A.
Argument from Conceivability
P1: I
can conceive of me existing without my body.
C1: So
it is possible that I exist but my body doesn’t.
P2: If
a = b, then necessarily a = b.
C2: So
I am not identical to my body.
B.
Argument from Essences
P1: I
am (only) essentially a thinking thing.
P2: My
body is (only) essentially an extended thing.
P3: If
a = b, then they have the same essence.
C: I am not identical
to my body.
C. Argument
from Doubt
P1: I can doubt that my body exists.
P2: I cannot doubt that I exist.
C1: So
my body has a property that I do not have.
P4: Leibniz’s
Law: If a = b, then a and b have all the same properties.
C2: So
I am not identical to my body.
P1: Lois can doubt that Superman is Clark Kent.
P2: Lois
cannot doubt that Clark Kent is Clark Kent.
C1: So
Superman has a property that Clark Kent does not have.
P4: Leibniz’s
Law: If a = b, then a and b have all the same properties.
C2: So
Superman is not identical to Clark Kent.
P1: If
dualism is correct, then mind and body are radically different substances.
P2: Radically different substances cannot
causally interact.
2a: Causal
interaction requires something like contact in a common medium.
2b: Radically
different substances cannot come into contact with one another in a common
medium.
P3: Mind and body do causally interact.
3a: Perception:
Physical states (opening eyes in a well-lit room) cause mental states (visual
sensations).
3b: Intentional
Action: Mental states (beliefs and desires) cause physical states (bodily
movements).
C: So dualism is not correct.
P1: There
is something it is like to be in certain conscious mental states (e.g., having
a visual sensation of red)—certain mental states have a qualitative feel.
P2: What
it is like to be in certain mental states is not determined by the totality of
relevant physical facts.
C: So the qualitative feel
of mental states is not a physical property.