PHILOSOPHY OF MIND
TURING, “MACHINE INTELLIGENCE”
STUDY GUIDE
PROFESSOR JULIE YOO
Name: ________________________________
Background: Part I - What Is a “Digital Computer”?
A computer is a device that performs computations. A computation DOES things to inputs
according to a set of instructions; the instructions specify certain information to be produced as
outputs on the basis of (other) information that is fed in also in the form of information. The
instructions specify an algorithm or what’s also called an effective procedure. An algorithm
satisfies two conditions:
1. Following a step requires no guesswork, imagination, or insight - no “intelligence.”
2. The number of steps is finite.
Shich instructions are an algorithm, which are not? Turing’s proposal: if you can transform the
instructions that can be executed by “the simplest possible device,” what people call a “Turing
Machine,” which is an abstract device that can do these things:
1. an endless tape that can be written on and erased
2. a head that can read, write on, and erase the tape
3. instructions that tell the head what to do
Background: Part I - Example of a Turing Machine Computation
We can see this with the example of adding “1” to a string of “1”s. (My instructions don’t
require the head to write over the symbol unless a revision is needed):
1. If the machine is in state A and the head reads a “0” then move one square to R and
stay in state A
2. If the machine is in state A and the head reads a “1”, then move one square to R and
move to state B
3. If the machine is in state B and the head reads a “1” then stay in state B and move one
square to R
4. If the machine is in state B and the head reads a “0” then erase it and write a “1,” go
into state A and stop.
The fact that these instructions unequivocally specify how to compute the function (x + 1) makes
for a systematic process. Notice that there is nothing essential about using the signs “0” and “1.”
They are symbols. They need not always represent numbers. They consist of two components:
syntax: physical features whose arrangement is assigned a meaning
semantics: meaning or representational content
This means that we can also “code” whatever we wish (binary code to represent numbers), and
this includes the instructions for TMs themselves (TM table). Thus a TM table can be coded and
then read by another TM* and so on, so that the TM* can do whatever the original TM could do
and more; the “super-TM” being what we call a universal TM. The beauty of the computer is
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that it can perform an enormous array of different computations (not necessarily on numbers), all
by detecting nothing but the syntactic features of the symbols and following nothing but the
machine table.
Turing’s Question and the Method for Answering
Can machines think? By thinking or having intelligence, Turing means any system capable of
having BOTH conscious states (states with qualia) as well as intentional states (states with
representational content). Turing attempts to answer in terms of the ‘Imitation Game.’
a. What is the Imitation Game? Draw a diagram, if you want to.
b. Specify at least one problem for the Imitation Game as a test for Intelligence.
Turing on Objections and Replies to Thinking Machines
Turing considers a number of objections to the claim that digital computers can think. For this
section, i) clearly state the objection, ii) explain Turing’s response in your own words, and iii)
evaluate Turing’s response. (Please note that I have omitted several objections.)
a. Argument from Consciousness (p. 445)
i. What is the objection?
ii. What is Turing’s response?
iii. What is your evaluation of Turing’s response?
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b. Arguments from Various Disabilities (p. 447)
alleged disabilities
T’s reponse (not all of the disabilities get the same attention)
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Pick two alleged disabilities you think are the most problematic and explain why you
think T’s response is insufficient.
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Disability 1:
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Disability 2:
c. Lady Lovelace’s Objection (p. 450)
i.
What is the objection?
ii.
What is Turing’s response?
iii.
What is your evaluation of Turing’s response?
d. Argument from Informality of Behavior (p. 452)
i.
What is the objection?
ii.
What is Turing’s response?
iii.
What is your evaluation of Turing’s response?
Positive Evidence for Machine Intelligence.
In the section final section of his paper, “Learning Machines,” Turing points to some positive
evidence that supports the possibility of machine intelligence.
a. What is some of the evidence he lists?
b. What is further evidence you can cite? Remember, Turing wrote this paper in 1950.
There has been enormous progress in computer science and AI.
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