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=IZD8ffPwXRo

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