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PHIL 151 History of Modern Philosophy

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Title: PHIL 151 History of Modern Philosophy


1
PHIL 151 History of Modern Philosophy
  • Dr. Martin Godwyn
  • Fall 2008
  • WEEK 3 Descartes Ontology

2
Why prove the existence of God?
  • Why does Descartes need to prove the existence of
    God?
  • Having admitted that his senses and (perhaps)
    even elementary logical operations can be
    deceived by an evil demon, he needs a benevolent
    God to ensure that he is not systematically
    deceived in his reasoning or (ultimately) by his
    senses.
  • Thus, he needs to prove that what he clearly and
    distinctly conceives by the natural light of
    reason will be reliable.

3
Why prove the existence of God?
  • In the Fourth Meditation, Descartes argues that a
    benevolent God, would not allow him to be without
    at least the capability of distinguishing
    knowledge from erroneous belief, because this
    would require God to be deceitful, which
    contradicts the concept of God.
  • Thus, since he clearly and distinctly conceives
    that God must exist, he knows that when guided by
    the light of reason he will not be led
    systematically astray.

4
The Cartesian Circle
  • Here critics say Descartes reasoning is
    circular.
  • It is by application of the natural light of
    reason that he has been guided to make various
    arguments and claims, including an argument for
    the existence of a benevolent God who would not
    allow him to be systematically deceived. This
    conclusion, by means of the argument, he clearly
    and distinctly sees to be true.

5
The Cartesian Circle
  • But it is precisely in order to prove that what
    he clearly and distinctly sees to be true must be
    true, that he needs to prove Gods existence.
    Otherwise, the evil demon might be leading him
    astray in (amongst other things) his proof of
    God. This is often called the Cartesian Circle.
  • Can Descartes escape this circle?
  • Ask yourself this what is it for a belief to be
    unshakable or certain?

6
Certainty normative or psychological?
  • A key issue here is whether, regarding the claim
    that anything clearly and distinctly conceived of
    as being true must be true, the third meditation
    argument is intended to establish that
  • a) we ought to believe it, or
  • b) as a matter of psychological necessity, we
    cannot help but believe it.

7
Why do we err?
  • Another immediate problem (also dealt with in the
    Fourth Meditation) is that his arguments might
    prove too much.
  • Clearly, we sometimes are mistaken. But how can
    this happen, given that there exists a
    non-deceiving God who would not allow us to be
    systematically mislead?

8
Why do we err?
  • It must be simply this the scope of the will is
    wider than that of the intellect but instead of
    restricting it within the same limits, I extend
    its use to matters which I do not understand.
    Since the will is indifferent in such cases, it
    easily turns aside from what it true and good,
    and this is the source of my error and sin.
    (21)...
  • If I restrain my will so that it extends to
    what the intellect clearly and distinctly
    reveals, and no further, then it is quite
    impossible for me to go wrong. (22)

9
Why do we err?
  • Descartes response hinges on our wilful nature.
    We are gifted with free will, and we sometimes go
    beyond the boundaries of what reason and evidence
    can justify to believe things for which we have
    inadequate grounds. Thats when we make mistakes,
    argues Descartes.
  • In short, God does not deceive us, we deceive
    ourselves by not restraining our will (with
    respect to belief) within the bounds of the
    intellect.

10
Another proof of God
  • The primary goal of the Fifth Meditation, is to
    offer another proof of God.
  • What Descartes offers in the Fifth Meditation is
    a crisper version of what came to be called the
    ontological proof of God, more famously
    attributed to St. Anselm.

11
God as necessary-existence
  • Roughly, the argument goes like this
  • 1. God is a supremely perfect being.
  • 2. Existence is a perfection.
  • 3. Therefore, existence cannot be separated from
    concept of God i.e., it is a contradiction to
    suppose a supremely perfect being without it
    existing, since to not exist would be to lack a
    perfection.
  • 4. Any property that cannot be separated from
    something is necessarily a property of such an
    object.
  • 5. Therefore, God necessarily exists.

12
God is a supremely perfect being
  • Descartes claims, as we know, to have this
    concept of God innately. But here the source of
    the concept does not matter very much for this
    proof.
  • What matters, firstly, is that the concept of a
    supremely perfect being is logically coherent and
    hence is a logical possibility.
  • (Note Descartes insists that God cannot do the
    logically impossible. So he avoids old chestnuts
    such as Can God make a stone so heavy even he
    cant lift it? answering either way seems to
    limit Gods powers.)

13
Existence as a perfection
  • The claim that existence is a perfection is
    perhaps the most critical premise.
  • The underlying motivation for this seems to be
    that in some metaphysically significant sense,
    something will be a greater or more perfect thing
    if it is a real thing as well as an idea rather
    than just an idea.
  • Is this an intuitively sound principle?

14
Necessary existence
  • It is important to note that Descartes thinks
    that the ontological argument shows that God does
    not merely exist, but necessarily exists.
  • For Descartes, Gods existence is a matter of
    logical necessity flowing from the concept of
    God, just as much as having internal angles
    adding to two right angles is a necessary feature
    of triangles.
  • (The mathematician, Kurt Gödel, even developed a
    formal mathematical proof of Gods existence
    based on this argument.)

15
The necessity of God
  • It is quite evident that existence can no more
    be separated from the essence of God than the
    fact that its three angles equal two right angles
    can be separated from the essence of a triangle,
    or than the idea of a mountain can be separated
    from the idea of a valley. Hence it is just as
    much of a contradiction to think of God (that is,
    a supremely perfect being) lacking existence
    (that is, lacking a perfection), as it is to
    think of a mountain without a valley. (24)

16
Criticisms
  • There are a number of criticisms of the
    ontological proof for God.
  • 1. You cant define things into existence.
  • Descartes agrees, but responds that the internal
    angles of a triangle adding to two right angles
    is not a matter of mere definition its a
    logical necessity. We dont define triangles
    having those internal angles, its just a
    necessary truth about them. And the existence of
    God is just like that a necessary property of
    God.

17
Is existence a property?
  • 2. Existence is not a property attributable to
    things.
  • Kant argues that existence is not, properly
    speaking, a property of things in the relevant
    sense, hence not a perfection.
  • Existence is more like a precondition for the
    possibility of something having properties at all.

18
Sixth Meditation
  • In the Sixth Meditation Descartes applies his
    results to show that
  • 1. material bodies exist out in an external
    world, and
  • 2. there are two basic and mutually exclusive
    kinds of stuff in the universe mind and body.

19
The external world
  • Descartes argues that sensation can only give me,
    at best, a probabilistic justification for the
    existence of an external world.
  • Using the example of a thousand-sided figure, he
    notes that perception and our faculty of the
    imagination that utilises it, is often confused
    and indistinct. By contrast, the conception of a
    thousand-sided figure is as clear and distinct
    for a thousand-sided as for a pentagon.

20
The external world
  • Using his faculty of understanding, he then
    argues that
  • God has given me no faculty at all for
    recognising any such source for these
    perceptual ideas on the contrary, he has given
    me a great propensity to believe that they are
    produced by corporeal things. So I do not see how
    God could be understood to be anything but a
    deceiver if the ideas were transmitted by a
    source other than corporeal things. It follows
    that corporeal things exist. (29)

21
Mind and Body
  • Descartes arguments also lead him to conclude
    that there is an essential metaphysical
    distinction between the mind and the body.
  • This view Cartesian Dualism claims that there
    are two fundamentally distinct kinds of stuff in
    the universe matter and mind.
  • Cartesian Dualism, and the challenges it faces,
    generates a great deal of philosophical enquiry
    through to the present day.

22
Physicalism
  • Cartesian Dualism can be contrasted with a number
    of other positions
  • Physicalism (materialism) The view that the only
    substance that exists fundamentally is matter or
    physical stuff. The mental is nothing over and
    above the physical.
  • Not a very popular view until the 19th and 20th
    century. (Although Thomas Hobbes, a contemporary
    of Descartes, was an early advocate).

23
Idealism
  • Idealism The view that the only thing that
    exists is mental stuff minds and the ideas they
    contain. Matter and all things physical is
    nothing over and above the mental. Berkeley is
    the chief advocate of this view.
  • Both idealism and physicalism are monisms they
    claim that there is just one basic kind of stuff
    in the universe.

24
Neutral Monism
  • Some monisms deny that that all that exists is
    one of those two kinds. Instead, they suggest
    that mind and matter is really just two
    attributes (or ways of being) of a single
    substance.
  • The physical and the mental are not kinds of
    stuff, on this view, but rather ways that stuff
    has of being or presenting itself to us. This
    view is often called neutral monism, and is
    represented by Spinoza.

25
Why dualism?
  • Descartes argues that mind (i.e., I, the self,
    the soul) and matter (i.e., material body or
    corporeal stuff) must be different kinds of
    substance.
  • He presents two closely related arguments for
    this view that flow into each other
  • 1. The argument from conceivable separation I
    can conceive of the (mind) without (body).
  • 2. The argument from essential properties what
    is essential to each is the contradictory of what
    is essential to the other.

26
The argument from conceivable separation
  • The argument from conceivable separation draws on
    a key result of his skeptical arguments in the
    first two meditations.
  • The fact that I can clearly understand one thing
    apart from another is enough to make me certain
    that the two things are distinct, since they are
    capable of being separated, at least by God. (28)

27
The argument from conceivable separation
  • In essence, the argument seems to be this
  • 1. I can conceive of mind existing without body
    and body without mind.
  • 2. Whatever can be separated in conception is
    (essentially) distinct.
  • 3. Therefore, mind and body are (essentially)
    distinct substances.
  • What do you think of this argument?

28
The argument from essential properties
  • 1) The mind is essentially a thinking thing. (In
    other words, thinking, which includes doubting,
    imagining, believing etc., is the essential
    property of minds. Anything that thinks is a
    mind, and anything that is a mind, thinks.)
  • Simply by knowing that I exist and seeing at
    the same time that absolutely nothing else
    belongs to my nature or essence except that I am
    a thinking thing, I can infer correctly that my
    essence consists solely in the fact that I am a
    thinking thing. ... (28)

29
The argument from essential properties
  • 2) It is inconceivable that a thinking thing be
    divided into two. Minds are necessarily
    indivisible. (Consider what is half a thought
    or half a mind? Descartes argues that this is
    incoherent.)
  • 3) For any spatially extended thing, it is
    conceivable that it be divided into two. I.e.,
    spatially extended things are necessarily
    divisible, at least in principle.
  • 4) Therefore, minds cannot be spatially extended.

30
The argument from essential properties
  • 5) A body is essentially a spatially extended
    thing. (From the ball of wax argument anything
    that is a body has spatial extension, and
    anything spatially extended is a body.)
  • 6) Therefore, since minds and bodies have
    essential properties that are inconsistent with
    each other (respectively non-extension and
    extension), minds cannot be bodies, and bodies
    cannot be minds.

31
The argument from essential properties
  • It is true that I may have ... a body that is
    very closely joined to me. But nevertheless, on
    the one hand I have a clear and distinct idea of
    myself, in so far as I am simply a thinking,
    non-extended thing and on the other hand I have
    a distinct idea of body in so far as this is
    simply an extended, non-thinking thing. And
    accordingly, it is certain that I am really
    distinct from my body, and can exist without it.
    (28)
  • Do you agree?

32
The attractiveness of dualism
  • Dualism did not start with Descartes. Dualism was
    a background assumption of most Western thinkers
    prior to Descartes and remains a popular and
    perhaps intuitive position even today.
  • But Descartes helped to bring to a focus the deep
    problems that underlie our intuitive notions of a
    world of mind and matter as fundamentally
    different kinds of stuff.

33
Explaining interaction
  • The central problem that Descartes faced by
    adopting dualism was how to explain the apparent
    interaction between mind and matter. For example
  • Someone stabs a fork into my leg (a physical
    event) apparently causes me to feel pain (a
    mental event).
  • Me thinking of sucking lemons (a mental event)
    apparently causes my mouth to salivate (a
    physical event).

34
Descartes view
  • Nature also teaches me, by these sensations of
    pain, hunger, thirst and so on, that I am not
    merely present in my body, as a sailor is present
    in a ship, but that I am very closely joined and,
    as it were, intermingled with it, so that I and
    the body form a unit. If this were not so, I, who
    am nothing but a thinking thing, would not feel
    pain when the body was hurt, but would perceive
    the damage purely by the intellect, just as the
    sailor perceives by sight if anything in his ship
    is broken. (29)

35
The mind-body problem
  • But even intermingled stuff needs to interact to
    explain apparent mind-body interaction.
    Descartes best guess was that the interaction
    took place in the pineal gland (at the base of
    the brain), but where it happens is not the real
    philosophical issue how can something extended
    or material possibly interact with something
    non-extended and non-material?
  • This problem how the mental and the physical
    interact or are metaphysically related is
    usually known as the mind-body problem.
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