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