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1 For next class… read to the end Chapter 1, section1.3
1
For next class… read to the
end Chapter 1, section1.3
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MIND
WHAT IS A MIND?
COULD WE MAKE A MACHINE THAT
THINKS?
WHAT IS THE RELATIONSHIP BETWEEN
MIND AND BODY?
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THE MENTALIST VS. THE BEHAVIORIST
• THE MENTALIST.
• STARTS WITH THE INTUITION THAT THERE IS A CLEAR DIFFERENCE
BETWEEN PEOPLE AND “SEEMINGLY INTELLIGENT” THINGS, SUCH
AS COMPUTERS OR ROBOTS.
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THE MENTALIST VS. THE BEHAVIORIST
• THE MENTALIST.• Starts with the intuition that there is a clear difference
between people and “seemingly intelligent” things, such ascomputers or robots—that only people can “mean what theysay”.
• No one thinks that a radio “means what it says”—that there is alittle person in the radio itself who is speaking to you. Rather, aradio merely transmits the sounds of the voices of other people.
• No one thinks a record or a CD or any other recording deviceis genuinely intelligent, that it “means why it says”: these aresimply a “read/write” device, that encodes sound signals andthen re-produces them.
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WHAT ABOUT COMPUTERS?
The ELIZA Program (Weizenbaum, 1966)
A program designed to mimic the conversation between a patient and a
therapist.
http://www-ai.ijs.si/eliza/eliza.html
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Does Eliza mean what “she” says?
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Does Eliza mean what “she” says?
No.
Eliza is simply giving the answers/asking the
questions which “she” has been programmed
to answer.
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This type of program—of which there are now
many and which became known as an Eliza
program—works in a very simple way:
• It is designed to work within a very restricted range of
situations — what therapists say to patients, what waiters
say to diners, what rental car employees say to
customers.
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This type of program—of which there are now
many and which became known as an Eliza
program—works in a very simple way:
• It is designed to work within a very restricted range of
situations — what therapists say to patients, what waiters
say to diners, what rental car employees say to
customers.
•The program is composed of simple text insertion rules,
rules based on the programmer’s understanding of the
nature of such conversations.
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Sample rules:
(X me Y) ---> (X you Y)
(I remember X) ---> (Why do you remember X just now?)
(My {family-member} is Y) ---> (Who else in your family is
Y?)
(X {family-member} Y) ---> (Tell me more about your
family)
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So….
Eliza doesn’t understand anything about
psychotherapy, the program simply uses rules,
based upon keywords that occur in therapeutic
situations, to construct replies.
There is no more understanding here than on a CD
or a record.
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Going back to
THE MENTALIST VS. THE BEHAVIORIST
• THE MENTALIST
• Starts with the intuition that there is a clear difference between people and
“seemingly intelligent” things, such as computers or robots.
• It does not matter how complicated a computer’s program, a computer does
not have a mind: it cannot mean what it says or intend to do what it does.
This is because it is NOT a conscious being, a thing must be conscious in
order to be capable of understanding and intending.
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THE BEHAVIORIST
Of course it is true that any computer that had an Eliza program
would not be an intelligent being: Eliza is an inflexible, simple
text replacement program confined to a single domain of
interest.
But if it were possible to create a program that responded in a
creative, flexible, and cogent way in conversation with a human
being, then we would have no reason to think that we hadn’t
created a mind.
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(PHILOSOPHICAL) BEHAVIORISM
To have a mind—to understand a sentence or to
intend to do some action—just IS to behave in the
appropriate ways (e.g. to say the sorts of things
people say when they understand a conversation.)
This is what is means to have a mind—to behave in
the correct sort of way.
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(PHILOSOPHICAL) BEHAVIORISM cont’d…..
Note that philosophical behaviorism is a bit trickier
than this statement makes it look.
The behaviorist is not talking about the actual
behavior of the computer or the person, but rather
about what the computer would do in a variety of
circumstances—about the person’s/machine’s
abilities to behave. (In behaviorist terms, these
abilities dispositions to behave.)
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(PHILOSOPHICAL) BEHAVIORISM cont’d…..
Note that philosophical behaviorism is a bit trickier
than this statement makes it look.
The behaviorist is not talking about the actual
behavior of the computer or the person, but rather
about what the computer would do in a variety of
circumstances.
For example, even if Eliza sounded convincing in one or
two “sessions” that would not be enough for the behaviorist
to decide whether Eliza understood the conversation, given
how easy it is to trip up Eliza.
Eliza would have to be capable of consistent appropriate
responses across a wealth of conversational
situations—just like people are.
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An example.
To be depressed simply means is to behave in a
certain depressed kind of way—to loose interest in
the things that normally interest and amuse you, to
withdraw from normal social interaction, to develop
abnormal sleeping and eating patterns, to say
things like “what is the use of anything?”, to stop
planning for or looking forward to future events, to
become upset or cry as a result of relatively minor
daily stresses, to react strongly negative facts about
the world (a news cast about famine, say).
HOWEVER, what is not required is that the person
feel depressed (although depressed people
normally do report this!).
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Both Mentalism and Behaviorism are
problematic
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A Problem with Mentalism.
1) Given that the only mind to which you have direct
access is your own, your belief that other people have
minds (e.g. your mother) must be based upon other
people’s behavior.
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A Problem with Mentalism.
1) Given that the only mind to which you have direct
access is your own, your belief that other people have
minds (e.g. your mother) must be based upon other
people’s behavior.
2) If you were to see an android, who behaved exactly like
your mother, you would have exactly the same
evidence that the android had a mind as you normally
have that your mother has a mind.
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A Problem with Mentalism.
1) Given that the only mind to which you have direct
access is your own, your belief that other people have
minds (e.g. your mother) must be based upon other
people’s behavior.
2) If you were to see an android, who behaved exactly like
your mother, you would have exactly the same
evidence that the android had a mind as you normally
have that your mother has a mind.
3) Given that you do believe your mother has a mind, you
should also believe that the android has a mind.
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To put this problem slightly differently…
If you have no reason to believe that the android has
a mind, then you have no reason to believe that your
mother has a mind.
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A Problem with Behaviorism
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A Problem with Behaviorism
From the inside, we know that we are conscious beings—we
consciously think, feel, and form desires.
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A Problem with Behaviorism
From the inside, we know that we are conscious beings—we
consciously think, feel, and form desires.
So although it might be possible to be depressed (for example)
and not feel “weepy” (or whatever)—to feel utterly numb,
absolutely nothing—surely having some conscious thoughts,
feelings, etc. is necessary for having a mind.
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A Problem with Behaviorism
From the inside, we know that we are conscious beings—we
consciously think, feel, and form desires.
So although it might be possible to be depressed (for example)
and not feel “weepy” (or whatever)—to feel utterly numb,
absolutely nothing—surely having some conscious thoughts,
feelings, etc. is necessary for having a mind.
It comes back to the intuition with which mentalism began: there
is difference between a person and a rock and a central
difference is that persons have conscious minds.
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Going back to the beginning, to our modern notion of mind…
Descartes’ Dualism
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Going back to the beginning, to our modern notion of mind…
Descartes’ Dualism
1. There are two distinct substances (types of “stuff” in the
world), Mind and Matter/Body.
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Going back to the beginning, to our modern notion of mind…
Descartes’ Dualism
1. There are two distinct substances (types of “stuff” in the
world), Mind and Matter/Body.
2. The essence of mind is thought (= any conscious state).
An Essence: That which makes something what it is, and
without which, it would not be what it is.
More formally.. An essence of something K = those
properties that are both necessary and sufficient for
something to be a K.
E.g. The essence of water is being composed of H2O.
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3. The essence of body/matter is extension—something that
occupies space.
4. No two substances can have the same essence.
5. You are essentially a mind, not a body. That is, you would
not be you without your mind (you = your mind), but you could
exist without your body (and hence possibly survive death).
Given (1) - (4) Descartes holds that:
Minds think whereas Matter does not.
Matter exists in space whereas Mind does not exist in space.
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Dualism gives rise to two immediate questions:
1. The Problem of Other Minds. How do we know
that anyone else has a mind, given that we have
access to only their behaviors?
“Absolute solitude is on this showing the ineluctable destiny of the
soul. Only our bodies can meet.” (Gilbert Ryle, The Concept of
Mind)
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2. The Mind-Body Problem. What is the relation between
the mind and the body?
“..the problem how a person’s mind and body influence each other is
notoriously charged with theoretical difficulties. What the mind wills, the legs,
arms and tongue execute; what affects the ear and the eye has something to do
with what the mind perceives. ….But the actual transactions between the
episodes of private history and those of the public history remain mysterious
since by definition they belong to neither series. They could not be reported
among the happenings described in a person’s autobiography of his inner life,
but nor could they be reported among those described by someone else’s
biography of that person’s overt career. They can be inspected neither by
introspection nor by laboratory experiment. They are theoretical shuttlecocks
which are forever bandied from the physiologist back to the psychologist and
from the psychologist back to the physiologist.” (p. 32-33. Ryle, The Concept
of Mind)
