Summary
Meditations on First Philosophy begins
with two introductions. The first is addressed to the theology faculty
at the Sorbonne (a university in Paris), the second to his lay readers.
He outlines some of the objections to the Discourse and
asserts that his critics generally ignored his chains of logic and
only attacked his conclusions. He pledges to return to the two criticisms
he finds worth considering. He asks his readers to approach the
rest of the book with an unbiased mind.
The first meditation reiterates material from the Discourse. Responding
to an objection to his critique of the senses, Descartes agrees
that he would seem a madman if he argued he was not sure that he
possessed a body. But he also points out that in his dreams he experiences
a reality as convincing as his waking reality. He can find no sure
way to distinguish between waking life and sleep. He then goes on
to argue that if we dream of hands, feet, eyes, and bodies, then
they must actually exist. When we dream, he continues, we use information
we gathered from reality. Even if particular complex objects do
not exist, at least the basic colors and shapes that compose them
exist. In the same way, we can say the physical sciences are uncertain
because they study composites. Arithmetic and geometry study simple
objects (shapes, angles, numbers) and are therefore trustworthy.
He trusts his perceptions of self-evident truths such as simple
shapes and numbers because he believes in an all-powerful God that
created these things.
Descartes admits that he cannot be sure that God is not
playing some sort of trick on him. However, because he believes
that God is good, he knows that God would not deliberately deceive
him. Therefore, to rebuild his knowledge on the basis of doubt,
he decides to pretend that a “malignant demon” is bent on tricking him.
This powerful demon has created the illusions of the physical world
to deceive him. With this in mind, Descartes sets out to prove, using
only reason, that some things are beyond doubt.
Most of meditation II is devoted to discovering whether
there is anything about which Descartes can be absolutely certain.
First he decides he can be certain that he exists, because if he
doubts, there must be a thinking mind to do the doubting. He does
not yet accept that he is a thinking mind inside a body. After all,
the demon could have convinced him that his body and the physical
world exist. He moves to another question: what is the “I” that
is doing the thinking?
The answer is that the mind is a purely thinking thing.
Descartes concedes, however, that though what he perceives with
his senses may be false, he cannot deny that he perceives. So the
human mind is capable of both thought and perception. He explains
this using the example of a piece of wax. We understand that solid
wax and wax melted by a candle are both wax. Therefore perception
is not strictly a function of the senses. It must be the reasoning
mind that makes this judgment. Because the senses can be deceived,
physical objects, including bodies, are properly perceived only
by the intellect, and the mind is still the only thing he can be
certain exists.
In meditation III, Descartes says he can be certain that
perception and imagination exist, because they exist in his mind
as “modes of consciousness,” but he can never be sure whether what
he perceives or imagines has any basis in truth. He then expands
on his argument for the existence of God from the Discourse.
He examines his own mind to see whether there is anything in him
that would allow him to make God up. Not only is God perfect, but
God is also infinite and all powerful. Descartes knows that he himself
is finite. He reasons that it is not possible for a finite being
to dream of infinity. Therefore the idea of the infinite must come
before the idea of the finite, before any person can begin to think
of what he or she is.
