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24.09 F11 24.09 Minds and Machines Fall 11 HASS-D CI from the identity theory to functionalism Image by MIT OpenCourseWare. 1
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from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

Mar 31, 2020

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Page 1: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

24.09 F11

24.09 Minds and Machines Fall 11 HASS-D CI

from the identity theory to functionalism

Image by MIT OpenCourseWare.

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Page 2: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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roadmap

argument D (D+)

behaviorism

the identity theory

ripke’s bjectionK

o

functionalism (a more general version of the computer model of the mind)

Image removed due to copyright restrictions.

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Block, ‘Functionalism’

Cartesian Dualism said the ultimate nature of the mental was to be found in a special mental substance. Behaviorism identified mental states with behavioral dispositions; physicalism in its most influential version identifies mental states with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to sensory inputs and behavioral outputs. Functionalism is one of the major theoretical developments of Twentieth Century analytic philosophy, and provides the conceptual underpinnings of much work in cognitive science.

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Page 4: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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Putnam on the identity theory

The [type-type] identity theorist] has to specify a physical-chemical state such that any organism (not just a mammal) is in pain if and only if (a) it possesses a brain of a suitable physical-chemical structure; and (b) its brain is in that physical-chemical state…it must be a state of the brain of any extra-terrestrial life that may be found that will be capable of feeling pain…

Putnam, ‘The nature of mental states’

Image removed due to copyright restrictions.

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Page 5: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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‘replacement’ thought-experiments

a gradual replacement, one neuron at a time, with a chip that has the same input-output profile

is this any worse than a cochlear implant?

Image removed due to copyright restrictions.A RoboCop movie poster.

Image removed due to copyright restrictions.A Six Million Dollar Man poster.

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Page 6: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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an (apparent) lesson

minded creatures can in principle be made out of anything, provided certain structural constraints are met

you couldn’t make a mind out of Jello, but you could make one out of silicon chips

Image removed due to copyright restrictions. Bowls of Jell-O.

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Page 7: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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lessons from our discussion of behaviorism

mental states are the inner causes of behavior

the correspondence between mental states and behavior is many-many

(a) mental state M may produce different sorts of behavior, depending on the creature’s other mental states

(b) the same behavior may be produced by different mental states

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Page 8: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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example 1: the mousetrap

mousey inputdead/trappedmouse output

The mousetrap

Image by MIT OpenCourseWare.

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multiple realizability

Images removed due to copyright restrictions. Three different mouse traps.

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Page 10: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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the mousetrap is...

...the simplest sort of functional ions. kind

since no constraints are placed on its inner organization, it is also a behavioral kind

Image removed due to copyright restrictMickey Mouse.

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Page 11: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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example 2: the three-coke vending machine

M3 I0 M2 I0 M1 I0 M3 I1 M2 I1 M1 I1

“25¢” “25¢” “25¢”

shutM3 I1 M2 I1 M1 I1 M2 I0 M1 I0 down

initial states

output for

5¢ input

next states

2 Images by MIT OpenCourseWare.

Image by MIT OpenCourseWare.

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Page 12: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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the vending machine...

...can be multiply realized

it is a functional but not behavioral kind

what are the functional states M3, I2, etc?

the table tells the whole story

Image by MIT OpenCourseWare.

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functionalism

the view that mental states are functional states—states specified in terms of their causal relations to inputs, outputs, and other states

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Image by MIT OpenCourseWare.

Page 14: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

functionalism and the lessons

1. mental states can be multiply realized

2. input-output isn’t enough: it’s what’s in between that matters (recall the Aunt Bubbles machine)

3. mental states are the inner causes of behavior

4. the correspondence between mental states and behavior is many-many

functionalism accommodates all the above

Image removed due to copyright restrictions.

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Page 15: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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the three-coke vending machine again

the functionalist says that mental states can bespecified like Mi, Ij - in terms of their causal relations

to each other and to inputs and outputs

Image by MIT OpenCourseWare.

Image by MIT OpenCourseWare.

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Page 16: from the identity theory to functionalism · 2020-01-04 · with brain states. Functionalism says that mental states are constituted by their causal relations to one another and to

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the simple Turing machine table again

statescanned cell

S1 S2

1 R, S1 H

0 1, S2 H

similarly, the functionalist says that mental states can be specified like S1 and S2—in terms of their causal relations to each other and to inputs and outputs

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otherwise, proposition p is knowable (only) a posteriori

a posteriori and a posteriori and necessary: contingent:

water=H2O it’s cloudy

a priori and a priori and necessary: contingent:

2+3=5 ??

philosophical toolkit: a priori and a posteriori

(knowable) proposition p is knowable a priori iff p can be known independently of experience

Tool Kit

Image by MIT OpenCourseWare.

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Putnam

this paper is difficult and we won’t be discussing everything in it: just give it a skim on the first reading, concentrating on the ‘twin-earth’ example

Image by MIT OpenCourseWare.

reading for next session

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