Mental Causation
Supervenience
We say that the A-properties supervene on the
B-properties when:
There cannot be a difference in the A-properties
unless there is a difference in the B-properties.
Example
Economic properties supervene on physical
properties:
It’s impossible for you to have more money than
you now have, and yet for the world to be
exactly the same physically.
Supervenience vs. Identity
Supervenient properties need not be identical to
their supervenience bases.
Many philosophers think that moral properties
(right and wrong) are not physical properties.
But many still believe that you can’t have two
actions that are exactly alike physically, where
one is right and the other is wrong.
Mental States
A common claim of both epiphenomenalists and
physicalists is that mental states supervene on
physical states.
You can’t have a difference in mental states
without there being a difference in physical
states (e.g. brain states or behavioral states).
Physicalism
For both the Identity Theory and (Physicalist)
Functionalism, the supervenience of the mental
on the physical is obvious.
If mental states are the same as brain states,
then of course there’s no difference in the
mental states unless there is a difference in the
brain states: they’re the same thing!
Epiphenomenalism
For the epiphenomenalist, supervenience is
(usually) true, even though mental states and
brain states are different things.
Compare Chalmers’ Principle of Organizational
Invariance: “any two systems with the same
fine-grained functional organization will have
qualitatively identical experiences.”
THE PROBLEM OF CAUSAL
EXCLUSION
Economic Properties
Economic properties (having $5) supervene on
and are multiply realized by physical properties.
Having $5
Causal Exclusion
What causes the vending machine to give me a
beverage: the fact that the thing I put in it is
worth $5 (economic property) or the fact that
the thing I put in it has certain physical features
(physical properties)?
Physical Features
We’re tempted to say “physical features.” This is
because:
• Physically similar pieces of metal will also get
me a beverage, even if they are not worth $5.
• Many things that are worth $5 will not get me
a beverage, even if I fit them through the
payment slots (like checks for $5 or RMB
worth $5HKD).
Functionalism
Functionalism says that mental states supervene
on and are multiply realized by physical states
(like brain states in humans or silicon chips in a
robot).
Mental States Cause Behavior
Intuitively, the desire to
raise my hand is the cause
of my hand-raising
behavior.
But we can ask the
functionalist: is it the
mental state (desire) or its
realizer (neurons) that
causes the behavior?
A Neurological Story
One reason to think it’s
the physical properties is
that we can tell a
complete physical story
about propagating nerve
impulses that shows how
the physical condition of
our nervous system brings
about our behavior.
The second reason is that we could have
something with the same physical properties as
the realizer of the mental property (desire to
raise my hand), and it would also cause me to
raise my hand, even if it didn’t realize the
mental property.
Desire/ Hand Raising
Stimulus
Response
Other Mental States
Not a Desire/ Hand Raising
Stimulus
Response
World Causes Mental States
We could make the same argument regarding
physical states causing mental states.
If a physical state of the world causes a belief X
realized by a brain state, is it because X is a
belief or because of X’s non-mental properties
(location, weight, electrical charge) that the
world causes X?
Mental or Physical Causation?
Light bounces off a dog
and causes me to believe
that there’s a dog.
Suppose X is the neural
state that realizes my
belief. Did the light
bouncing off the dog
cause X because X was a
belief that there’s a dog?
First Reason
The first reason to think it’s the physical
character of X that explains why it’s caused and
not the fact that it realizes a belief is that we can
tell a complete physical story about what
happens without mentioning that X is a belief.
The second reason, again, is that something
with the same physical properties that is NOT a
belief would still be caused by light bouncing off
the dog.
Belief/ Dog Bouncing
Stimulus
Response
Other Mental States
Not Belief/ Dog Bouncing
Stimulus
Exercise
Exercise: Figure out how the same argument
would work for mental-state to mental-state
causation.
Problem for Functionalism
1. Obviously, mental states cause actions,
because they’re the mental states they are.
2. Obviously, states of the world cause mental
states, because they’re the mental states
they are.
3. Obviously, mental states cause mental states,
because they’re the mental states they are.
4. But for Functionalism, all of these are false.
Epiphenomenalism
Does it help to be an epiphenomenalist?
No, because epiphenomenalists don’t think
mental states have causal powers. So they can’t
explain the obvious facts either.
Possible Solution #1
Possible solution #1: Be an identity theorist.
Problem: Multiple Realizability
Possible Solution #2
Possible solution #2: Causal overdetermination.
Problem: Unlikely
Sometimes behavioral effects are causally
overdetermined.
I might laugh both because Mr. X tripped and fell
and because Ms. Y told me a funny joke, all at
the same time.
But normally my laughing has only one cause.
Possible Solution #3: Everyone’s
Problem is No One’s Problem
Being a wing supervenes on and is multiply
realized by physical properties of things.
You can give exactly similar arguments that
show that wings don’t cause things to fly
because they’re wings. They just cause things to
fly because of their physical configuration.
Possible Solution #3: Everyone’s
Problem is No One’s Problem
So solution #3 says: it’s difficult to see how to
get out of this problem.
BUT obviously there’s a way out, because wings
cause things to fly.
THEREFORE, there’s obviously a way out of the
causal exclusion problem. We just haven’t found
it yet.
Problem
This isn’t really intellectually satisfying.
Furthermore, in certain cases, it’s not obvious
that the supervening property has any causal
relevance. Remember the vending machine!
Possible Solution #4: “Causal
Relevance”
Define causal relevance as follows: a multiply
realizable property P is causally relevant to X := P
can be realized by physical properties A, B, C,…
where A causes X, and B causes X, and C causes
X, and…
Good Looks
Good Looks
Good Looks
Problem
Causal relevance ≠ causation.
If we say that multiply realizable properties can
be causally relevant, but can’t themselves cause
anything, the result is pretty weird.
It’s plausible that only the most basic,
fundamental properties of physics are not
multiply realizable.
CAUSAL EFFICACY OF CONTENT
Breaking Glass
https://www.youtube.com/watch?v=IZD8ffPwX
Ro
Representational Properties
An opera singer can (theoretically) break a
crystal wine glass with her voice.
Suppose she’s singing about love. That doesn’t
matter. The physical properties of her voice AND
NOT what they mean are causally relevant/
causally efficacious.
Mental Representation
Later in class we’ll talk lots about mental
representation. The general idea is that beliefs
like the belief that there is a dog represent
things (like the fact that there is a dog).
Mental Representation
We’d like to think that the representational
properties of mental states are causally efficacious:
1. the belief that there is a dog and
2. the belief that all dogs are animals
causes
3. the belief that there is an animal
because what the first two represent entail what
the third belief represents.
The Opera Problem
But the case looks a lot like the opera singer. If
beliefs are realized by brain states, what a brain
state can do is determined by its physical
properties– not by what it represents!
The Transitivity of Causes
Causal Theories of Representation
Represents