists of its visual shape, its hardness, the noise it emits when rapped, and its smell (if any). These different qualities have certain contiguities in experience, which lead common sense to regard them as belonging to one “thing,” but the concept of “thing” or “substance” adds nothing to the perceived qualities, and is unnecessary. So far we are on firm ground.
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But we must now ask ourselves what we mean by “perceiving.” Philonous maintains that, as regards sensible things, their reality consists in their being perceived; but he does not tell us what he means by perception. There is a theory, which he rejects, that perception is a relation between a subject and a percept. Since he believed the ego to be a substance, he might well have adopted this theory; however, he decided against it. For those who reject the notion of a substantial ego, this theory is impossible. What, then, is meant by calling something a “percept”? Does it mean anything more than that the something in question occurs? Can we turn Berkeley’s dictum round, and instead of saying that reality consists in being perceived, say that being perceived consists in being real? However this may be, Berkeley holds it logically possible that there should be unperceived things, since he holds that some real things, viz., spiritual substances, are unperceived. And it seems obvious that, when we say that an event is perceived, we mean something more than that it occurs.
What is this more? One obvious difference between perceived and unperceived events is that the former, but not the latter, can be remembered. Is there any other difference?
Recollection is one of a whole genus of effects which are more or less peculiar to the phenomena that we naturally call “mental.” These effects are connected with habit. A burnt child fears the fire; a burnt poker does not. The physiologist, however, deals with habit and kindred matters as a characteristic of nervous tissue, and has no need to depart from a physicalist interpretation. In physicalist language, we can say that an occurrence is “perceived” if it has effects of certain kinds; in this sense we might almost say that a watercourse “perceives” the rain by which it is deepened, and that a river valley is a “memory” of former downpours. Habit and memory, when described in physicalist terms, are not wholly absent in dead matter; the difference, in this respect, between living and dead matter, is only one of degree.
In this view, to say that an event is “perceived” is to say that it has effects of certain kinds, and there is no reason, either logical or empirical, for supposing that all events have effects of these kinds.
Theory of knowledge suggests a different standpoint. We start, here, not from finished science, but from whatever knowledge is the ground for our belief in science. This is what Berkeley is doing. Here it is not necessary, in advance, to define a “percept.” The method, in outline, is as follows. We collect the propositions that we feel we
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know without inference, and we find that most of these have to do with dated particular events. These events we define as “percepts.” Percepts, therefore, are those events that we know without inference; or at least, to allow for memory, such events were at some time percepts. We are then faced with the question: Can we, from our own percepts, infer any other events? Here four positions are possible, of which the first three are forms of idealism.
1. (1) We may deny totally the validity of all inferences from my present percepts and memories to other events. This view must be taken by any one who confines inference to deduction. Any event, and any group of events, is logically capable of standing alone, and therefore no group of events affords demonstrative proof of the existence of other events. If, therefore, we confine inference to deduction, the known world is confined to those events in our own biography that we perceive–or have perceived, if memory is admitted.
2. (2) The second position, which is solipsism as ordinarily understood, allows some inference from my percepts, but only to other events in my own biography. Take, for example, the view that, at any moment in waking life, there are sensible objects that we do not notice. We see many things without saying to ourselves that we see them; at least, so it seems. Keeping the eyes fixed in an environment in which we perceive no movement, we can notice various things in succession, and we feel persuaded that they were visible before we noticed them; but before we noticed them they were not data for theory of knowledge. This degree of inference from what we observe is made unreflectingly by everybody, even by those who most wish to avoid an undue extension of our knowledge beyond experience.
3. (3) The third position–which seems to be held, for instance, by Eddington–is that it is possible to make inferences to other events analogous to those in our own experience, and that, therefore, we have a right to believe that there are, for instance, colours seen by other people but not by ourselves, toothaches felt by other people, Pleasures enjoyed and pains endured by other people, and so on, but that we have no right to infer events experienced by no one and not forming part of any “mind.” This view may be defended on the ground that all inference to events which lie outside my observation is by analogy, and that events which no one experiences are not
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sufficiently analogous to my data to warrant analogical inferences.
5. (4) The fourth position is that of common sense and traditional physics, according to which there are, in addition to my own experiences and other people’s, also events which no one experiences–for example, the furniture of my bedroom when I am asleep and it is pitch dark. G. E. Moore once accused idealists of holding that trains only have wheels while they are in stations, on the ground that passengers cannot see the wheels while they remain in the train. Common sense refuses to believe that the wheels suddenly spring into being whenever you look, but do not bother to exist when no one is inspecting them. When this point of view is scientific, it bases the inference to unperceived events on causal laws.
I do not propose, at present, to decide between these four points of view. The decision, if possible at all, can only be made by an elaborate investigation of non-demonstrative inference and the theory of probability. What I do propose to do is to point out certain logical errors which have been committed by those who have discussed these questions.
Berkeley, as we have seen, thinks that there are logical reasons proving that only minds and mental events can exist. This view, on other grounds, is also held by Hegel and his followers. I believe this to be a complete mistake. Such a statement as “there was a time before life existed on this planet,” whether true or false, cannot be condemned
