They now come to colours, and here Hylas begins confidently: “Pardon me: the case of colours is very different. Can anything be plainer than that we see them on the objects?” Substances existing without the mind, he maintains, have the colours we see on them. But Philonous has no difficulty in disposing of this view. He begins with the sunset clouds, which are red and golden, and points out that a cloud, when you are close to it, has no such colours. He goes on to the difference made by a microscope, and to the yellowness of everything to a man who has jaundice. And very small insects, he says, must be able to see much smaller objects than we can see. Hylas thereupon says that colour is not in the objects, but in the light; it is, he says, a thin fluid substance. Philonous points out, as in the case of sound, that, according to Hylas, “real” colours are something different from the red and blue that we see, and that this won’t do.
Hereupon Hylas gives way about all secondary qualities, but continues to say that primary qualities, notably figure and motion, are inherent in external unthinking substances. To this Philonous replies that things look big when we are near them and small when we are far off, and that a movement may seem quick to one man and slow to another.
At this point Hylas attempts a new departure. He made a mistake, he says, in not distinguishing the object from the sensation; the act of perceiving he admits to be mental, but not what is perceived; colours, for example, “have a real existence without the mind, in some unthinking substance.” To this Philonous replies: “That any immediate object of the senses–that is, any idea or combination of ideas–should exist in an unthinking substance, or exterior to all minds, is in itself an evi-
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dent contradiction.” It will be observed that, at this point, the argument becomes logical and is no longer empirical. A few pages later, Philonous says: “Whatever is immediately perceived is an idea; and can any idea exist out of the mind?”
After a metaphysical discussion of substance, Hylas returns to the discussion of visual sensations, with the argument that he sees things at a distance. To this Philonous replies that this is equally true of things seen in dreams, which every one admits to be mental; further, that distance is not perceived by sight, but judged as the result of experience, and that, to a man born blind but now for the first time able to see, visual objects would not appear distant.
At the beginning of the second Dialogue, Hylas urges that certain traces in the brain are the causes of sensations, but Philonous retorts that “the brain, being a sensible thing, exists only in the mind.”
The remainder of the Dialogues is less interesting, and need not be considered.
Let us now make a critical analysis of Berkeley’s contentions.
Berkeley’s argument consists of two parts. On the one hand, he argues that we do not perceive material things, but only colours, sounds, etc., and that these are “mental” or “in the mind.” His reasoning is completely cogent as to the first point, but as to the second it suffers from the absence of any definition of the word “mental.” He relics, in fact, upon the received view that everything must be either material or mental, and that nothing is both.
When he says that we perceive qualities, not “things” or “material substances,” and that there is no reason to suppose that the different qualities which common sense regards as all belonging to one “thing” inhere in a substance distinct from each and all of them, his reasoning may be accepted. But when he goes on to say that sensible qualities-including primary qualities–are “mental,” the arguments are of very different kinds, and of very different degrees of validity. There are some attempting to prove logical necessity, while others are more empirical. Let us take the former first.
Philonous says: “Whatever is immediately perceived is an idea: and can any idea exist out of the mind?” This would require a long discussion of the word “idea.” If it were held that thought and perception consist of a relation between subject and object, it would be possible to identify the mind with the subject, and to maintain that there is nothing “in” the mind, but only objects “before” it. Berkeley
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discusses the view that we must distinguish the act of perceiving from the object perceived, and that the former is mental while the latter is not. His argument against this view is obscure, and necessarily so, since, for one who believes in mental substance, as Berkeley does, there is no valid means of refuting it. He says: “That any immediate object of the senses should exist in an unthinking substance, or exterior to all minds, is in itself an evident contradiction.” There is here a fallacy, analogous to the following: “It is impossible for a nephew to exist without an uncle; now Mr. A is a nephew; therefore it is logically necessary for Mr. A to have an uncle.” It is, of course, logically necessary given that Mr. A is a nephew, but not from anything to be discovered by analysis of Mr. A. So, if something is an object of the senses, some mind is concerned with it; but it does not follow that the same thing could not have existed without being an object of the senses.
There is a somewhat analogous fallacy as regards what is conceived. Hylas maintains that he can conceive a house which no one perceives, and which is not in any mind. Philonous retorts that whatever Hylas conceives is in his mind, so that the supposed house is, after all, mental. Hylas should have answered: “I do not mean that I have in mind the image of a house; when I say that I can conceive a house which no one perceives, what I really mean is that I can understand the proposition ‘there is a house which no one perceives,’ or, better still, ‘there is a house which no one either perceives or conceives.'” This proposition is composed entirely of intelligible words, and the words are correctly put together. Whether the proposition is true or false, I do not know; but I am sure that it cannot be shown to be selfcontradictory. Some closely similar propositions can be proved. For instance: the number of possible multiplications of two integers is infinite, therefore there are some that have never been thought of. Berkeley’s argument, if valid, would prove that this is impossible.
The fallacy involved is a very common one. We can, by means of concepts drawn from experience, construct statements about classes some or all of whose members are not experienced. Take some perfectly ordinary concept, say “pebble”; this is an empirical concept derived from perception. But it does not follow that all pebbles are perceived, unless we include the fact of being perceived in our definition of “pebble.” Unless we do this, the concept “unperceived pebble”
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is logically unobjectionable, in spite of the fact that it is logically impossible to perceive an instance of it.
Schematically, the argument is as follows. Berkeley says: “Sensible objects must be sensible. A is a sensible object. Therefore A must be sensible.” But if “must” indicates logical necessity, the argument is only valid if A must be a sensible object. The argument does not prove that, from the properties of A other than its being sensible, it can be deduced that A is sensible. It does not prove, for example, that colours intrinsically indistinguishable from those that we see may not exist unseen. We may believe on physiological grounds that this does not occur, but such grounds are empirical; so far as logic is concerned, there is no reason why there should not be colours where there is no eye or brain.
I come now to Berkeley’s empirical arguments. To begin with, it is a sign of weakness to combine empirical and logical arguments, for the latter, if valid, make the former superfluous. * If I am contending that a square cannot be round, I shall not appeal to the fact that no Square in any known city is round. But as we have rejected the logical arguments, it becomes necessary to consider the empirical arguments on their merits.
The first of the empirical arguments is an odd one: That heat cannot be in the object, because “the most vehement and intense degree of heat [is] a very great pain” and we cannot suppose “any unperceiving thing capable of pain or pleasure.” There is an ambiguity in the word “pain,” of which Berkeley takes advantage. It may mean the painful quality of a sensation, or it may mean the sensation that has this quality. We say a broken leg is painful, without implying that the leg is in the mind; it might be, similarly, that heat causes pain, and that this is all we ought to mean when we say it is a pain. This argument, therefore, is a poor one.
The argument about the hot and cold hands in lukewarm water, strictly speaking, would only prove that what we perceive in that experiment is not hot and cold, but hotter and colder. There is nothing to prove that these are subjective.
In regard to tastes, the argument from pleasure and pain is repeated: Sweetness
