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 is a pleasure and
bitterness a pain, therefore both are mental.
* E.g., "I was not drunk last night. I had only had two glasses; besides, it is well known that I
am a teetotaller."