2. In Berkeley's “Principles of Human Knowledge” the argument is concerned
with certain ideas-a question which arises for all philosophers
from Descartes and which is particularly concerned with the relation of
ideas to existence and the extent to which we can rely upon our ideas
to discover what existence is; and the question then is whether the
division between ideas and realities really crops up and further whether
we may bridge the gap. Berkely, then, sets out to discuss human knowledge
and in this respect he resembles the so-called empiricists as well as
Descartes who sets out to find which among the things we suppose ourselves
to know, we can be perfectly sure of; i.e., he takes as the task of
the philosopher the removal of error and the establishment of some
absolutely certain truth. Now philosophers would generally agree that
philosophy is concerned with truth, but it does not follow that philosophy
should be concerned with our ability, as persons, to recognise truth
or with a division among truths such that some are matters of certainty,
others of uncertainty. It may be argued, on the contrary, that while
philosophy will investigate the nature of truth and, as connected therewith,
the nature of error it does not consider (or, at least, is not bound
to) how far we, as human beings, are capable of knowing truth. On the
other hand it would be maintained by some that the question could not be
separated from a consideration of human faculties and if that were so
then philosophy, conceived as a study of truth, would involve a study of
human capacities, of the mind's capacity for knowledge.

Now part of the difficulty in connection with questions of this
kind arises from an ambiguity of terms, the term knowledge particularly
being subjected to this ambiguity. When we speak of our knowledge we
may mean one of two things:- (a) what we know, i.e., the particular facts
we are aware of, (b) the fact that we know it. The expression “knowledge”
is now used in both senses so it is very important to know when it
is being used in one sense and when in the other and likewise not to
confuse the two senses together. Now it is on the basis of that ambiguity
that we have the controversy between realists and idealists. What
the realists, in effect, say is that the arguments of the idealists are
based upon a confusion between the two meanings of the word “knowledge”
and what the idealists substantially maintain is that there are only
apparently two meanings, that in reality there is only one.

As far as Berkeley is concerned we do not have the confusion in
quite so pronounced a form as in the works of some others. Berkeley
quite clearly and distinctly distinguishes between what we know and
ourselves in the act of knowing it. What he does insist upon is that
what we know, our knowledge, consists of ideas and that those ideas, in
virtue of being ideas, are in the mind. It follows, then, that if what we
know is always in the mind--owing to the fact that it is known to us--

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we can never know anything outside the mind and thus Berkeley supposes
himself to have refuted the doctrine of Locke and Descartes, namely, that
we can have knowledge of matter as a non-mental substance existing on
its own account in space and time. What we call matter, he says, consists
in reality of nothing but ideas and exists nowhere but in the mind. But
still, he says, he had not removed any part of reality as it is commonly
understood--he has only removed a false view of its nature and connections.
Allowing that we know it does exist outside the mind, stil, according
to Berkeley, it really does exist inside the mind and it is distinguishable
from those mental processes by which we are aware of it.

It is necessary if this argument is to be of value that it should
determine what is meant precisely by an idea. It is to be remembered
that in using idea in the way he does, he adapts the use essentially made of it by
his predecessors, namely, that they, while accepting a cert in nature of ideas,
applied other things to ideas not properly so. Popularly speaking, we
should say Berkeley's views are incorrect--this is the commonsense view.
However it may be that Berkeley does not really mean what he says; while
we may point out inconsistencies we must show that the inconsistence is
from him and not from us.

Berkeley begins by making a survey of the objects of human knowledge.
These objects, he says, may be:
I. Ideas actually imprinted on the senses,
II. Ideas perceived by attending to the passions and operation of the mind,
III. Those forged by the help of memory and imagination using as their
material, ideas mentioned in I. And II.---in other words, memory and imagination,
working on I and II, may produce new things. These, according to
Berkeley are his ideas. According to this classification it would seem
that we are aware of ideas and nothing but them, but in the second paragraph
he says that, “besides all the endless variety of ideas or objects
of knowledge, there is something likewise which knows or perceives them an
and exercises various operations such as willing, imagining, remembering
about them”---”This perceiving active being is what I call mind, spirit,
soul or myself”, “By which words,” he says, “I do not denote anyone of my
ideas but a thing entirely distinct from them wherein they exist---
whereby they are perceived; for the existence of an idea consists”, he
concludes, “in being perceived”. In addition to my ideas, then, Berkeley
maintains that the something which knows them is what I call my mind or
myself. But we are not entitled, he argues, to postulate external things
existing beyond these ideas and causing them to appear in our minds. If
we have any idea of these things, then what we have is an idea and we are
no nearer the things than we were before. In this way Berkeley rejects
the theory of Descartes and Locke, namely, that ideas were in some intermediate
position between us and things, representing the things to our
minds and thus enabling us to know them. This is the doctrine of
representative perceptions; knowing things by means of ideas or mental
representations is rejected by Berkeley because he argues that whatever
knowledge we get of these supposed things by means of representation or
in any other way must consist entirely of ideas, so that one way of putting
Berkeley's position is to say that he maintains that we cannot
divide knowledge into two parts, namely, into knowledge of external things

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and knowledge of their mental representations. Thus we must give up
either one or the other; so we may say either that we know external things
without the mediation of ideas, i.e., directly or else that we know only
ideas and then the conception external thing is a meaningless one.
Now it is the latter view that Berkely himself takes and even if this
view can be shown to be erroneous, still it is possible to maintain that
Berkeley shows that the theory of Locke and Descartes is incorrect and
further that if we do not want to be entirely limited to ideas, then we
must completely abandon the doctrine and think of knowledge as consisting
of a direct dealing with things.