"Hold, Philonous, I now see what it was deluded me all this time. You asked me whether heat and cold, sweetness and bitterness, were not particular sorts of pleasure and pain; to which I answered simply that they were. Whereas I should have thus distinguished:—those qualities as perceived by us, are pleasures or pains; but not as existing in the external objects. We must not therefore conclude absolutely, that there is no heat in the fire, or sweetness in the sugar, but only that heat or sweetness, as perceived by us, are not in the fire or sugar."[276:8]
The Application of the Epistemological Principle.
§ [130]. Here the argument touches upon profound issues. Philonous now assumes the extreme empirical contention that knowledge applies only to its own psychological moment, that its object in no way extends beyond that individual situation which we call the state of knowing. The full import of such an epistemology Berkeley never recognized, but he is clearly employing it here, and the overthrow of Hylas is inevitable so long as he does not challenge it or turn it against his opponent. This, however, as a protagonist of Berkeley's own making, he fails to do, and he plays into Philonous's hands by admitting that what is known only in perception must for that reason consist in perception. He frankly owns "that it is vain to stand out any longer," that "colors, sounds, tastes, in a word, all those termed secondary qualities, have certainly no existence without the mind."[277:9]
Hylas has now arrived at the distinction between primary and secondary qualities. "Extension, Figure, Solidity, Gravity, Motion, and Rest" are the attributes of an external substance which is the cause of sensations. But the same epistemological principle readily reduces these also to dependence on mind, for, like the secondary qualities, their content is given only in perception. Hylas is then driven to defend a general material substratum, which is the cause of ideas, but to which none of the definite content of these ideas can be attributed. In short, he has put all the content of knowledge on the one side, and admitted its inseparability from the perceiving spirit, and left the being of things standing empty and forlorn on the other. This amounts, as Philonous reminds him, to the denial of the reality of the known world.
"You are therefore, by your principles, forced to deny the reality of sensible things; since you made it to consist in an absolute existence exterior to the mind. That is to say, you are a downright sceptic. So I have gained my point, which was to show your principles led to Scepticism."[278:10]
The Refutation of a Conceived Corporeal World.
§ [131]. Having advanced the direct empiricist argument for phenomenalism, Berkeley now gives the rationalistic motive an opportunity to express itself in the queries of Hylas as to whether there be not an "absolute extension," somehow abstracted by thought from the relativities of perception. Is there not at least a conceivable world independent of perception?
The answers of Philonous throw much light upon the Berkeleyan position. He admits that thought is capable of separating the primary from the secondary qualities in certain operations, but at the same time denies that this is forming an idea of them as separate.
"I acknowledge, Hylas, it is not difficult to form general propositions and reasonings about those qualities, without mentioning any other; and, in this sense, to consider or treat of them abstractedly. But, how doth it follow that, because I can pronounce the word motion by itself, I can form the idea of it in my mind exclusive of body? or, because theorems may be made of extension and figures, without any mention of great or small, or any other sensible mode or quality, that therefore it is possible such an abstract idea of extension, without any particular size or figure, or sensible quality, should be distinctly formed, and apprehended by the mind? Mathematicians treat of quantity, without regarding what other sensible qualities it is attended with, as being altogether indifferent to their demonstrations. But, when laying aside the words, they contemplate the bare ideas, I believe you will find, they are not the pure abstracted ideas of extension."[279:11]