Physicalism - PowerPoint Presentation

Slide1

PhysicalismSlide2

From last time: Abductive argument for materialismSlide3

The Abductive Argument

Here’s an argument against Berkeley:

“Look, the existence of a mind-independent reality is the

best explanation

for our experiences. If tables and chairs etc. were ‘just ideas’ that wouldn’t explain why everyone looking in the same place sees the same thing.”Slide4

Reply

: This requires that the physical objects cause our ideas. But no-one has

any clue

how physical-to-mental causation is supposed to work. So this can’t be the

best

explanation.Slide5

Furthermore, according to

corpuscularianism

, our ideas are caused (mysteriously) by the shape size and motion of the corpuscles acting on our sensory organs. But:

(a) Shape, size, and motion

are

ideas

(b) Ideas are passive: they cannot cause a

change in other ideas

.__________________

(c) Therefore, shape, size, and motion can’t cause a change in our ideas.Slide6

Outstanding Issues

OK, but how can Berkeley explain:

The fact that our experiences are regular and lawful.

The fact that our experiences are inter-subjectively verified.

The fact that there’s a difference between hallucination, imagination, and sensing.

The fact that tables and chairs exist even when no one is perceiving them.Slide7

Berkeley’s MetaphysicsSlide8

RegularitySlide9

Inter-SubjectivitySlide10

HallucinationSlide11

PersistenceSlide12

Why Believe It?

(a) Ideas can’t cause ideas; they are passive

(b) Physical substances can’t either; they don’t

exist_________________________________

(c) Presumably, then, a mental substance must be the cause.Slide13

The Mind is Not Me

It

is clear that I produce some of my ideas, as in imagination.

But most of my ideas are not produced by my own will; so they must be produced by the will of another.Slide14

The Mind is Wise and Benevolent

Sense ideas (a) are more strong, lively, and distinct than the ideas of imagination and (b) have a steadiness, order, and coherence lacking in the

latter.

Berkeley says these facts testify to the “wisdom and benevolence of [their] author”Slide15

receptionSlide16

Samuel Johnson (1709-1784)

Samuel Johnson was a poet and essayist in Britain, one of the most important British literary figures, and a contemporary of Berkeley.

James Boswell, his biographer, conveys the following story in

Life of Samuel Johnson

.Slide17

Samuel Johnson vs. Berkeley

“After

we came out of the church, we stood talking for some time together of Bishop Berkeley's ingenious sophistry to prove the nonexistence of matter, and that every thing in the universe is merely ideal. I observed, that though we are satisfied his doctrine is not true, it is impossible to refute it. I never shall forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it

– “I

refute it

thus

.””Slide18

reductionismSlide19

Life Force

Most cultures throughout history have believed in some sort of “life force.”

Qi in China,

prana

in India, or élan vital in the West.Slide20

Vitalism

“

Vitalists

hold that living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things

.”

--“

Vitalism

,”

Routeledge

Encylopedia

of PhilosophySlide21

Vitalism

After the advent of chemistry in the West, “

vitalism

” was associated with testable scientific claims. For example:

No organic material can be made from only inorganic components.

Certain processes (e.g. respiration, fermentation) require living organisms to take place.Slide22

Molière’s The Imaginary Invalid

1

st

DOCTOR:

Most

learned bachelor

Whom I esteem and honor,

I would like to ask you the cause and reason why

Opium makes one sleep

.

ARGAN:

...The reason is that in opium resides

A

dormitive

virtue

,

Of which it is the nature

To stupefy the senses.Slide23

The Wöhler

Synthesis

In 1828, German

chemist Friedrich

Wöhler

synthesized the organic chemical urea from inorganic materials.

(Now we know how to synthesize them all.)Slide24

The Periodic Table

41 years later, Dmitri Mendeleev published a periodic table of the elements. It wasn’t the first such table, but it was the first to rearrange elements out of strict atomic-weight order and to leave gaps where the known elements didn’t fit.Slide25

Quantum Mechanics

Subsequently, the development of quantum mechanics in physics allowed us to explain the periodic chemical features that appear in the table in terms of the physical properties of each element.Slide26

Reductions

Biological

↓

Chemical

↓

PhysicalSlide27

Reductions

Mental? Moral? Modal?

↓?

Biological

↓

Chemical

↓

PhysicalSlide28

Dependence Slide29

Physicalism

Physicalism

says that only physical objects and only physical properties exist.

Does that mean that the three spooky M’s don’t exist? What is it for

everything

to be physical?Slide30

Modality

There are ways that the world

is

. For example, donkeys are not, in fact, capable of speech.

But there are also ways that the world

could have been

. Donkeys could have been able to talk, even though in fact they can’t.Slide31

Could Have ExistedSlide32

Possible Worlds

Philosophers like to talk about “possible worlds.”

In this way of talking, every way that our world could have been is a way that some world is.

So, for example, there’s a possible world where donkeys talkSlide33

It could have been true that P

=

In some world it is true that PSlide34

Seurat, La Seine á L

a Grande-

JatteSlide35

Seurat, La Seine á L

a Grande-

JatteSlide36

Supervenience

The A-properties supervene on the B-properties =

def

any two possible worlds with the same B-properties have the same A-properties.Slide37

Problem

Ectoplasmic

gooSlide38

Physicalism

So we might say that

physicalism

is the following claim:

All properties supervene on physical properties. Any two worlds with all the same physical properties have all the same properties.Slide39

What is “physical”?Slide40

Physicalism

says that only physical objects and only physical properties exist.

But what does it mean for something to be

physical

?Slide41

First Pass

A property or object is physical =

def

that property or object appears in the laws of physics (as they now stand).Slide42

The Standard ModelSlide43

Things That Might Be Missing

A theory of gravity. Some physicists believe there are particles called gravitons.

A theory of dark matter. Our best guess is that this will involve WIMPs: weakly interacting massive particles.

Supersymmetry

: although there’s no evidence, a lot of our physical theory would be simplified if some of the standard particles had “

superpartners

.”Slide44

Main Issue

Main issue: standard physics is either wrong or only partly right. There are things (though we don’t know what) that it does not talk about.

If the physical things are the things physics talks about, then

physicalism

is false: not everything is a thing physics talks about.Slide45

Second Pass

Suppose that we have an extremely long time to investigate the universe, and that we’re all really committed (and good) scientists, and that we have unlimited funding and manpower for our investigations. Eventually we come to a satisfying physical theory that every one of us agrees to. Call this the Ideal Final Theory.Slide46

Second Pass

A property or object is physical =

def

that property or object appears in the Ideal Final Theory.Slide47

Main Issue

Isn’t it possible that the Ideal Final Theory = Subjective Idealism? If Subjective Idealism counts as

physicalism

, then everything counts as

physicalism

.Slide48

Hempel’s Dilemma

Either (a) we define

physicalism

as the thesis that everything is something that current physics talks about OR (b) we define it as the thesis that everything is something that physics should or would (in an ideal situation) talk about.Slide49

Hempel’s Dilemma

If (a), then

physicalism

is probably false.

If (b), then

physicalism

is true, but trivially so: it’s true no matter what the facts are.Slide50

False Dilemma

But it’s not true that those are the only ways to define

physicalism

. In fact, those are bad definitions.

Surely there are possible worlds that have nothing but physical things in them, but don’t have any of the things our world has in it.Slide51

Or Are There?

Or maybe there’s no sense to be made of a physical/ non-physical distinction.