Theories of Mental Representation - PowerPoint Presentation

Slide1

Theories of Mental Representation

Part ISlide2

Vehicle vs. Content

Small [horse picture]

[Small horse] pictureSlide3

Vehicle vs. Content

Representational vehicles are the things that represent (we can just call them representations: words, maps, photos, beliefs.

The representational content of a representation is what it represents/ what it means.Slide4

Metasemantics

Since

most things

don’t have representational content

, and only a few things do,

it’s reasonable to ask: why do things like maps, sentences, and thoughts have content

and

rivers, lakes, and trees have no

content

? Slide5

Metasemantics

Why

is

a map of Hong Kong a map

of Hong Kong, rather than (say) a map of Kuala Lumpur?

Why

do

representational

things have the

content

s

they do rather than some other

content

?Slide6

Metasemantics

“Metasemantics” (metaphysical semantics, the metaphysics of meanings) is the part of philosophy of language that tries to answer the question:

“Why [in virtue of what] do

representations have

the content

s they do, rather than some other content, or no content

at all?”Slide7

The conformal theorySlide8

Aristotle

Aristotle (384-322 BCE) is in the running for “greatest Western philosopher” and he’s usually in everyone’s top 5 at least.

According

to Aristotle, substances are composed of matter + form. Slide9

Aristotle on Hylomorphism

Example

: a house is a substance. The matter of the house is the bricks, cement, plaster, wood, and so forth. But the house is not just the bricks and cement, etc. It is those bricks, cement, plaster, etc. arranged in a certain way: with a certain form. Slide10

The Conformal Theory of Representation

Aristotle held an obscure doctrine of the identity of the knower with the known.

When

I think of a house, for instance, my soul (i.e. my matter) takes on the form of a house. Thus, even though I (me, my soul, my matter) am distinct from a house (its matter), I represent the house because it and my soul have literally the same form (the form of a house). Slide11

Conformal Theory

RepresentsSlide12

Aquinas and the Conformal Theory

Aristotle’s

greatest medieval follower, St. Thomas

Aquinas (1225-1274 CE),

tried to deal with a problem in the conformal theory.Slide13

Problem for Conformal Theory

Represents???Slide14

Intentional Presence

The solution

Aquinas proposed was

that the house-form was not “really” present in me, it was only “spiritually” present. Spiritually present forms represent really present ones, but not vice versa.

(Incidentally, this is also the explanation for why even though I have the form of a house

,

I don’t look anything like a

house

.)Slide15

Conformal Theory

Represents

Real Form

Spiritual FormSlide16

The Idea Theory

The addition of “spiritual forms” to regular forms presaged what would become the dominant view of mental representations: the idea theory.Slide17

Idea theorySlide18

The Nature of Ideas

According

to Locke, ideas are “the pictures drawn in our minds” (Essay, II.x.5). Slide19

The Nature of Ideas

An idea of a horse, then, is very much like a picture, image, or painting of a horse.

Compare

Hume: “By ideas I mean the faint images of [perceptions] in thinking and reasoning” (Treatise, I.i.1).Slide20

Idea Theory

Mind

Idea of a Dagger

DaggerSlide21

Indirect Realism

The idea theory is a variety of “indirect

realism.” What you

directly

see are mental entities (for example, ideas). You only indirectly see the real things that the ideas represent.Slide22

Resemblance Theory

According

to the resemblance theory of representation, ideas represent things by resembling them– sort of like how painting works

.

The resemblance theory is thus a theory of what it is in virtue of which ideas have the contents they have: the ideas resemble the contents.Slide23

Idea Theory

Mind

Idea of a Dagger

Dagger

Resembles

SeesSlide24

Corpuscularianism

In the 17

th

Century,

corpuscularianim was the dominant scientific worldview. It held that all physical things are made of tiny little things called “corpuscles.”

The theory was very similar to Greek atomism, with the exception that atoms couldn’t be divided and corpuscles (in theory) could.Slide25

Corpuscularianism

Part of the theory held that corpuscles only had shape, size, solidity, and motion.

They did not have color, taste, texture, smell, or heat, though they could cause us to experience these things by exciting our sense organs.Slide26

Idea Theory

Mind

Idea of a Dog

Dog

Partly Resembles

SeesSlide27

Problems for the idea theorySlide28

4. Problems for the resemblance

theorySlide29

Problems for Resemblance Theory

Can’t distinguish concepts and propositions.

Resemblance is an equivalence relation, representation is not.

Resemblance is in some ways more and in some ways less determinate than representation.

Even photos and paintings don’t represent what they resemble.Slide30

Concepts

Concepts

are representations of things or qualities: so I can have a concept of Obama, or a concept of red, or a concept of a horse, or a concept of a concept.

Importantly, concepts are

not truth-evaluable

. My concept of red isn’t true, and it isn’t false either. It might be more or less accurate.Slide31

Propositions

We

can say that when I

think of

a thing, or think about a thing, then I am entertaining a concept.

However, when I think that

such-and-such, I am entertaining a proposition. Slide32

Propositions

For

example, I can think that Obama is the US president, or think that grass is red, or think that the concept of a horse is not a concept.

Propositions

are

truth-evaluable: when I think that grass is red, my thought is false. (Not so when I just think of red.)Slide33

The idea theory seems to have trouble distinguishing concepts and propositions.

According

to the idea theory, thought is having ideas, and ideas are like mental pictures. Are mental pictures truth-evaluable? If they are, then concepts aren’t ideas. If they aren’t,

then propositions aren’t ideas. Slide34

Equivalence RelationsSlide35

Resemblance as an Equivalence Relation

Resemblance, like identity, is an equivalence relation, meaning it’s reflexive, symmetric, and transitive:

Reflexive

: for all X, X resembles X. (Everything resembles itself.)

Symmetric: for all X and Y, if X resembles Y, then Y resembles X.

Transitive: for all X, Y, and Z, if X resembles Y and Y resembles Z, then X resembles Z.Slide36

Problem for the idea theory: resemblance is an equivalence relation, but representation is not. Therefore representation ≠ resemblance.Slide37

1. Representation is Not Reflexive

You can

have a representation that represents itself (for example, a map of Hong Kong that includes the map’s location), but most representations don’t represent themselves.

You

can have a painting of a horse, that is not a painting of a painting of a horse (not a painting of itself).Slide38

2. Representation is Not Symmetric

Most of

what gets represented is not representational. My thoughts represent lakes and rivers and trees, but lakes and rivers and trees don’t represent my

thoughts.

And

even when I do represent representations (when I think about a painting, say), usually they don’t represent me or my thoughts.Slide39

3. Representation is not Transitive

The

directory at the museum might represent the location of a certain Picasso painting. That painting could represent a horse. But the directory doesn’t represent any horses, it only represents paintings.Slide40

Indeterminacy and Error

Another class of problems for resemblance theories of representation involve indeterminacy and error.Slide41

Wittgenstein’s Man on the Hill

“A picture which corresponds to a man walking up a hill forward corresponds equally, and in the same way, to a man sliding down the hill backward.”

-- Philosophical InvestigationsSlide42

Wittgenstein’s Man on the Hill

“

Perhaps a Martian would describe the picture

[as the man sliding down].

I do not need to explain why we do not describe it so.”Representation can be

more determinate than resemblance.Slide43

Twins

Suppose

you met a woman last night and I met her twin. You and I both have memories (mental representations) of the women we met, and let’s suppose those mental images are identical in every

respect.Slide44

Twins

Here, even though the representational vehicles are the same, and thus resemble the exact same things, the representational contents are different.Slide45

Error

Consider

a revised version of the twins case: you and I separately meet each of two twins. They are exactly alike except that the twin you meet has a scar on her left cheek and mine has no scar. Slide46

Error

However

, the next day I falsely remember my twin as having a scar on her left cheek. Then the resemblance theory says

my memory is about the twin you

met.

Someone I’ve never met in my entire life!Slide47

Massive Error

Imagine that I have a pen pal whom I’ve never met, or seen a picture of. Over the course of our correspondence, I develop an elaborate mental image of her: what color her hair is, how big her nose is, etc. Suppose that my mental image is completely wrong and doesn’t resemble my pen pal at all. Slide48

Massive Error

On

the resemblance view, it would seem that I was incapable of thinking about her, for example, I couldn’t think: “Oh, here’s another letter from my pen pal!”Slide49

Conceptual Competence

One

direction for a solution to the problem of error is to say that my idea of my twin or my pen pal is only a “partial” idea or is an “incompletely grasped” idea or something like that. Slide50

Conceptual Competence

That

may be true, but this doesn’t really resolve the problem. Why is the idea– partial or incomplete as it is– an idea

of

my pen pal, rather than of someone else whom it more closely resembles, or of a mere fiction?Slide51
Slide52

Fodor vs. the Image Theory

Fodor holds that thought happens in a language (“the language of thought”) rather than in images– the ideas of the idea theorist. One argument goes like this: you can see a Necker cube in two different ways. There’s one picture that corresponds to two ideas. But if ideas are just mental pictures, what two

different

mental pictures correspond to the two different ways you can see the one physical picture?Slide53
Slide54

Seeing vs. Seeing-as

What the Necker cube example suggests is a more general problem. You can look at the Fischer cow and not see that it is a cow. When you see the picture

as

a cow, your perception changes. But if your idea of the picture is just a copy of that picture in your head, what about it changes such that once it was just squiggles and then it’s a cow?Slide55

Fodor vs. the Image Theory

Another argument is that the idea theorist doesn’t have a good story about my thought that I am NOT wearing a red shirt. Is it a picture of me wearing a blue shirt? Or a green one? What if I’m just thinking that I’m NOT wearing a red one, but not thinking of what color shirt I am wearing? Notice how “No smoking” signs have to resort to non-pictorial symbols. You can’t just have a sign where someone isn’t smoking.Slide56

Perhaps the biggest problem for the idea theory is that in most cases where x resembles y, x does not represent y.

Two cows for instance might resemble each other much more than our ideas, paintings, or photographs resemble them. Yet we have no inclination to say that the cows represent each other.Slide57

Hilary Putnam points out an interesting case. Imagine two lines in the sand. One has been drawn by a human with the intention of tracing the figure of Winston Churchill, and it resembles him (or his figure) a lot. The other has been traced by an ant just wandering aimlessly in the sand. But imagine that the ant’s line is identical to the human’s. We think the human-drawing represents Churchill, but the ant-line doesn’t.Slide58

This suggests that

drawings, paintings, and so forth don’t represent things by resembling them

. They represent things on the basis of our intentions.

But the entire motivation of the idea theory was to model ideas on drawings and paintings.

Those things represent by resembling, and that’s how ideas were supposed to work as well.