Descartes’ Epistemology
• Epistemology: The philosophical
examination of knowledge – its nature and its
origin.
• Rationalism: Epistemological school that
maintains that the most important truths about
reality are obtained by means of the intellect
(the mind) alone, without relying at all upon
the senses.
Descartes’ World
• Descartes lived during the first half of
the Seventeenth Century (1596 – 1649).
• A Revolutionary and Uncertain Time
– Copernicus
– Galileo
– Kepler
– Reformation (1520)
– Thirty Years War (1619 – 1648)
• Europe’s pop. shrank by 6.5 million
during this war.
Descartes’ Motivation
• Descartes was a mathematical genius.
Developed the x y graphing grid still
used today (the Cartesian point
system).
• Given the times in which he lived and
his temperament, Descartes wanted to
find the same certainty in philosophy
that he found in mathematics.
Descartes’ Method of Systematic
Doubt
• Descartes resolved to doubt anything
that could be doubted.
• He was looking for at least one totally
indubitable, absolutely certain truth
upon which he could build his entire
philosophy.
• He was looking for a philosophical
Archimedean point.
– “Archimedes, in order that he might
draw the terrestrial globe out of its
place, and transport it elsewhere,
demanded only that one point should
be fixed and immoveable; in the same
way, I shall have the right to have
high hopes, if I am happy enough to
discover one thing only which is
certain and indubitable.”
Rene Descartes, Meditations on First
Philosophy
• N. B.: Descartes engages in
philosophical, NOT genuine, doubt.
Despite the hyperbole he sometimes
employs, Descartes does not really
doubt the things he says he does;
rather, he rejects as his philosophical
Archimedean point anything that can be
doubted.
• What can be doubted?
– The reports of the senses.
• Dreams sometimes mistaken for
reality.
– “How often has it happened to me that
in the night I dreamt that I [was] in this
particular place, that I was dressed and
seated near the fire, whilst, in reality, I
was lying undressed in bed . . . ! [I]n
dwelling carefully on this reflection I
see so manifestly that there are no
certain indications by which we may
clearly distinguish wakefulness from
sleep . . . .”
Meditations on First Philosophy
• Since in his dreams he’s dreamed
that he’s had all sorts of strange,
grotesque bodies, Descartes
realizes that his belief that he has a
body at all could be false; so, he
will doubt even that.
– A very powerful, very evil genius
(sort of a super Satan) might be
continually deceiving Descartes even
about his mathematical beliefs, e.g.
2+2=4; so, he will doubt even these.
• What cannot be doubted?
– “. . . let him [the evil genius] deceive
me as much as he will, he can never
cause me to be nothing so long as I
think that I am something. So that,
after having reflected well . . . we
must come to the definitive
conclusion that this proposition, I am,
I exist, is necessarily true each time
that . . . I mentally conceive it.
Meditations on First Philosophy
– Cogito, ergo, sum. “I think; therefore,
I am” from Descartes’ Discourse on
Method.
– In order for the evil genius to deceive
him, Descartes must exist because
something that does not exist cannot
be deceived.
– But, what is Descartes, i.e. what
type of being is he?
• “I am not more than a thing which
thinks, that is to say a mind or a
soul, or an understanding, or a
reason . . . . I am . . . a real thing
and really exist; but what thing? I
have answered: A thing which
thinks”
Meditations on First Philosophy
• Descartes has found his philosophical
Archimedean point – his own existence
as a mind.
Clear and Distinct Standard
• “[Since] there [is] nothing at all in the
statement ‘I think; therefore, I am’ which
assures me of having, thereby, made a
true assertion, excepting that I see very
clearly that to think is necessarily to be,
I came to the general conclusion that I
might assume, as a general rule, that
the things which we conceive very
clearly and distinctly are all true . . . .”
Meditations on First Philosophy
• Descartes will accept as true any idea
that he conceives as clearly and
distinctly as the idea that he exists as a
mind.
The Eidological Proof for God
• Descartes has an idea of perfection, i.e. of
God
• God is “infinite, eternal, immutable,
independent, all knowing, all powerful, and
[the Being] by Whom I myself and everything
else . . . have been created.”
Meditations on First Philosophy
• Descartes clearly and distinctly
conceives that the origin of his idea of
God can only be God Himself, i.e. the
only thing that can generate within
Descartes the idea of a perfect being is
a perfect being.
• Since, therefore, Descartes possess an
idea of God, God must, and does, exist.
• Anticipating an objection Ludwig Feuerbach
would raise 200 years later, Descartes says:
– “Nor should I imagine I perceive the
infinite . . . only by the negation of the
finite, just as I perceive repose and
darkness by the negation of movement and
light . . . . For, how would it be possible that
I should know . . . that something is lacking
[in] me, and that I am not quite perfect,
unless I had within me some idea of a
Being more perfect than myself, in
comparison with which I should recognize
[my] deficiencies.”
Meditations on First Philosophy
– Descartes’ idea of God cannot be
merely a projection and magnification
of his own nature.
– Descartes claims he would not be
able to recognize his own
imperfections, unless he had a prior
idea of perfection by which to judge
himself deficient.
– Amadeus
The Deduction of Matter
• God has placed in humans the strong
desire to believe in the existence of
material objects they clearly and
distinctly perceive.
• If God has placed this desire in humans
and their clear and distinction
perceptions are delusory, then God is a
tease and a deceiver.
• Since God is perfectly good, He cannot
be a tease and a deceiver.
• Thus, humans’ clear and distinct
perceptions are veridical, and the
material objects they clearly and
distinctly perceive really do exist.
Critique of Descartes
• The Cartesian Circle
– Descartes first appeals to the clear
and distinct standard to prove God,
then he appeals to God to prove the
clear and distinct standard.
– Response: There are two clear and
distinct standards – one for
conceiving and the other for
perceiving.
– Descartes uses the intuition of his
mind to establish the first standard,
and he makes God the guarantor of
the second.
• Recognizing imperfection
– Does Descartes really need an idea
of perfection to realize he is
imperfect?
• No.
– Wouldn’t, at most, Descartes only
need an idea of the better?
• Yes.
– Can’t Descartes conceive of the
better by magnifying his own
qualities?
• Yes.
– If Descartes were to claim that he
had an actual experience of
perfection, like Salieri’s experience
upon encountering Mozart’s music,
then, perhaps, he could argue only a
perfect being could cause such an
experience.