René Descartes _1596-1650 AD_

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					René Descartes
(1596-1650 AD)

         Meditations on First Philosophy

                           (Text, pp. 87-119)

             Descartes’ Problem
      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
The overall structure of D’s
       (next slide)
             General          Cogito (existence of the “I”)
             (Med. I)                                     (Med. II)
                                     Mind-Body Dualism
                                              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)
             Meditation I

Radical (General) Skepticism

                               (Text, pp. 87-92)
Descartes’ “Foundationalism”
 Epistemological Foundations & Superstructure

                 (also false?)

    False           False            False
 Foundational    Foundational     Foundational
    Belief          Belief           Belief

                                        (See Text, 87-8)
D’s 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)
          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).
    Foundational Beliefs, cont’d
   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).
   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)
                Meditation II

Descartes’ Refutation of Radical Skepticism

                                  (Text, pp. 93-97)
    Descartes’ refutation of
      radical skepticism

“Cogito ergo sum!”

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

“I think; therefore I am.”

           Discourse on Method (1637)
                “If I am deceived,

            then I must exist!”

                      I cannot doubt the truth of
                      the statement, “I exist.”

(Text, 93-94)

Radical (general) skepticism is refuted.
          Meditation II, cont’d

   The Mind-Body Problem &
Descartes’ Psycho-Somatic Dualism

                                (Text, 94-97)
    Three metaphysical
perspectives relevant to the
   “mind-body problem”
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-and-in-time.
There are no non-material realities.

Metaphysical Idealism: Reality is nothing
but Mind, Idea, Soul, Spirit, Consciousness,
etc. Matter does not exist (it’s an illusion?).
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.
        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.
          Is Descartes right?

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

              Why or why not?
“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)
          In Descartes’ view,

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

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

(1) skepticism concerning the
  existence & nature of the
       “external world”
   (2) the existence of God
                            (Text, pp. 97-110)
“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?
    Descartes’ standard of
 What   does it take for a belief to be
  certainly (indubitably) true?
 The belief must be “clear and
 Descartes’ general rule: “Everything
  that I can clearly and distinctly grasp
  is true.”
                                  (Text, 98)
    Are the following beliefs
        “clear & distinct”
 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)
 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

                 *The epistemology represented by
                 (1), (2), & (3) is known as
                 “Common Sense Realism” or
•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
             (Do these reasons “clearly &
             distinctly” prove that Common
             Sense Realism is true?) (See 100)
Ideas & their causes
      (Text, 101-105)
     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 isn’t it obvious that substance
(Text, 101)             is more real than mode or accident?
            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)
        Descartes thinks of ideas as
                                        But is this last point true?
   subjective representations of        Suppose I perceive an
    the realities that cause them        automobile with a dented
    to be in the mind (102).             fender &, from my
                                         perception, an idea of the
   He also believes that ideas
                                         car arises in my mind.
    cannot represent more reality        Why can’t I think of the
    (anything greater or more            car as NOT having a
    perfect) than is in the things       dented fender?
    the ideas represent (102-3).        How might Descartes
                                         respond to this criticism?
                                     (Text, 103)
If one of my ideas
  has something in it that is not within myself,
  I could not be the cause of that idea;
  if I could be the cause of all of my ideas,
  I will have no foolproof reason to believe
   that anything exists other than myself.
                                           (Text, 103)

          Ideas in my mind:
 of myself (could be caused by myself)
 of God
 of lifeless physical objects
 of angels
                          Could be composed from my
 of animals              ideas of myself, physical
                          objects, and God (how?)
 of other people

                     What about physical objects?
The qualities of physical objects:

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

                                (Text, 103-104)
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)
    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
 But what about my ideas of extension, shape,
  position, and motion?
  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)

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

           of physical objects.
     I do not have what it takes

to produce the idea of God
  (an infinite substance)

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

  for the existence of God . . . .

(Text, 105-107)
               “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 . . . .
     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!
Descartes’ main point here is
   that I could not be the        How could I, merely
    cause of the idea of            from within myself,
    God that I find in my           form the idea of a
    mind                            being more perfect
   since God is a being            than myself?
    more perfect than              Then my idea would
    myself.                         represent more reality
                                    than there is in its

                              Only God is a sufficient cause
                              of the idea of God in my mind.
 Descartes’ second argument

 for the existence of God . . . .

(Text, 108-110)
      I exist as a thinking thing
  with 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).
    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
                                       (See Text, 109)
 I could never begin to exist.
 So . . . .
         there must be a First Cause

  whose existence is necessary (rather
          than contingent).

                          Furthermore . . . ,
(Text, 109)
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)
      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?

                             (See Text, 109-110)
Conclusion of the 3rd Meditation

 From the simple fact that I exist and that I have in my
 mind the idea of a supremely perfect being, that is,
 God, it necessarily follows that God exists . . . . The
 whole argument rests on my realization that it would
 be impossible for me to exist as I do -- namely, with
 the idea of God in my mind -- if God didn’t exist. It
 also follows that [since God is perfect] God cannot be
 a deceiver [because fraud and deception are caused by
 defects] . . . .
                                         (Text, 110)
   The idea that God cannot
         be a deceiver
leads to

                   (See Text, 111)
God & the removal of doubt as to

     the existence of the external world
                            (Text, 112-119)
The content of Meditation V
   Mathematical thinking & its (physical &
    non-physical) objects: clarity &
    distinctness again -- what is clear & distinct
    must be true (112-113)

   D’s “ontological” argument for the
    existence of God (115-116)

   God & certainty (116-118)
   Descartes’ third argument

for the existence of God

          (the ontological argument again)

                              (Text, 113-116)
1. If the nonexistence of God (an infinitely perfect
   being) were possible, then existence would not be
   part of God’s essence (that is, existence would not
   be a property of the divine nature).
2. If existence were not part of God’s 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.
       Certainty about God

is the basis of certainty about
        everything else.

                          (See Text, 116-117)
         Meditation VI
  Removal 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.
                        (See Text, 118-119)

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