Transcript Lecture Note Pages for 2.3.

Section 2.3
I, Robot
Mind as Software
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Functionalism
• Mental states are functional states.
• To perform a function is to take a certain input and
produce a certain output.
• When two things perform the same function, they are
said to have the same “causal role.”
• The problem with this description is that it makes
functionalism easy to confuse with both logical
behaviorism and identity theory.
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A functional description of a heating system
http://www.mind.ilstu.edu/curriculum/functionalism_intro/res_functionalism_intro_overhead.php?modGUI=44&compGUI=1183&itemGUI=2056
Give heat as output only if the temperature is less than 68 degrees.
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A functional description of a heating system (at a more
concrete level)
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A functional description of a heating system (at an even
more concrete level)
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Now, consider just the first component of the function
system
• Now, suppose we just consider the the thermometer.
• We might have an interest in the physical properties of
the thermoeter, but we might not. We might instead be
interested solely in the thermoeter functional properties.
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Functionalism
A thermometer is functionally defined as a device which
measures temperature. Some physical change occurs in the
thermometer and this physical change is converted into a
readable value.
We can imagine a black box which encloses the thermostat,
hiding it from view. We can then do for the thermostat, what we
had initially done for the entire heating system -- we can give a
functional description of the thermostat.
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Functionalism
A functional description is concerned only with what it
takes as input and what it gives as output, ignoring
completely how it succeeds in performing that
function. The function of a thing is often called its
causal role.
Given that there are many ways to build a thermostat
that performs the "temperature detecting" function,
we say that a thermostat can be realized in many
different ways.
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Functionalism
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Artificial Intelligence
• The goal of artificial intelligence research is to create a
machine that can think for itself; that has a mind of its own.
• According to “strong AI,” there’s nothing more to having a
mind than running the right kind of program.
• Strong AI claims that the mind is to the brain as the software
of a computer is to its hardware.
• Mental States are functional states
• To have a mind is to have the right kind of program being run
on sufficiently rich and stable hardware.
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Functionalism
How is functionalism different from identity
theory. Multiple Realizability Problem.
How is functionalism different from logical
behaviorism?
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Frank Tipler
• Why would this view be important if it were
true?
• Would would hinge on it?
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Thought Experiment: Lewis’s
Pained Madman
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Functionalism and Feeling
1.
2.
3.
If functionalism were true, it would be impossible
for someone to be in pain and function differently
than we do when we are in pain.
But, as Lewis’s pained madman shows, it’s not
impossible for someone to be in pain and function
differently than we do.
So, functionalism is false; being in a certain
functional state is not a necessary condition for
being in a mental state.
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Thought Experiment: Block’s Chinese
Nation
• “Suppose we convert the government of China to
functionalism, and we convince its officials that it
would enormously enhance their international
prestige to realize a human mind for an hour.”
• Suppose the people of China run a mind program.
Would there now be another mind on Earth?
• This is known as the “absent qualia objection” to
functionalism.
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Block’s Argument
1. If functionalism were true, then anything that
had the right sort of functional organization
would have a mind.
2. But as Block’s Chinese nation shows, it is not the
case that anything that had the right sort of
functional organization would have a mind.
3. So functionalism is false; having the right sort of
functional organization is not a sufficient
condition for having a mind.
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Thought Experiment: Putnam’s Inverted
Spectrum
• “Imagine your spectrum becomes inverted
at a particular time in your life and you
remember what it was like before that.”
• Imagine further that you learn to function
as before.
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Putnam’s Argument
1.
If functionalism were true, it would be impossible for
people with the same functional organization to have
different mental states.
2.
But, as Putnam’s inverted spectrum shows, it’s not
impossible for people with the same functional
organization to have different mental states.
3.
So functionalism is false; having a certain functional
organization is not a sufficient condition for being in a
certain mental state.
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Thought Experiment: The Turing
Test
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Thought Experiment: Searle’s
Chinese Room
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Searle’s Argument
1.
2.
3.
If a computer could understand a language solely
in virtue of running a program, then the man in
the room would understand Chinese (because
he’s doing the same thing that a computer does,
namely, manipulating symbols in accordance
with a set of rules.)
But the man in the room doesn’t understand
Chinese.
So computers can’t understand a language solely
in virtue of running a program.
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Syntax and Semantics
• How a symbol can be combined with
other symbols to form a sentence is
determined by its syntax.
• What a symbol means is determined by
its semantics.
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Replies to the Chinese Room:
• Systems reply: the man in the room doesn’t understand
Chinese, but the whole system does.
• Robot reply: the man in the room doesn’t understand
Chinese, but if the room were put in a robot, the robot
would.
• Brain simulator reply: the man in the room doesn’t
understand Chinese, but if the program simulated nerve
firings, the system would.
• Combination reply: even if each of the above replies is
inadequate, taken together they would create a system
that understands Chinese.
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Intentionality
• Intentionality is the property of being
of or about something.
• Mental states have intentionality
because they can be of or about
something. The belief that the Yankees
will win the pennant, for example, is
about the Yankees, the pennant, and
the proposition that the Yankees will
win the pennant.
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