Substance Dualism - PowerPoint Presentation

Slide1

Substance DualismSlide2

Reading

Read Chapter 2 of Kim (Can skip or skim over 35-46)

Read Descartes Selections (

pgs

1-15) in the reader.

Focus

especially on pages 1-3, 5-7 and 12

-14.Slide3

The mind body problem

The mystery is how minds could possibly arise out of seemingly mindless matter.

Atoms, molecules, photons, etc. do not have minds.

Humans do.

But a human being is just a particular kind of animal.

Animals are physical things: they are entirely composed of molecules, atoms, etc.

If you bunch up a bunch of mindless particles in some super special way you get something that things, feels, believes, and fears.

How can this be?Slide4

The mind body problem

These issues are the focus of this course.

The Mind Body Problem

What is the relationship between

minds

and

physical things

?

Are minds physical things?

If not, how are they related to physical things?

If so, how are they differentiated from other physical things? What makes them so special?

How do you get minds from mindless matter?Slide5

The three ways it could be

Monism

Physicalism

:

All that exists are physical things. At bottom there is nothing but the sorts of things that figure in the language of physics. So minds are just some sort of complex physical thing.

Idealism:

All that exists are

minds

and

mental states

. There is no such thing as physical objects. Tables, chairs, and so on are just

ideas

of one kind or another. (Berkeley)

OR

Dualism:

Both minds and physical things exist and they are fundamentally different kinds of things. That is minds could exist independently of physical things and vice versa.Slide6

Mind as Soul

Substance dualism is the theory of mind that has (by far) the most adherents.

This is true both from a historical perspective, and as a report of people’s current beliefs.Slide7

Mind as Soul

On this view, the mind is something

fundamentally different

from the body.

It is not identical to the body

It can survive the death of the body

It could even inhabit a

different

body.

It could exist even if the physical world were entirely destroyed.Slide8

Mind as Soul

When people imagine their

soul

persisting after their deaths, it is typically the

mental characteristics

that they think are important.

Memories

Desires

IntentionsSlide9

Mind as Soul

The idea of our minds or souls being separable from our body is deeply ingrained.

Possibility of existence after the death of the body

Freaky Friday style body-swap cases

Ghosts/spirits

Astral projection

Reincarnation

Post Armageddon existenceSlide10

Substance Dualism

These things only seem possible if minds can exist entirely independently of physical bodies.

Substance Dualism

:

There are two fundamentally different substances in the world: minds and bodies.Slide11

Substance Dualism

Substance:

Is the stuff that has or instantiates properties

Has the capacity for independent existenceSlide12

Substance Dualism

According to the dualist:

Physical

things

have physical properties like mass, momentum, spatial location and so on.

Minds

have mental properties like believing, desiring, having a sensation, and so on.

A human being has both a mind and a physical body.Slide13

Reasons to Be a Dualist

By far the most common reason for someone to be a dualist is

their religion

.

As philosophers we must evaluate the arguments for and against the position.Slide14

Descartes’ Arguments

Descartes gives several arguments for substance dualism and others have been inspired by his writings.

We will look at three:

The Argument from Doubt

The Divisibility Argument

The Conceivability ArgumentSlide15

Cartesian Preliminaries

Descartes begins his

Meditations on First Philosophy

by attempting to call into question

all

his beliefs.

He is seeking a firm foundation on which to build the rest of his knowledge, so he will be

certain

of what he knows and what he doesn’t.

If

he can

possibly be deceived

about something, he resolves to withhold judgment on the matter.Slide16
Slide17

Cartesian Preliminaries

Evil Demon

Suppose that you have no body at all, and there is nothing in the universe but

you

and an all-powerful evil demon. The demon deceives you by giving you a series of experiences as of a physical world in which you have a body, interact with other people and so on. But

none of this is happening

. Really, you are just a disembodied soul floating in the void being massively deceived.

Can you rule out this possibility with absolute certainty?Slide18

Cartesian Preliminaries

Descartes concludes that it is

possible

that you are deceived about the existence of every physical thing, including your own body.

Does this mean you could be deceived about

everything

?Slide19

The Cogito

“No: if I convinced myself of something then I certainly existed. But there is a deceiver of supreme power and cunning who is deliberately and constantly deceiving me. In that case too, I undoubtedly exist, if he is deceiving me; and let him deceive me as much as he can, he will never bring it about that I am nothing so long as I think I am something. So, after considering everything very thoroughly, I must finally conclude that this proposition

I am, I exist

, is necessarily true whenever it is put forward by me or conceived in my mind.” (Reader 1) Slide20

The Cogito

As he puts it elsewhere:

Cogito ergo sum.

I think therefore I am.Slide21

Cartesian Preliminaries

But what kind of thing is he? Easy!

“A thing that thinks…A thing that doubts, understands, affirms, denies, is wiling, is unwilling, and also imagines and has sensory perceptions.”Slide22

Argument from Doubt

The Argument from Doubt

I cannot doubt that I exist. (Cogito)

I can doubt the existence of any physical thing. (Evil Demon)

Therefore, I am not identical to any physical thing.

Therefore, I am a thinking thing that is not identical to any physical thing.

If the argument is sound, it shows that there is at least one non-physical thing, and dualism is established.Slide23

Argument from Doubt

The Argument from Doubt

I cannot doubt that I exist. (Cogito)

I can doubt the existence of any physical thing. (Evil Demon)

Therefore, I am not identical to any physical thing.

Therefore, I am a thinking thing that is not identical to any physical thing.

If the argument is sound, it shows that there is at least one non-physical thing, and dualism is established.Slide24

Argument from Doubt

What justifies the inference from (1) and (2) to (3)?

Leibniz’s Law:

For all x and y, if x is the very same thing as y, then x and y have all the same properties.Slide25

Argument from Doubt

Any physical thing has the property of

possibly being doubted by Descartes.

Descartes’ mind does not have this property.

Therefore, by Leibniz’s law, they are not identical.Slide26
Slide27

Lennay

Kekua

(Artist’s Approximation)Slide28

Ronaiah

Tuiasosopo

Slide29

A Fallacious Inference

Manti

Te’o

reasons as follows:

I believe that

Lennay

Kekua

is dead.

I don’t believe that

Ronaiah

Tuiasosopo

is dead.

Therefore,

Lennay

Kekua

is not identical to

Ronaiah

Tuiasosopo

. Slide30

Argument from Doubt

The problem is that what a person

believes

,

doesn’t believe

, or

doubts

doesn’t tell us very much about

how things are.

For this reason you can’t apply Leibniz’s Law to

intentional properties:

Properties that essentially involve intentional states of some subject (e.g. being believed, doubted, desired, etc.)Slide31

The Argument from Doubt

Therefore, the Argument from Doubt relies on a

fallacious inference

and should be rejected.Slide32

The Divisibility Argument

The Divisibility Argument (Version #1)

My body is divisible.

My mind is not divisible.

Therefore, my mind is not identical to my body.Slide33

The Divisibility Argument

In at least one sense, it seems the mind

is

divisible.

I have individual beliefs, memories, desires, and so on.

Some of these could be removed and replaced with others

I also have different

cognitive faculties

: reasoning, perception, sensation, memory, language comprehension, etc.

If I receive a brain injury I could lose some of these things in the same way I could lose an arm or a leg.

Descartes’ seems to deny that the mind can be fragmented in this way, though it isn’t clear

why.Slide34

The Divisibility Argument

The Divisibility Argument (Version #2)

If you cut off my leg something has been taken from my body.

Nothing has been taken from my mind.

Therefore, my mind and body are distinct.Slide35

The Divisibility Argument

Two responses:

My mind

does

lose something, namely the capacity to feel my leg.

A

physicalist

need not say that the mind is identical to

the entire body

.

If the mind is the brain, say, then this is consistent with Descartes observations here.

But if you remove part of the brain this

does

(typically) have mental effects. Slide36

The Conceivability Argument

“First, I know that everything which I can clearly and distinctly understand is capable of being created by God so as to correspond exactly with my understanding of it. Hence, the fact that I can clearly and distinctly understand one thing apart from another is enough to make me certain that the two things are distinct, since they are capable of being separated, at least by God……On the one hand I have a clear and distinct idea of myself, in so far as I am simply a thinking, non-extended thing; and on the other hand I have a distinct idea of body, in so far as this is simply an extended, non-thinking thing. And accordingly, it is certain that I am really distinct from my body, and can exist without it.

” (Reader 7)Slide37

The Conceivability Argument

The Conceivability Argument

If I can conceive of some state of affairs without contradiction, then that state of affairs is possible

. (Premise)

I can conceive of myself as existing without my body.

(Evil Demon)

Therefore, it is possible for me to exist without my body.

It is not possible for my body to exist without my body existing

. (Logic)

Therefore, I am distinct from my body. (by LL)Slide38

The Conceivability Argument

The Conceivability Argument

If I can conceive of some state of affairs without contradiction, then that state of affairs is possible

. (Premise)

I can conceive of myself as existing without my body.

(Evil Demon)

Therefore, it is possible for me to exist without my body.

It is not possible for my body to exist without my body existing

. (Logic)

Therefore, I am distinct from my body. (by LL)Slide39

The Conceivability Argument

The entire force of the argument depends on premise 1: the claim that conceivability entails possibility.Slide40

Arnauld’s Triangle

Steve knows about right triangles, but does not know the Pythagorean theorem (a

2

+b

2

=c

2

)

Suppose we ask him if it is possible to build a room in the shape of a right triangle with the following dimensions: 4x7x10.

He may very well say yes!Slide41

Arnauld’s Triangle

Furthermore, he may try to imagine the room, plan where he would put furniture in it, etc.

But such a room is impossible!

Hence, the fact that Steve can

conceive

of such a room does not entail that the room is

possible

.Slide42

Amnesia Case

Suppose I have amnesia and don’t remember my name.

I hear about this terrible instructor: Tim Butzer.

I imagine a world in which Tim Butzer is dead and I am attending a party to celebrate his timely demise.Slide43

Amnesia Case

But since I

am

Tim Butzer, it is impossible for Tim Butzer to be dead, and for me to be attending a party!

Hence, conceivability does not entail possibility.Slide44

Hesperus and Phosphorus

Hesperus is the first visible star in the evening and Phosphorus is the last visible star in the morning.

Someone could imagine a case in which Hesperus is in the sky while Phosphorus is not.

Indeed they may think this happens every evening!Slide45

Hesperus and Phosphorus

But Hesperus and Phosphorous are actually both Venus!

So every time Hesperus is in the sky Phosphorous is too (they are the same thing).Slide46

Conceivability and Possibility

All three cases share a common feature: the subject in each is ignorant of some key facts about the case.Slide47

Conceivability and Possibility

But it seems as if Descartes (or we) could be in precisely the same situation with regards to the relationship between minds and bodies.Slide48

Conceivability and Possibility

Since conceivability does not entail possibility Descartes’ argument is not sound.

Therefore, we have no good argument for substance dualism.Slide49

Arguments Against Dualism

We have not seen any argument that establishes that dualism is true.

But this does not mean it is false. Slide50

Princess Elisabeth: Philosophical BadassSlide51

Elisabeth’s Objection

According to Descartes’ own physics physical things are causally affected by:

Momentum

Contact

Quality or shape of a surface

The these all require

extension

and/or

spatial location.

But the soul has none of these properties. So how does it cause the body to move?Slide52

Elisabeth’s Objection

This is a problem because Descartes accepts the following:

Interactionism:

Minds interact causally with physical things.

Minds can cause the body to move

Action on my body can cause mental states

And well he should!Slide53

Elisabeth’s Objection

“I confess it would be easier for me to concede matter and extension to the soul, than the capacity to move a body and to be moved, to an immaterial thing.” Slide54

Reading

Read:

Kim: 61-71

Ryle “Descartes’ Myth” (Reader 30-37)Slide55

Descartes’ Picture of Mind/Body CausationSlide56

Descartes’ Picture of Mind/Body Causation

The idea seems to be that since the gland is

so small

and

so central

in the brain, that any little movement could have big results.Slide57

Descartes’ Picture of Mind/Body Causation

But thinking in this way completely misses the point of Elizabeth’s objection:

It isn’t that it would be very hard for an immaterial thing to move a material thing

Her point is that it is impossible, even in principle, an immaterial thing to move a physical thing!Slide58

Descartes’ Responses

Here is a (somewhat unfair) summary of Descartes’ responses to Elizabeth:

Mind-body causation is like gravity (but gravity isn’t like that).

Mind-body union is a third substance (maybe?)

Mind-body interaction can’t be understood by philosophizing, so stop it.Slide59

Causal Overdetermination

According to every systematic theory of physics since Newton, every physical event in the universe

has a physical cause.

This is in tension with the dualist’s claims that

some

physical events have mental causes.Slide60

Causal Overdetermination

Say that I raise my hand.

According to our best physics, there is a physical cause sufficient to produce this action.

According to the dualist there is also a

mental cause

for this action.Slide61

Causal Overdetermination

What the dualist has to say to be consistent with our best science is that my raising of my arm was

causally

overdetermined

.Slide62

Causal Overdetermination

Causal

Overdetermination

:

An event A is causally

overdetermined

if it has multiple causes, each of which would have been sufficient on its own to cause A.Slide63

Causal Overdetermination

There are many events in the clip that would prevent O.J. from making the arrest:

Getting his leg caught in the door

Getting shot 15 times

Burning his hand

Being blinded by cake

Getting caught in a bear trap

Falling off the boatSlide64

Causal Overdetermination

So, O.J.’s failing to make the arrest was

causally

overdetermined

.

Causal

overdetermination

is clearly possible and sometimes happens.Slide65

Causal Overdetermination

However, as the clip

also

illustrates, such cases tend to be a matter of total coincidence.

As a result, though such cases are certainly possible, it seems that they are coincidental and rare.Slide66

Causal Overdetermination

The dualist must say that every time any person moves her arm, there is both a physical cause and a mental cause.

But this amounts to saying that there are

an enormous number

of mere coincidences happening all the time.Slide67

Causal Overdetermination

This massive coincidence calls out for some sort of explanation on the part of the dualist.

If mind’s and bodies interact, what explains the massive causal

overdetermination

that results?Slide68

The Moral

Elisabeth’s Objection and the problem of causal

overdetermination

seem to entail that

dualism

and

interactionism

are inconsistent.

But why can’t the dualist just deny interactionism?Slide69

Denying Interactionism

The problem for any view like this is to explain observed facts:

Every time I decide to raise my arm it goes up.

Every time someone punches me I feel pain.

Every time I want to move to the other side of the room, my body walks over there.

Etc.Slide70

Denying Interactionism

If my mind does not causally interact with my body, how are we to explain these very common observations?Slide71

Occasionalism

Malebranche suggested that every time you want to make your body move, God takes it as an occasion to intervene and cause your body to move in the way intended.

This doctrine is called

occasionalism

.Slide72

Occasionalism

According to

occasionalism

the laws of physics are violated every time I “move” my body.

Every time any person move’s their body is literally a miraculous event!Slide73

Pre-Established Harmony

Leibniz suggested that the apparent interaction was due to a

pre-established harmony:

God set up the universe with two distinct causal orders: the mental and the physical.

He set them up in such a way that though they never causally interact, they will always be in sync.

So when the mental event of my wanting to raise my arm happens, the pre-established harmony guarantees that my arm will go up.Slide74

Pre-Established Harmony

Think of two clocks set to the same time. They don’t causally interact, but they can be such that they always agree on the time.

Leibniz’ idea is that the relationship between the mental and physical is a lot like that.Slide75

Acts of Desperation

Both Malebranche’s view and Leibniz’ seem to be theoretic acts of desperation.Slide76

Acts of Desperation

Since dualism is inconsistent with this kind of interaction, it must be rejected.

Let’s adopt Elizabeth’s suggestion and consider the possibility that the mind is a material thing of some kind.