Descartes vs. Berkeley 03/05/95


In Descartes\' First Meditation, Descartes writes that he has
come to the conclusion that many of the opinions he held in his
youth are doubtful, and consequently all ideas built upon those
opinions are also doubtful. He deduces that he will have to
disprove his current opinions and then construct a new foundation
of knowledge if he wants to establish anything firm and lasting in
the sciences that is absolutely true. But rather than disprove
each of his opinions individually, Descartes attacks the principles
that support everything he believes with his Method of Doubt. The
Method of Doubt is Descartes\' method of fundamental questioning in
which he doubts everything that there is the slightest reason to
doubt. It should be mentioned that Descartes does not necessarily
believe that everything he doubts is true. He does believe,
however, that whatever can not be doubted for the slightest reason
must be true.
Descartes spends Meditation One trying to disprove his
fundamental beliefs. First, Descartes doubts that his senses are
generally trustworthy because they are occasionally deceitful (eg.
a square tower may look round from far away). Also, because he
realizes that there are no definitive signs for him to distinguish
being awake from being asleep, he concludes that he can not trust
his judgement to tell him whether he is awake or asleep. But
asleep or awake, arithmetic operations still yield the same answer
and the self-preservation instinct still holds. To disprove these,
Descartes abandons the idea of a supremely good God like he has
believed in all his life and supposes an evil genius, all-powerful
and all-clever, who has directed his entire effort at deceiving
Descartes by putting ideas into Descartes\' head.
With these three main doubts, each progressively more broad,
Descartes finally is satisfied that he has sufficiently disproved
his previous opinions. He now is ready to build a new foundation
of knowledge of a physical world (the real world) based on what
must absolutely be true.
Berkeley, however, would argue that Descartes is wasting his
time by trying to discover what must be absolutely true in the real
world. In his Dialogue One, Berkeley argues that there is no real
world, and that all sensible objects (those which can be
immediately perceived) exist only in the mind. He starts by
proving that secondary (extrinsic) qualities exist only in the mind
by use of the Relativity of Perception Argument. As an example,
Berkeley writes that if you make one of your hands hot and the
other cold, and put them into a vessel of water, the water will
seem cold to one hand and warm to the other. Since the water can
not be warm and cold at the same time, it must follow that heat (a
secondary quality) must only exist in the mind. Berkeley also uses
the qualities of taste, sound, and color as examples to prove that
all secondary qualities must reside in the mind.
However, Berkeley also says the same argument can be applied
to primary (intrinsic) qualities. He writes that to a mite, his
own foot might seem a considerable dimension, but to smaller
creatures, that same foot might seem very large. Since an object
can not be different sizes at the same time, it follows that
extension must exist only in the mind. Further, since all other
primary characteristics can not be separated from extension, they
too must exist only in the mind.
An interesting aspect of Descartes\' Dualistic view and
Berkeley\'s Idealistic view is the necessity of God. Descartes
needs an all-good non-deceiving God to insure that the ideas of
primary qualities of objects he perceives in his mind accurately
represent those qualities of objects in the external world. In the
Third Meditation, Descartes says that God is infinite and finite is
the lack of infinite. Infinite, he says, is NOT the lack of
finite. Since our concept of the infinite could not have come from
the concept of the finite (since infinite is not the lack of
finite), the idea of infinite could only have come from God. This
proof is shaky at best.
Berkeley, on the other hand, needs God to give us the ideas of
the objects we see since there is no physical world to draw those
ideas from through the senses. But rather than proving God to
prove his philosophy, Berkeley uses his philosophy as the proof of
God\'s existence. In his Second Dialogue, Berkeley says God must
exist to put the same real ideas into everybody\'s minds because
minds cannot interact directly. However, if it were the case that
God did not actually exist (or had used his infinite powers