Michael Lacewing enquiriesalevelphilosophycouk c Michael Lacewing Substance dualism Substance dualism there are two sorts of substance mind or soul and matter Minds are distinct from bodies ID: 642784
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Slide1
Descartes’ conceivability argument for substance dualism
Michael Lacewingenquiries@alevelphilosophy.co.uk
(c) Michael LacewingSlide2
Substance dualism
Substance dualism: there are two sorts of substance, mind (or soul) and matter
Minds
are distinct from bodies
Minds are not properties of bodiesMental properties are properties of a mental substanceCartesian substance dualism: minds can exist independent of bodies
(c) Michael LacewingSlide3
Descartes’ conceivability argument
I have a clear and distinct idea of myself as something that thinks and isn’t extended.I have a clear and distinct idea of body as something that is extended and does not think.
Nothing in our concepts rules out the possibility that mind and body are distinct.
(c) Michael LacewingSlide4
Descartes’ conceivability argument
If I have a clear and distinct thought of something, God can create it in a way that corresponds to my thought.If God is omnipotent, God can make anything that is not self-contradictory. The concepts of mind and body are not self-contradictory.
Therefore, God can create mind as something that thinks and isn’t extended and body as extended and does not think.
It is important that our concepts of mind and body are complete and exclusive. This is shown by their being clear and distinct.
(c) Michael LacewingSlide5
Descartes’ conceivability argument
Therefore, mind and body can exist independently of one another.A substance is something that can exist independently.Therefore, mind and body are two distinct substances.
(c) Michael LacewingSlide6
The simple version
It is conceivable that mind can exist without body.Therefore, it is possible that mind can exist without body.Therefore, mind and body are distinct substances.
(c) Michael LacewingSlide7
Is mind without body
conceivable?Can we really conceive of mind without body?
What is thinking, really?
Perhaps we become confused when conceiving of mind as distinct from the body
Philosophical behaviourism: To talk of mental states is to talk of how something behavesBut without a body, how can something exhibit behaviour
?
A mental state is something that only a physical substance can have
Is this right? It makes God inconceivable…Slide8
What is conceivable may not be metaphysically possible
Just because Descartes can
think
of his mind existing without his body, this doesn’t mean that his mind
really can exist without his body.
Physical possibility: what is
possible given the laws of nature as they are in the actual
world
Logical possibility: what
is not self-contradictory, what our concepts allow
It is logically possible that the laws of nature were different
Metaphysical possibility: what is necessarily, but not analytically, true; constrained by
identity and nature of things
Water is
H
2
O
– given that it is, nothing could be water but not
H
2
OSlide9
Conceivability and possibility
What is conceivable is not always possibleIt is conceivable that water is not
H
2
O, but it is not metaphysically possibleThe Masked Man fallacyI think the Masked Man robbed the bank; I don’t think my father robbed the bank; Therefore, my father isn’t the Masked Man.
In one sense, it is possible that my father is not the Masked Man
. (I can certainly conceive this.)
But if, unknown to me, my father
is
the Masked Man, then it is impossible that my father is not the Masked Man
(c) Michael LacewingSlide10
Conceivability and possibility
From conceiving that ‘two’ people are distinct, we can’t infer that they are distinct.
Perhaps this applies to mind and
body
Descartes’ reply: when we clearly and distinctly conceive of two things as distinct, then we
can
infer that they are distinct
Clear and distinct conception can establish possibility, e.g. all triangles must have angles that add up to
180°
Masked Man: not clear and distinct; mind and body: clear and distinctSlide11
Possibility and reality
Suppose it is possible that the mind can exist as a distinct substance. Does this show that it is a distinct substance?
If we can conceive of the mind and body as
not
distinct, e.g. that the mind is the thinking part of something extended, then it also seems possible that the mind is not a substanceSo which is it?Descartes must show not only that it is possible for the mind to be independent of the body, but that it is impossible for it to be dependent on the body