7. Now although the position of Berkeley is regarded as sceptical
in effect, he really set out to refute scepticism. Having established
to his own satisfaction that the existence of things consists in their
being known by minds and that that is therefore a relative or dependent
existence, Berkeley is bound to regard as erroneous the views of those
who think that there are independent or non-mental existences. Now
this view is found in two different forms. On the one hand there is

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vulgar opinion or commonsense opinion that things which we see and
otherwise directly perceive have an independent existence in the vary
form in which we perceive them; and on the other hand, there is the view
of philosophy, and in this connection Berkeley is thinking principally
of Locke, that things which we immediately perceive do not have independent
existence but they represent or symbolise some other things which
do have independent existence, i.e., material bodies.

A material body, according to Locke, is not something which is directly
perceived, i.e, not an “idea” or sensation but it is that which
causes us to have certain ideas and of which we have indirect information
through these ideas; so that in opposing the commonsense view
Berkeley is in agreement with Locke and his predecessors. On the other
hand, in his opposition to Locke he is, to a certain extent, he is in agreement
with the commonsense view in considering, namely, that there is
nothing behind what we perceive but that the things which we perceive
are the real objects. That at least is Berkeley's initial position
and he combats very strongly the representative theory of Locke, but he
himself goes on to adopt a different representative theory, namely, that
what lies behind the ideas we receive is the working of mind. But his
theory is less vulnerably than Locke's so long as the Cartesian assumption
of an intuitive knowledge of our own minds and their working upon
ideas is made because if we grant so much, then we are acquainted, within
our own minds, with mental operations upon ideas and consequently we can,
at least, significantly form the hypothesis that if in those cases in
which we are not immediately aware of mental operations performed upon
ideas, such operations have nevertheless been performed.

On the other hand, according to Locke's own admission, we have no
immediate or intuitive knowledge of the working of matter upon ideas--matter
is something which does not enter into our own minds and thus the
theory that there are material causes of ideas is the merest guesswork
and we have no means of showing what these material causes would
be like; in other words, we have no means of defining the term “matter”
and Locke is able to make his argument plausible, to appear to give a
satisfactory description of the constitution of matter solely because
he does not adhere to his initial assumption but argues, in certain parts
of his discussion as if the things of which we were immediately aware,
which he had previously called ideas, were material bodies themselves.

Hence Berkeley is easily able to show that Locke is inconsistent
and that he may say either that we have no knowledge of matter whatsoever
or that, in accordance with the commonsense view, the things which we
immediately perceive are material bodies. Now while Berkeley relies,
to a certain extent, on Locke's explicit agreement with him that the
commonsense view as false, he also argued independently in order to
show that it was false and this demonstration that the things that we
are aware of are only ideas must accordingly be taken as the most important
part of his whole argument.

Berkeley says, then, in paragraph IV. that “It is indeed an opinion
strangely prevailing amongst men, that houses, mountains, rivers, and in a
word all sensible objects have an existence natural or real, distinction
from their being perceived by the understanding”. But tis view,
Berkeley says, involves a “manifest contradiction”; “For what are the
aforementioned objects but the things we perceive by sense, and what do
we perceive besides our own ideas or sensations; and is it not plainly
repugnant that any one of these or any combination of them should exist

  ― 13. ―
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unperceived?”. And Berkeley goes on in the important fifth paragrat h
to say that the cause of this error is the doctrine of abstract ideas
, a doctrine against which he has argued in detail in the introduction.

Now it certainly seems strange that this philosophical doctrine
which Berkeley had associated particularly with the work of Locke
should be the cause of the errors made by commonsense; and this, in itself,
while it is not a conclusive objection would lead one from the
beginning to doubt the validity of Berkeley's criticism of abstract
ideas or else to doubt the correctness of associating that doctrine
with the beliefs of commonsense.

Now the way in which Berkeley expresses the abstraction involved
in the opinion he is criticising is to ask the question, “Can there
be a nicer strain of abstraction than to distinguish the existence of
sensible objects from their being perceived, so as to conceive the existing
unperceived?”. “For my part,” he says, “I might as easily
divide a thing from itself”. Now this argument in relation to the
general discussion of abstraction introduces the most important point
in Berkeley's theory, and if this point is established, then apart from
minor details his theory as a whole may be said to <sic?> established. On
the other hand, if we can show his argument to be fallacious at this
point, then his whole position is shown to be unsound even if he does
exhibit, in his general argument, a certain amount of solid reasoning.

Now in this particular argument we have an ambiguity similar to
that which we found in connection with his argument about the perception
of tables, though slightly different in form; in the previous case
we had an ambiguity of construction; in this case we have a single
ambiguous term and that is the term “sensible”. When we speak of a
sensible thing we should naturally take this to mean a thing which can
be perceived and, although it might be the case that everything that
can be perceived actually is perceived, we should not find any contradiction
in saying that it was not. Either assertion would require
distinct proof. On the other hand, if we take a sensible thing to be a
thing which is perceived, then there would naturally be a contradiction
in saying that it is not perceived. Now Berkeley relies upon this
ambiguity to obtain assent to the proposition that “All sensible
things are perceived and have no existence apart from being perceived”.

But when the ambiguity has once been made plain, we should
naturally expect that some things which could be perceived might
happen not to be perceived, i.e., that a mountain or a river which at
one time we perceive might not be perceived by us ar another time and
yet might continue to exist. But that ambiguity is really distinct
from the fundamental difficulty about the argument. In connection
with it we have the suggestion that what can be perceived i s perceived
but there is the further suggestion, on which Berkeley's whole position
depends, that what is perceived must be perceived, i.e., that its being
perceived is a matter of necessity or the thing's very nature or
essence. It is this theory of essences that is at the root of Berkeley's
position just as of Descartes'.