Week 2, Lecture 3
Dualism: mental events, substance
vs. property dualism, four arguments
Mental Events
• An event = an object’s losing and/or acquiring
properties.
• A property = anything that can characterize an object,
e.g., greenness, sphericity, goodness, warmth, being
divisible by 2.
– Examples of events:
• Giving a hug – the two people’s relative locations and postures
change.
• A banana ripening – the peel loses the property of being green and
acquires the property of being yellow.
Mental events, cont.
• Examples of mental events:
– Coming to feel a pain – the person acquires the
property of being in a state of pain.
– Coming to have a belief – the person acquires the
property of having a belief.
Mental Events and Dualism
• The concept of an event allows us to
distinguish two versions of dualism:
– Substance dualism: there are both physical and
mental objects, or substances.
– Property dualism: there are both physical and
mental events.
The Argument from Introspection
1. We seem to have privileged access to facts about our own
minds in the sense that we can know about our own minds
in a direct and unique way; we can introspect our own
minds. (Premise)
2. When I introspect my belief state, I do not perceive any
shape, mass, etc. (Premise)
Therefore,
3. My mind, which is in the belief state, has no shape, or mass,
or…. (From 1,2)
4. If x has no shape, or mass, or…, then x is non-physical.
(Premise)
Therefore,
5. My mind is non-physical. (From 3,4)
Objection 1 to the Argument from
Introspection
1.
We seem to have privileged access to facts about our own minds
in the sense that we can know about our own minds in a direct
and unique way; we can introspect our own minds. (Premise)
2. When I introspect my belief state, I do not perceive any shape,
mass, etc. (Premise)
Therefore,
3. My mind, which is in the belief state, has no shape, or mass, or….
(From 1,2)
• Objection 1:
– The inference from 1,2 to 3 is invalid.
– Reason: We can know some things by introspection (e.g., I can
know that I am in pain). But introspection does not tell us the
metaphysical nature of our mental states.
Objection 2 to the Argument from
Introspection
1.
We seem to have privileged access to facts about our own minds in the
sense that we can know about our own minds in a direct and unique
way; we can introspect our own minds. (Premise)
2. When I introspect my belief state, I do not perceive any shape, mass, etc.
(Premise)
Therefore,
3. My mind, which is in the belief state, has no shape, or mass, or…. (From
1,2)
• Objection 2:
– The inference from 1,2 to 3 is invalid.
– Reason: My belief state is a mental property of something. From the
fact that there is a non-physical property, it does not follow that there
is a non-physical substance, i.e., a mind. Belief states could be nonphysical properties of physical substances.
The Argument from Conceivability
1. We can conceive of a mind without conceiving
of an associated brain. (Premise)
Therefore,
2. It is logically possible for a mind to exist without
an associated brain. (From 1)
3. If it is logically possible for x to exist without y,
then x and y are distinct. (Premise)
Therefore,
4. Minds and brains are distinct substances. (From
2,3)
Conceivability and Possibility
•
Inference from 1 to 2 in the Argument from Conceivability presupposes that if a proposition is
conceivably true, then it is logically possibly true.
•
It is conceivable that F exist without G = One can fully understand the concept of F without
understanding the concept of G, or vice versa.
–
Example: It is conceivable that Obama not be the 44th president of the USA.
•
A proposition p is logically possible = p is not self-contradictory.
•
A proposition is physically possible = it is consistent with the laws of physics.
•
Many propositions that are logically possibly true are in fact false.
–
•
Example: It is possible that Obama not be the 44th president of the USA.
Some propositions that are possibly true are even physically impossible.
–
Example: It is logically possible but physically impossible that E=mc3.
An argument for Premise 3
3. If it is logically possible for x to exist without y, then x and
y are distinct. (Premise)
Why think logical possibility is a good guide to sameness and
distinctness of substances?
1. If x = y, then whatever is true of x is also true of y.
2. It is logically impossible for y to exist without y.
3. If it is logically possible for x to exist without y, then there
is something true of x that is not true of y.
4. If it is logically possible for x to exist without y, then x and
y are distinct (x ≠ y).
Objection to the Argument from
Conceivability
1. We can conceive of a mind without conceiving of an
associated brain. (Premise)
Therefore,
2. It is logically possible for a mind to exist without an
associated brain. (From 1)
• Objection:
– The inference from 1 to 2 is invalid.
– Reason: Historically, our folk conceptions of things have been
poor guides to how the things really are. The concept of water
was once distinct from the concept of H2O. However, it is not
logically possible for water to exist without H2O. Therefore,
conceivability does not entail possibility.
The Problem of Mental Causation
• Two difficulties for dualist accounts of mental causation:
– Specification of a mechanism, i.e., a “series of intermediate steps or stages
that transform one state [e.g., desiring x and believing that φing will bring
about x] into another [e.g., φing]”;
– The Argument from Causal closure:
1. Every physical event is completely explained by physical causes. (Premise)
2. Human actions are physical events. (Premise)
Therefore,
3. Human actions are completely explained by physical causes. (From 1,2)
Therefore,
4. There is no room for non-physical causes in explanations of action. (From 3)
Therefore,
5. If dualism is true, then there is no mental causation. (From 4)