Ren

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René Descartes(1596-1650 AD)

• Meditations on First Philosophy
• (1641)

(Text, pp. 87-119)
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(No Transcript)
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Descartes Problem
Background

• The problem of skepticism (D concentrates on 2
  types of skepticism)
• General skepticism There are NO indubitable
  beliefs or propositions.
• Skepticism concerning the existence nature of
  the external world The existence and nature
  of the external world cannot be known.

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The overall structure of Ds Meditations(next
slide)
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General Cogito (existence of the I) (Med.
I) (Med. II) Mind-Body
Dualism Skepticism God (no
deceiver) External 1. My idea of God
(III) World 2. My contingent (Meds.
III-VI) existence (III)
3. The ontological argument
(again) (V)
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Meditation I

• Radical (General) Skepticism

(Text, pp. 87-92)
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Descartes Foundationalism
(See Text, 87-8)
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Ds program of radical doubt

• Treat any belief that is to the slightest extent
  uncertain subject to doubt just as though it is
  obviously false.
• Accept only those beliefs that are completely
  certain and indubitable.
• Work on the foundations of my beliefs.

(Text, 88)
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Foundational Beliefs

• Empiricism True beliefs are acquired through
  sense experience (89).
• My beliefs are not products of insanity (89).
• My beliefs are not products of my dreams (89-90).

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Foundational Beliefs, contd

• Physical objects Even if we fail to perceive
  physical objects accurately, the primary
  measurable qualities of such objects (matter,
  extension, shape, quantity, size, location, time,
  etc.) are really real (i.e., physical objects do
  really exist) (90-91).
• Even if empirical beliefs are subject to doubt,
  mathematical propositions are indubitable (e.g.,
  3 2 5, a square has neither more nor less
  than four sides) (91).

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Extra-Credit Essay (250 words)

• How does Descartes challenge each of the
  foregoing foundational beliefs?
• How does he use the ideas of God and the Devil in
  building his case in support of radical
  skepticism?

(Text, 91-92)
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Meditation II

• Descartes Refutation of Radical Skepticism

(Text, pp. 93-97)
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Descartes refutation ofradical skepticism

• Cogito ergo sum!

What does this mean?
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The most famous statement in the history of
philosophy

• I think therefore I am.

Discourse on Method (1637)
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If I am deceived,then I must exist!
I cannot doubt the truth of the statement, I
exist.
(Why not?)
(Text, 93-94)
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Thus,

• Radical (general) skepticism is refuted.

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Meditation II, contd

• The Mind-Body Problem
• Descartes Psycho-Somatic Dualism

(Text, 94-97)
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Three metaphysical perspectives relevant to the
mind-body problem
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Metaphysical Dualism Reality is
two-dimensional, partly material and partly
non-material (minds, ideas, souls, spirits,
consciousness, etc.). Metaphysical Materialism
Reality is nothing but matter-in-motion-in-space-a
nd-in-time. There are no non-material
realities. Metaphysical Idealism Reality is
nothing but Mind, Idea, Soul, Spirit,
Consciousness, etc. Matter does not exist (its
an illusion?).
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Application to the mind-body problem

• Metaphysical Materialism A person is nothing
  but a physical organism (body only).
• Metaphysical Idealism A person is
  consciousness only (mind, soul, spirit) not at
  all a material being.
• Metaphysical Dualism A person is a composite of
  (1) mind (consciousness, soul, spirit) and
  (2) body.

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Cartesian Dualism

• I know with certainty THAT I exist (Cogito ergo
  sum), but
• WHAT am I?
• Am I my body? No, because I can doubt the
  existence of my body, whereas I cannot doubt the
  existence of myself (the I).
• I am a thinking thing, a thing that doubts,
  understands, affirms, denies, wills, refuses,
  imagines, and has sensations.

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Is Descartes right?

• Can you doubt the existence of your body (as well
  as other physical things)?

Why or why not?
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I can conceive of myself as existing without a
body, but I cannot conceive of myself as existing
without conscious awareness.

• Bryan Magee, The Great Philosophers (Oxford 1987)

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In Descartes view,

• my body exists (if it exists at all) outside of
  my consciousness and is therefore part of the
  external world.

Thus,
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Descartes mind-body dualism leads to . . . .
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Meditation III,which deals with

• (1) skepticism concerning the existence nature
  of the external world
• (2) the existence of God

(Text, pp. 97-110)
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I must, as soon as possible, try to determine
(1) whether or not God exists and (2) whether or
not He can be a deceiver. Until I know these two
things, I will never be certain of anything else
(Text, 99).

• Why does Descartes say this?

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Descartes standard of certainty

• What does it take for a belief to be certainly
  (indubitably) true?
• The belief must be clear and distinct.
• Descartes general rule Everything that I can
  clearly and distinctly grasp is true.

(Text, 98)
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Are the following beliefsclear
distinct(indubitable)?

• That there are things outside myself (such as
  physical objects).
• That these external things cause my ideas of
  those things in my mind.
• That my ideas of external things perfectly
  resemble the things themselves.
• That 3 2 5 ?

(Text, 98-99)
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Reasons for believing (1) that there are things
outside myself (2) which cause my ideas of those
things in my mind and (3) that my ideas of
external things resemble (accurately represent)
the things themselves
The epistemology represented by (1), (2), (3)
is known as Common Sense Realism or
Representationalism.
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• I have a strong natural inclination to believe
  these things.
• My ideas of external things arise in my mind
  independently of my will.
• It seems obvious that external objects impress
  their own likenesses upon my senses.

(Do these reasons clearly distinctly prove
that Common Sense Realism is true?) (See 100)
(Text, 99-100)
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Ideas their causes(Text, 101-105)
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When I think of an entity, I can distinguish
between . . . .

• Substance (i.e., the entity itself, e.g., an
  automobile tire),
• Modes (i.e., the ways in which the entity exists,
  e.g., the tire may be flat ), and
• Accidents (i.e., the properties, qualities, or
  attributes of the entity, e.g., the color of the
  tire blackness? ).

And isnt it obvious that substance is more real
than mode or accident?
(Text, 101)
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Ideas of things (substances, modes, accidents)

• must be caused to be in the mind, and

the cause of any effect must be sufficient to
produce its effect, i.e.,
there must be at least as much reality in a cause
as is represented in its effect.
(Text, 101-103)
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Descartes thinks of ideas as

• But is this last point true? Suppose I perceive
  an automobile with a dented fender , from my
  perception, an idea of the car arises in my mind.
  Why cant I think of the car as NOT having a
  dented fender?
• How might Descartes respond to this criticism?

• subjective representations of the realities that
  cause them to be in the mind (102).
• He also believes that ideas cannot represent more
  reality (anything greater or more perfect) than
  is in the things the ideas represent (102-3).

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If one of my ideas
(Text, 103)

• has something in it that is not within myself,
  then
• I could not be the cause of that idea whereas
• if I could be the cause of all of my ideas, then
• I will have no foolproof reason to believe that
  anything exists other than myself.

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Ideas in my mind
(Text, 103)

• of myself (could be caused by myself)
• of God
• of lifeless physical objects
• of angels
• of animals
• of other people

Could be composed from my ideas of myself,
physical objects, and God (how?)
What about physical objects?
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The qualities of physical objects

• Primary qualities size, length, breadth, depth,
  shape, position, motion, substance, duration,
  number, etc.
• Secondary qualities light, color, sound, odor,
  taste, heat, cold, etc.

(Text, 103-104)
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Since my ideas of the secondary qualities of
physical objects

• are not clear and distinct,
• and since such qualities are almost
  indistinguishable from nothing (i.e, they seem to
  represent very little reality),
• I myself a substance could be the author of
  such ideas.

(Text, 104)
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I could also be the cause of my ideas of primary
qualities.
(Text, 104-105)

• I am a substance.
• I have duration in that I exist now and have
  existed for some time.
• I can count my several thoughts and thus the idea
  of number may be grounded in my thought process.
• But what about my ideas of extension, shape,
  position, and motion?

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Although extension, shape, position, or motion do
not exist in me (since I am not a physical
being),

• these are only modes of existence, and, as a
  substance,

I have more reality than these modes and I
am therefore sufficient to cause my ideas of them.
(Text, 105)
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Thus,

• I could be the cause of my ideas of both the
  primary and secondary qualities

of physical objects.
However,
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I do not have what it takes

• to produce the idea of God (an infinite substance)

from within myself (a finite substance).
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Descartes first argument

• for the existence of God . . . .

(Text, 105-107)
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By God, I mean

• an infinite and independent SUBSTANCE,
  all-knowing and all-powerful, who created me and
  everything else . . . . (Text, 105)

This idea represents more reality than there is
in myself (since I am finite, limited in
knowledge power, etc.). Thus, the idea of God
must be caused to be in my mind by something
other than myself. And . . . .
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since there must be at least as much reality in a
cause as there is in its effect(s),

• it follows necessarily that my idea of God must
  be caused by God Himself and if God is the cause
  of my idea of God, then

God must exist!
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Descartes main point here is

• that I could not be the cause of the idea of God
  that I find in my mind
• since God is a being more perfect than myself.

• How could I, merely from within myself, form the
  idea of a being more perfect than myself?
• Then my idea would represent more reality than
  there is in its cause.

Only God is a sufficient cause of the idea of God
in my mind.
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Descartes second argumentfor the existence of
God . . . .
(Text, 108-110)
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I exist as a thinking thingwith the idea of God
(an infinitely perfect being) in my mind,

• but my existence is not necessary -- it is
  contingent -- which means

that I must be caused to exist (at every moment
of my existence) by something other than myself
(108-9).
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If the cause of my existence

• is itself a contingent being (e.g., my parents or
  something else less perfect than God), then
• it must also be caused to exist by something
  other than itself. But . . . .
• this cause-and-effect process cannot go on to
  infinity since in that case
• I could never begin to exist.
• So . . . .

(See Text, 109)
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there must be a First Cause

• whose existence is necessary (rather than
  contingent).

Furthermore . . . ,
(Text, 109)
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this necessarily existing First Cause,

• which is the ultimate cause of my existence,
• must have the idea of God in it, and
• since it is a First Cause, its idea of God must
  be caused by itself and nothing else, which means
• that this First Cause must be God (since only God
  can be the original cause of the idea of God in
  any mind).

(Text, 109)
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Why does Descartes reject the claim that

• his existence as a contingent being with the idea
  of God in its mind might be the effect of several
  natural causes, each representing a different
  kind of perfection?

Extra-Credit Essay (250 words)
(See Text, 109-110)
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Conclusion of the 3rd Meditation
(Text, 110)
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The idea that God cannot be a deceiver

• leads to

Meditation IV On the Problem of Error
Free will intellectual error
(See Text, 111)
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God the removal of doubt as to
Meditations V VI

• the existence of the external world

(Text, 112-119)
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The content of Meditation V

• Mathematical thinking its (physical
  non-physical) objects clarity distinctness
  again -- what is clear distinct must be true
  (112-113)
• Ds ontological argument for the existence of
  God (115-116)
• God certainty (116-118)

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Descartes third argument

• for the existence of God

(the ontological argument again)
(Text, 113-116)
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1. If the nonexistence of God (an infinitely
perfect being) were possible, then existence
would not be part of Gods essence (that is,
existence would not be a property of the
divine nature). 2. If existence were not part of
Gods essence (that is, a property of the
divine nature), then God would be a
contingent (rather than necessary) being. 3. The
idea of God as a contingent being (that is, the
idea of an infinitely perfect being with
contingent rather than necessary existence)
is self-contradictory. 4. It is impossible to
think of God as not existing. 5. The
nonexistence of God is impossible.
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Certainty about God

• is the basis of certainty about everything else.

(See Text, 116-117)
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Meditation VIRemoval of doubt as to the
existence of the external world

• Since God exists
• is no deceiver,
• it follows necessarily
• that the external world can be known to exist.

Why?
(See Text, 118-119)