154
INSTITUTES OF METAPHYSIC.
PROP. V.————
qualities, we rest the establishment of the independent existence of matter.
This refutation, if logically conclusive, is founded on a contradiction and therefore cannot be accepted.10. There appears at first sight to be some force in that argument, but before it can be accepted as valid, one or two small circumstances must be taken into consideration. It is not enough to show that sensation is different from perception, and that the primary are different from the secondary qualities; the psychologist must moreover show, or, at least, must assume, that the primary qualities are known per se, or without the "me" being known along with them. Unless he assumes this his argument is good for nothing. His object is to prove that material things have an existence altogether independent of intelligence. Perhaps they have; but how can that conclusion be logically reached by merely affirming that extension, figure, and solidity are not of a sensational character, and that the primary qualities are different from the secondary? This doctrine must be coupled with the assertion, that the primary qualities are known in their independency, otherwise the conclusion that they are independent can have nothing to rest upon. The psychological argument, therefore, when stripped of its wrappings and presented in plain language, amounts to this:—certain qualities of matter, namely, the primary, are known to exist per se; therefore these qualities, and the matter in which they inhere, do exist per se. But
