In
A Treatise Concerning the Principles of Human Knowledge, Berkeley's argument is less than convincing, I think because he is, as Socrates puts it in
Crito, writing as an advocate rather than a philosopher. It is clear that his
a priori is the existence of God, and that God is the creator of our experiences, though he seems to deny the idea that we live inside God's experience, in God's dream so to speak.
Which takes us to Schopenhauer, who writes--and thinks--more speculatively than Berkeley. I particularly like the passage below, from
The World as Will and Idea Vol. 1, (Haldane/Kemp translation) where Schopenhauer picks up that fluffy pseudo-philosophical musing about whether we live in a dream, and carries it as far a it will go. Fun, but not fluffy.
We
have dreams;
may not our
whole life be a dream? or more exactly:is there a
sure
criterion of the distinction between dreams and reality?
between
phantasms and real objects ? The assertion that
what
is dreamt is less vivid and distinct than what we ac-
tually
perceive is not to the point, because no one has ever
been
able to make a fair comparison of the two ; for we
can
only compare the recollection of a dream with the
present
reality. Kant answers the question thus : " The
connection
of ideas among themselves, according to the
law
of causality, constitutes the difference between real
life
and dreams." But in dreams, as well as in real life,
everything
is connected individually at any rate, in
accordance
with the principle of sufficient reason in all
its
forms, and this connection is broken only between
life
and dreams, or between one dream and another.
Kant's
answer therefore could only run thus : — the long
dream
(life) has throughout complete connection accord-
ing
to the principle of sufficient reason ; it has not this
connection,
however, with short dreams, although each of
these
has in itself the same connection: the bridge is
therefore
broken between the former and the latter, and
on
this account we distinguish them.
But
to institute an inquiry according to this criterion,
as
to whether something was dreamt or seen, would
always
be difficult and often impossible. For we are by
no
means in a position to trace link by link the causal
connection
between any experienced event and the present
moment,
but we do not on that account explain it as
dreamt.
Therefore in real life we do not commonly
employ
that method of distinguishing between dreams
and
reality. The only sure criterion by which to dis-
tinguish
them is in fact the entirely empirical one of
awaking,
through which at any rate the causal connec-
tion
between dreamed events and those of waking life, is
distinctly
and sensibly broken off. This is strongly
supported
by the remark of Hobbes in the second chapter
of
Leviathan, that we easily mistake dreams for reality
if
we have unintentionally fallen asleep without taking
off
our clothes, and much more so when it also happens
that
some undertaking or design fills all our thoughts,
and
occupies our dreams as well as our waking moments.
We
then observe the awaking just as little as the falling
asleep,
dream and reality run together and become con-
founded.
In such a case there is nothing for it but the
application
of Kant's criterion ; but if, as often happens,
we
fail to establish by means of this criterion, either the
existence
of causal connection with the present, or the
absence
of such connection, then it must for ever remain
uncertain
whether an event was dreamt or really hap-
pened.
Here, in fact, the intimate relationship between
life
and dreams is brought out very clearly, and we need
not
be ashamed to confess it, as it has been recognised
and
spoken of by many great men. The Vedas and
Puranas
have no better simile than a dream for the
whole
knowledge of the actual world, which they call
the
web of Maya, and they use none more frequently.
Plato
often says that men live only in a dream; the
philosopher alone strives to awake himself. (20-21)
, which he calls a
But what distinguishes the false
philosopher from the true is this : the perplexity of the latter arises from
the contemplation of the world itself, while that of the former results from
some book, 