Descartes on the Existence of the
Soul
Substance
Dualism
The mind and body are distinct
properties:
Matter is res extensa (Latin for
extended thing)
Mind is res cognita (Latin for mental substance)
Second
First Proof Third Proof
Proof
Argument Argument Argument
from Doubt from from Clear
Divisibility and Distinct
- When we doubt,
we cannot doubt and Non Perception
that we doubt Divisibility - A clear idea is one
that is immediately
- I think therefore I - Bodies are divisible, rationally intuited. A
am – cogito ergo minds are distinct idea is one
indivisible, that cannot be
sum – Foundation
therefore the mind mistaken for any
of argument is not the body. other idea.
- Evidence for - All qualia (states of - I have a clear and
dualism, if you distinct idea of
mind) are
myself as a non-
can doubt that indivisible extended thinking
the body exist thing. I have a clear
but can’t doubt - Derived from and distinct idea of
Leibniz my body as an
that the mind
‘Indiscernibility of extended non-
exists then they Identicals’ - if two thinking thing.
must be things look the
separate same they should - So I and my body
be treated as being can exist apart from
same, the each other.
discernability of the
- So I am distinct
mind and body from my body.
shows that they are
separate
Soul
Substance
Dualism
The mind and body are distinct
properties:
Matter is res extensa (Latin for
extended thing)
Mind is res cognita (Latin for mental substance)
Second
First Proof Third Proof
Proof
Argument Argument Argument
from Doubt from from Clear
Divisibility and Distinct
- When we doubt,
we cannot doubt and Non Perception
that we doubt Divisibility - A clear idea is one
that is immediately
- I think therefore I - Bodies are divisible, rationally intuited. A
am – cogito ergo minds are distinct idea is one
indivisible, that cannot be
sum – Foundation
therefore the mind mistaken for any
of argument is not the body. other idea.
- Evidence for - All qualia (states of - I have a clear and
dualism, if you distinct idea of
mind) are
myself as a non-
can doubt that indivisible extended thinking
the body exist thing. I have a clear
but can’t doubt - Derived from and distinct idea of
Leibniz my body as an
that the mind
‘Indiscernibility of extended non-
exists then they Identicals’ - if two thinking thing.
must be things look the
separate same they should - So I and my body
be treated as being can exist apart from
same, the each other.
discernability of the
- So I am distinct
mind and body from my body.
shows that they are
separate
