In Rene Descartes Meditations on First Philosophy, Descartes
is seeking to find a system of stable, lasting and certain knowledge,
which he can ultimately regard as the Truth. In his methodical
quest to carry out his task Descartes eventually arrives at the
proverbial fork in the road: how to bridge the knowledge of self
with that of the rest of the world. Descartes answer to this is
to prove the existence of God. The purpose of this essay will
be to state and explain Descartes' Third Meditation Proof of God's
Existence by (1) identifying relevant concepts/ terminology and
there relationship to each other, (2) examining each premise as
well as the conclusion of the proof and finally (3) to comment
on the significance of the proof in the context of the Evil Genius
assumption.
In order to begin explaining the meaning and significance of
Descartes' Third Meditation Proof of God's Existence we must begin
by defining some of the terms and concepts used in the proof.
The first of these concepts deals with kinds of reality. By
this we are concerned with reality's relationship to the mind.
The two kinds of reality introduced are subjective and formal.
Subjective reality involves those things which are mind dependent,
more commonly thought of as ideas. An example of this would be
Prof. Wishart's purple unicorn. While this entity may hold significance
and form to her, it is quite literally impossible for anyone else
to imagine this entity in the same way. In effect, outside the
contents of her thinking mind the purple unicorn holds no sustenance
or relative importance to anyone else. In contrast, formal reality
deals with those things that are independent of the mind's "treasury",
in other words the actual entity An example of this would be the
lectern in class. It is an object which possesses both discernible
and tangible characteristics capable of being verified by all
those who observe it, even without previous knowledge of such
objects. It should also be noted that objects of formal reality
are generally the cause of objects of subjective reality.
The second concept we must examine in order to fully appreciate
Descartes' Third Meditation Proof of God's Existence concerns
Degrees of Reality. By this we mean a ranking of the representative
qualities of either kind of reality. The lowest degree of reality
deals with accidents and modifications, things which are characteristics
or expressions of objects with a higher degree of reality. An
example of this would be the individual holes and marks on the
classroom ceiling. These characteristics cannot exists by themselves
and are thus subject to the existence of things in the next highest
degree of reality, that of substances. Substances are finite objects
or ideas with conceivable limits. In the previous example, the
ceiling itself is the substance with the holes and markings (of
a lower degree of reality) being dependent upon it for their continued
existence. The highest degree of reality involves the infinite.
The infinite represents substances that are unbounded and possess
no conceivable or tangible limits in any of their aspects or qualities.
The only example of this for Descartes would be an entity of omnipotence,
who would be all knowing, all powerful, and that of which no greater
can be conceived, in other words God.
The next concept that must be explained is in fact the very
first premise for Descartes' Third Meditation Proof for the Existence
of God, that of the Causal Adequacy Principle. Descartes reasons
that "as the idea contains one particular subjective reality
rather than another, it must get this reality from a cause having
at least as much formal reality as the idea has subjective reality"
(p 58). In this, Descartes attempts to tie together the concepts
on kinds of reality and degrees of reality. Returning to the example
using the ceiling, Descartes would argue that the thing causing
or bringing into existence the idea of the ceiling (a mind dependent
entity) could only be another finite substance (i.e. the actual
ceiling) or an infinite substance (i.e. God), either of which
would be of formal (mind independent) reality. In saying this
we eliminate the notion that the idea of the ceiling could be
sustained by the holes and markings (accidents and modifications)
because according to Descartes they are of a lower degree of reality,
and what is of lower degree cannot of itself bring about something
of a higher degree.
The second premise of Descartes Third Meditation Proof of God's
Existence stems from introspection, that is, Descartes direct
mental inspection his thoughts as a thinking thing. In this Descartes
recounts what he knows to be true up to this point. He concludes
that what little things he knows such as substance, duration ,
number, and extension, shape , place, and motion are no greater
than himself and indeed may be in him eminently. He considers
these things to be as finite as he is. But now, we introduce a
further revelation of Descartes mind, that of his conception or
idea of an infinite substance. In this he means a substance that
is "independent, supremely intelligent and supremely powerful"
(p. 60). Moreover, a substance which extends beyond the bounds
of his minds and in whom lies the limitless concepts of both things
that he can and cannot perceive.
At this point we should call attention to the significance
of Descartes' thinking. One of the qualities Descartes assumes
about himself is that his power of conception is far greater than
the power of his imagination. Thus he conceive of a great many
objects and ideas such as the chiliagon (a thousand sided figure)
that he will forever remain hopeless to be able to grasp a mental
image of. The second point that should be brought to light is
the inherent concept of understanding the of the infinite before
you can grasp the finite. To this Descartes thinks in terms of
the infinite as the absence of limits in the same way that he
thinks of rest as the absence of motion and light as the absence
of darkness (p. 60). The specific relevance of this point to Descartes'
proof will be discussed in the next section
The logical conclusion of Descartes Third Meditation for God's
existence is that in fact an infinite substance (i.e. God) must
exists: "I who am finite would not have the idea of an infinite
substance in me unless it came from a substance that really was
infinite (p. 60). Descartes knows that cannot have been the cause
of such a substance because he himself is of a lower degree of
reality than God. Thus to Descartes this infinite substance would
have all the conceivable qualities Descartes can ascribe to an
infinite degree. Moreover, in returning to the point about the
concept of the infinite before the finite, Descartes speculates
that his concept of an infinitely perfect God must be prior knowledge
to his still as yet limited understanding of his flawed and imperfect
self.
This proof of God's Existence discount the earlier possible
existence of an Evil Genius. Because Descartes has shown God to
be an infinite substance clearly not of his own minds' creation,
but in fact a limitless being with infinite powers including those
of power and goodness. This first quality alone is enough to dismiss
the Evil Genius for there can only be room enough for one all
powerful being and if in fact God is that being than that leaves
no room for another. Furthermore, since God possesses infinite
goodness it would seem contrary to his nature to engage us in
a continual deception based on either our apriori or aposteriori
beliefs.
In conclusion, Descartes' Third Meditation Proof of God's Existence
represents a critical step in Descartes overall goal of obtaining
a system of certain, lasting, and stable knowledge: that of using
the existence of God to bridge the gap between knowledge of self
and knowledge of the external world. In building this bridge we
must first define the different kinds and degrees of reality and
how they relate to one another. From this we are able to see the
logic behind Descartes Causal Adequacy Principle, follow his second
premise, and reach the same inevitable conclusion that Descartes
does: that an infinite unbounded substance through which all conceivable
qualities without end (i.e. God) must exists. For Descartes' this
will lay the very foundation for him to expand beyond his limited
thinking mind and begin to explore the very depths of the universe
in his quest to find the Truth.