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Chapter 13
Artificial Intelligence
Artificial Intelligence
Artificial:
humanly contrived often on a natural model
Intelligence:
the ability to apply knowledge to manipulate one's
environment or to think abstractly as measured by
objective criteria
Clearly, intelligence is an internal characteristic.
How can it be identified?
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Thinking Machines
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A computer can do some things better --and
certainly faster--than a human can:
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Adding a thousand four-digit numbers
Counting the distribution of letters in a book
Searching a list of 1,000,000 numbers for
duplicates
Matching finger prints
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Thinking Machines
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Figure 13.1 A computer might have trouble
identifying the cat in this picture.
BUT a computer would
have difficulty pointing out
the cat in this picture, which
is easy for a human.
Artificial intelligence (AI)
The study of computer
systems that attempt to
model and apply the
intelligence of the human
mind.
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In the beginning…
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In 1950 Alan Turing wrote a paper titled
Computing Machinery And Intelligence, in
which he proposed to consider the question
“Can machines think?”
But the question is “loaded” so he proposed to
replace it with what has since become known
as the Turing Test.
“Can a machine play the Imitation Game?”
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The Imitation Game
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Skip detailed description
The Imitation Game
The 'imitation game' is played with three people,
a man (A), a woman (B), and an interrogator
(C) who may be of either sex.
The interrogator stays in a room apart from the
other two.
The object of the game for the interrogator is to
determine which of the other two is the man
and which is the woman.
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The Imitation Game
The interrogator is allowed to put questions to A
and B.
It is A's object in the game to try and cause C to
make the wrong identification.
The object of the game for the third player (B) is
to help the interrogator.
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The Imitation Game
We now ask the question, 'What will happen
when a machine takes the part of A in this
game?'
Will the interrogator decide wrongly as often
when the game is played like this as he does
when the game is played between a man and a
woman?
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The Imitation Game
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The Turing Test (objections)
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There are authors who question the validity of
the Turing test.
The objections tend to be of 2 types.
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The first is an attempt to distinguish degrees, or
types of equivalence…
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The Turing Test (objections)
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Weak equivalence: Two systems (human and
computer) are equivalent in results (output),
but they do not arrive at those results in the
same way.
Strong equivalence: Two systems (human
and computer) use the same internal processes
to produce results.
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The Turing Test (objections)
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The Turing Test, they argue, can demonstrate weak
equivalence, but not strong. So even if a computer
passes the test we won’t be able to say that it thinks
like a human.
Of course, neither they, nor anyone else, can explain
how humans think!
So strong equivalence is a nice theoretical
construction, but since it’s impossible to demonstrate
it between humans, it would be an unfair
requirement of the Turing Test.
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The Turing Test (objections)
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The other objection is that a computer might seem to be
behaving in an intelligent manner, while it’s really just
imitating behaviour.
This might be true, but notice that when a parrot talks, or a
horse counts, or a pet obeys our instructions, or a child
imitates its parents we take all of these things to be signs of
intelligence.
If a parrot mimicking human sounds can be considered
intelligent (at least to some small degree) then why wouldn’t
a computer be considered intelligent (at least to some small
degree) for imitating other human behaviour?
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Turing’s View
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“I believe that in about fifty years time it will
be possible to programme computers with a
storage capacity of about 109 to make them
play the imitation game so well that an
average interrogator will not have more than
70 per cent chance of making the right
identification after five minutes of
questioning.”
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Context
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In 1950, computers were very primitive.
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UNIVAC I was the first commercial computer
made in the United States. It was delivered to the
United States Census Bureau on March 31, 1951!
At a time when the first computers were just
being built, to suggest that they might soon be
able to think was quite radical.
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Objections Turing Foresaw
1.
2.
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6.
7.
8.
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The Theological Objection
The 'Heads in the Sand' Objection
The Mathematical Objection
The Argument from Consciousness
Arguments from Various Disabilities
Lady Lovelace's Objection
Argument from Continuity in the Nervous System
The Argument from Informality of Behaviour
The Argument from Extra-Sensory Perception
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Can Machines Think?
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No machine has yet passed the Turing Test.
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Loebner Prize established in 1990
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$100,000 and a gold medal will be awarded to the
first computer whose responses are
indistinguishable from a human's
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Aspects of AI
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Knowledge Representation
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Semantic Networks
Search Trees
Expert Systems
Neural Networks
Natural Language Processing
Robotics
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