The Turing Test

1
The Turing Test

• Computing Machinery and Intelligence
• Alan Turing

2
Some Theories of Mind

• Dualism
• Substance Dualism mind and body are differerent
  substances. Mind is unextended and not subject to
  physical laws.
• Interactionism mind and body interact
• Occasionalism/Parallelism mind and body dont
  interact
• Property/Event Dualism
• Epiphenomenalism physical events cause mental
  events but mental events dont cause anything
• Property Dualism(some) mental states are
  irreducibly non-physical attributes of physical
  substances

3
Some Theories of Mind

• Physicalism mental states are identical to
  physical states, in particular, brain states or,
  minimally, supervene upon physical states.
• (Analytical or Logical) Behaviorism talk
  about mental states should be analyzed as talk
  about behavior and behavioral dispositions
• The Identity Theory (Type-Physicalism) mental
  states are identical to (so nothing more than)
  brain states
• Functionalism mental states are to be
  characterized in terms of their causal relations
  to sensory inputs, behavioral outputs and other
  mental states, that is, in terms of their
  functional role.

4
Dualism(s)

• Pro
• Qualia
• Irreducibility of psychology
• The Zombie Argument
• The Cartesian Essentialist Argument

• Con
• Causal closure of the physical
• Simplicity

5
Descartes Arguments for Dualism

• Essentialist Argument
• It is conceivable that ones mind might exist
  without ones body
• Whatever is conceivable is logically possible
• Therefore, it is possible ones mind might exist
  without ones body
• Empirical Argument
• The complexity and flexibility of human behavior,
  including linguistic behavior, couldnt be
  achieved by mere mechanism so we need to assume
  some non-physical substance as an explanation for
  such behavior.

6
The Zombie Argument

• A (philosophical) zombie is a being which is a
  perfect duplicate of a normal human
  beingincluding brain and neural activitybut
  which is not conscious.
• The Zombie Argument for property dualism
• Zombies are conceivable (David Chalmers singing
  the Zombie Blues)
• Whatever is conceivable is logically possible
• (Some) mental states/properties/events are not
  identical to any brain states/properties/events
• Note this argument doesnt purport to establish
  substance dualism or, as Descartes wished to
  show, that minds/persons could exist in a
  disembodied state.

7
Problem with Cartesian Dualism

• We do not need that hypothesis complex
  behavior can be explained without recourse to
  irreducibly non-physical states.
• Contra Descartes, purely physical mechanisms can
  exhibit the kind of complex, flexible behavior,
  including learning (or learning) characteristic
  of humans.
• All physical events have sufficient causes that
  are themselves physical events
• Physicalism is an aggressor hypothesis we
  explain more and more without recourse to
  non-physical events/states
• Agency explanations are eliminated in favor of
  mechanistic explanationsincluding explanations
  for agency itself.
• Claims to the effect that non-physical events
  cause physical events introduces an even bigger
  mystery what is the mechanism?

8
Epiphenomenalism

• Motivation for Epiphenomenalism
• All physical events have sufficient causes that
  are themselves physical events
• But some mental eventsqualitative states, the
  what-it-is-like experienceseem to be irreducibly
  nonphysical it seems implausible to identify
  them with brain events.
• Problem intuitively some mental states cause
  behavior
• E. g. pain causes people to wince
• Moreover, part of what we mean by pain seems to
  involve an association of with characteristic
  behavior
• Well leave association intentionally vague

9
(Philosophical) Behaviorism

• Motivation
• We want to hold that there are no irreducibly
  non-physical causes of physical events
• But we also need to accommodate the fact that
  what we mean by terms designating mental states
  involves an association with characteristic
  behavior.
• Problems
• Intuitively, theres more to some mental states
  the problem of qualia
• Intuitively, there can be less to mental states
  its conceivable that one may be in a given state
  without even being disposed to characteristic
  behavioror that one may be disposed to
  uncharacteristic behavior
• Dispositions arent causes so, while behaviorism
  associates mental states with behavior, they
  still dont cause behavior.

10
The Identity Theory

• Motivation
• We want to hold that there are no irreducibly
  non-physical causes of physical events
• But we also want to understand them as inner
  states that are causally responsible for
  behavior
• Problems
• Qualia again intuitively there is more to
  consciousness than brain states
• Species chauvinism if we identify a type of
  mental state, e.g. pain, with a type of brain
  state that is responsible for pain in humans,
  e.g. the firing of C-fibers, what do we do about
  non-humans who dont have the same kind of brain
  states but who, we believe, can never the less
  have the same kind of mental states?

11
What a theory of mind should do

• Make sense of consciousness The Hard Problem
• Avoid commitment to irreducibly non-physical
  states, events or substances
• Explain the causal role of mental states as
• Effects of physical events
• Causes of behavior
• Causes of other mental events
• Allow for multiple realizability in order to
  avoid species chauvinism
• We want to be able to ascribe the same kinds of
  mental states we have to humans who may be wired
  differently, other animals and, possibly to
  beings that dont have brains at all, e.g.
  Martians, computers

12
Functionalism

• What makes something a mental state of a
  particular type does not depend on its internal
  constitution, but rather on the way it functions,
  or the role it plays, in the system of which it
  is a part.
• Note function here related also to function
  in math sense.
• Topic Neutrality mental state concepts dont
  specify their intrinsic character, whether
  physical or non-physicalthats a matter for
  empirical investigation.
• So Functionalism is in principle compatible with
  both physicalism and dualism
• Multiple Realizability A single mental kind
  (property, state, event) can be "realized" by
  many distinct physical kinds.
• The same type of mental state could, in
  principle, be realized by different physical
  (or non-physical) states
• Disagreement about how liberal we should be in
  this regard

13
An Example Pain

• Were interested in analyzing or ordinary concept
  of pain
• We understand it in terms of its causal role
• As being typically produced by certain stimuli,
  e.g. bodily injury
• As tending to produce certain behavior, e.g.
  wincing
• As producing further mental states, e.g.
  resolving to avoid those stimuli in the future
• We recognize that different kinds of physical (of
  non-physical) mechanisms may play that role
• Compare to other functional concepts like can
  opener
• We leave empirical questions to empirical
  investigation

14
The Big Questions About Functionalism

• Consciousness some mental states appear to have
  intrinsic, introspectable featuresand those
  features seem to be essential
• Inverted Qualia (see Block Inverted Earth)
• Zombies
• The Knowledge Argument (see Jackson What Mary
  Didnt Know)
• Understanding controversial whether
  understanding can be reduced to the ability to
  mediate input and output by manipulating symbols
  (see Turing Computing Machinery and
  Intelligence vs. Searle on The Chinese Room

15
The Turing Test

• Functionalism mental states are to be
  characterized in terms of their causal relations
  to sensory inputs, behavioral outputs and other
  mental states, that is, in terms of their
  functional role.
• A Turing Machine can do this!
• So if Functionalism is true, a machine should in
  principle be able to do anything a person can do
• Can a machine do whatever a person can do?
• And can it meet

16
The Cartesian Challenge

• If there were machines which bore a resemblance
  to our bodies and imitated our actions as closely
  as possible for all practical purposes, we should
  still have two very certain means of recognizing
  that they were not real men. The first is that
  they could never use words, or put together
  signs, as we do in order to declare our thoughts
  to others. For we can certainly conceive of a
  machine so constructed that it utters words, and
  even utters words that correspond to bodily
  actions causing a change in its organs. But it
  is not conceivable that such a machine should
  produce different arrangements of words so as to
  give an appropriately meaningful answer to
  whatever is said in its presence, as the dullest
  of men can do. Secondly, even though some
  machines might do some things as well as we do
  them, or perhaps even better, they would
  inevitably fail in others, which would reveal
  that they are acting not from understanding, but
  only from the disposition of their organs. For
  whereas reason is a universal instrument, which
  can be used in all kinds of situations, these
  organs need some particular action hence it is
  for all practical purposes impossible for a
  machine to have enough different organs to make
  it act in all the contingencies of life in the
  way in which our reason makes us act. Descartes
  Discourse on Method

17
What can people do that computers cant do?

• Telling Humans and Computers Apart Automatically
• A CAPTCHA is a program that protects websites
  against bots by generating and grading tests that
  humans can pass but current computer programs
  cannot. For example, humans can read distorted
  text as the one shown below, but current computer
  programs can't
• The term CAPTCHA (for Completely Automated Public
  Turing Test To Tell Computers and Humans Apart)
  was coined in 2000 by Luis von Ahn, Manuel Blum,
  Nicholas Hopper and John Langford of Carnegie
  Mellon University.

18
Empirical and Conceptual Questions

• The Turing Test Can a machine meet the
  Cartesian challenge?
• Use language in a way that humans do rather than
  merely uttering sounds?
• Exhibit the complexity and flexibility of
  behavior in a wide range of areas as humans do?
• What, if anything, of philosophic interest would
  it show if a machine could pass the Turing Test?
• Is passing the test necessary for intelligence?
• Is passing the test sufficient?
• What is a machine? Arent our brains
  themselves machines?

19
Some Chatbots

• Eliza
• Alice
• Suzette
• Jack the Ripper
• POMO generator
• Poetry generator
• ChatbotCollection

WFF
20
The Babbage Engine
21
ENIAC
22
Build your own Turing Machine!
A Turing machine is a theoretical computing
machine invented by Alan Turing (1937) to serve
as an idealized model for mathematical
calculation. A Turing machine consists of a line
of cells known as a "tape" that can be moved back
and forth, an active element known as the "head"
that possesses a property known as "state" and
that can change the property known as "color" of
the active cell underneath it, and a set of
instructions for how the head should modify the
active cell and move the tape (Wolfram 2002, pp.
78-81). At each step, the machine may modify the
color of the active cell, change the state of the
head, and then move the tape one unit to the left
or right.read more in Wolfram MathWorld
23
A Turing Machine is an Abstract Machine

• An abstract machine is a model of a computer
  system (considered either as hardware or
  software) constructed to allow a detailed and
  precise analysis of how the computer system
  works. Such a model usually consists of input,
  output, and operations that can be preformed (the
  operation set), and so can be thought of as a
  processor. An abstract machine implemented in
  software is termed a virtual machine, and one
  implemented in hardware is called simply a
  "machine.Wolfram Mathworld
• Turing Machine here try it!
• Another Turing Machine
• A concrete Turing Machine

24
Different hardware same abstract machine
Were in the same computational state!
Were in the same computational state!

• Mental states are like computational states of
  computers
• The same computational or mental state can be
  realized by different hardware or brainware!

25
The Imitation Game

• Turing proposes a game in which we have a
  person, a machine, and an interrogatorseparated
  from the other person and the machine.
• The object of the game is for the interrogator to
  determine which of the other two is the person,
  and which is the machine.
• I believe that in about fifty years time,
  Turing wrote in 1950, it will be possible to
  programme computersto make them play the
  imitation game so will that an average
  interrogator will not have more than 70 chan ce
  of making the right identification after five
  minutes of questioningI believe that at the end
  of the century the use of words and general
  educated opinion will have altered so much that
  one will be able to speak of machines thinking
  without expecting to be contradicted.
• So far this hasnt happened butthere is a
  contest on

26
The Empirical Question Can a machine pass?

• The Loebner Prize In 1990 Hugh Loebner agreed
  with The Cambridge Center for Behavioral Studies
  to underwrite a contest designed to implement the
  Turing Test. Dr. Loebner pledged a Grand Prize of
  100,000 and a Gold Medal (solidnot
  gold-plated!) for the first computer whose
  responses were indistinguishable from a human's.

27
The Conceptual (Philosophical) Question

• If the meaning of the words machine and
  think are to be found by examining how they are
  commonly used it is difficult to escape the
  conclusion that the meaning and the answer to the
  question, Can machines think is to be sought in
  a statistical survey such as a Gallup poll. But
  this is absurd. Instead of attempting such a
  definition I shall replace the question by
  another, which is closely related to it and is
  expressed in relatively unambiguous words.
• How is the question (of whether a machine could
  pass the Turing Test) related to the question of
  whether a machine can think?
• What would it show if a machine could pass the
  Turing Test?
• Is being able to pass the Turing Test a necessary
  condition on intelligence?
• Is being able to pass the Turing Test a
  sufficient condition on intelligence?

28
Behaviorism?

• The new problem has the advantage of drawing a
  fairly sharp line between the physical and
  intellectual capacities of a man. No engineer or
  chemist claims to be able to produce a material
  which is indistinguishable from the human
  skinbut even supposing this invention available
  we should feel there was little point in trying
  to make a thinking machine more human by
  dressing it up in such artificial flesh.
• What matters for intelligenceor whatever
  Turing is testing for?
• Does the right stuff (brain-stuff, spiritual
  substance, or whatever) matter?
• Does the right internal structure or pattern of
  inner workings matter? If so, at what level of
  abstraction?
• Does the right history, social role or
  interaction with environment beyond interrogation
  and response in the Turing Test matter?

29
Objections Turing Considers

1. The Theological Objection
2. The Heads in the Sand Objection
3. The Mathematical Objection
4. The Argument from Consciousness
5. Arguments from Various Disabilities
6. Lady Lovelaces Objection
7. Argument from Continuity in the Nervous System
8. Argument from the Informality of Behavior
9. Argument from Extrasensory Perception

30
The Theological Objection

• Thinking is a function of mans immortal soul.
  God has given an immortal soul to every mabn and
  women, but not to any other animal or to
  machines. Hence no animal or machine can think.
• Turings response God could give a machine a
  soul if he wanted to
• Some questions
• Zombies. On this account it would be a contingent
  fact that intelligent computers (or humans) had
  soulssoulless zombies could perfectly simulate
  ensouled humans or machines.
• Are souls, if there are such things, what matter
  for consciousness (vide Locke)

31
The Heads in the Sand Objection

• The consequences of machines thinking would be
  too dreadful. Let us hope and believe that they
  cannot do so.
• Turing notes that theres no real argument here.
• Nevertheless, the prospect of intelligent
  machines raises a number of ethical questions

32
The Mathematical Objection

• Gödels theoremshows that in any sufficiently
  powerful logical system statements can be
  formulated which can neither be proved nor
  disproved within the system.
• Consequently there will be some questionsa
  machine (being essentially an automatedformal
  system) cannot answer.
• Turing notes however that there arequestions
  that humans cant answerand it could be that
  beyond this werebound by the same constraint
  that restrictsthe capacity of machines.

33
The Argument from Consciousness

• No mechanism could feel (and not merely
  artificially signal, an easy contrivance)
  pleasure at its successes, grief when its valves
  fuse, be warmed by flattery, be made miserable by
  its mistakes, be charmed by sex, be angry or
  depressed when it cannot get what it wants.
• A machine that passed the Turing Test would, ipso
  facto, be able to give appropriate responses to
  questions about poetry, emotions, etc.
• If we require more than the Turing Test as
  evidence of consciousness then we have no good
  reason to believe that other humans are
  conscious.
• But we do have good reason to believe that other
  humans are conscious.
• Therefore the Turing Test would be evidence of
  consciousness in a machine if that machine could
  pass the test.

34
Arguments from Various Disabilities

• These arguments take the form, I grant you that
  you can make machines do all the things you have
  mentioned but you will never be able to make one
  tobe kind, be resourceful, be beautiful, be
  friendly, have initiative, have a sense of humor,
  tell right from wrong, make mistakes, fall in
  love, enjoy strawberries and cream, make someone
  fall in love with it, learn from experience, use
  words properly, be the subject of its own
  thought, have as much diversity of behavior as a
  man, do something really new.
• It seems likely that we can construct machines
  that will be able to do a great many of these
  thingsincluding learning and making mistakes but
• We should also ask whether various items on the
  list are requirements for intelligence or whether
  were building in a species-chauvinistic
  requirement that would exclude intelligent beings
  that arent like us humans.

35
Lady Lovelaces Objection

• The Analytical Engine has no pretensions to
  originate anything. It can do whatever we know
  how to order it to perform
• But computers can surprise us and
• People arent all that original anyway

36
Final Objections

• Argument from Continuity of the Nervous System
• Response a digital machine can imitate an
  analogue machine
• Argument from the Informality of Behaviour
• Response no reason to think human behavior is
  any less rule-governed
• Argument from Extrasensory Perception
• Taking ESP seriously, we could find ways to rule
  it out by putting competitors in a
  telepathy-proof room. Surely, even if ESP were
  a reality it wouldnt be any more of a
  requirement for intelligence than the ability to
  appreciate strawberries and cream.
• Learning
• In fact computers can, at least learn and,
  unless weve established independently that they
  arent intelligent, no reason to deny that this
  constitutes genuine learning.

37
Imitation and Replication

• When is imitating X replicationi.e. another
  instance of Xrather than mere simulation?
• When does the right stuff matter
• Margerine is only simulated butter but
• Walking with an artificial leg is real walking
• When do the right extrinsic features, e.g. right
  history matter
• Counterfeit money and art forgeries are fakes but
• A copy of a file or application is the real thing

38
Are inputs/outputs all that matter?

• Consider, for example, Ned Block's Blockheada
  creature that looks just like a human being, but
  that is controlled by a game-of-life look-up
  tree, i.e. by a tree that contains a programmed
  response for every discriminable input at each
  stage in the creature's life. If we agree that
  Blockhead is logically possible, and if we agree
  that Blockhead is not intelligent (does not have
  a mind, does not think), then Blockhead is a
  counterexample to the claim that the Turing Test
  provides a logically sufficient condition for the
  ascription of intelligence. After all, Blockhead
  could be programmed with a look-up tree that
  produces responses identical with the ones that
  you would give over the entire course of your
  life (given the same inputs).

39
Objections to the Turing Test as What Matters

• Intentionality (The Chinese Room Searle, Minds,
  Brains and Programs)
• You cant crank semantics out of syntax mere
  symbol-manipulation, however adept, doesnt
  create meaning or understanding.
• Consciousness (The Inverted Spectrum Block,
  Inverted Earth)
• Neither behaviorism nor functionalism can capture
  the felt, intrinsic character of phenomenal
  mental states, e.g. what it is like to see red.
• Semantic Externalism (Swampman Davidson,
  Knowing Ones Own Mind)
• What one's words meanif they meanis determined
  not merely by some internal state, but also by
  the causal history of the speaker and the role he
  plays within his environment.

40
Intentionality Objection

• What does CKApqrr mean? According to the
  syntactic rules of the first game, Shak-A-WFF,
  its a WFF but when I construct and manipulate
  WFFs I dont know what Im doing.

41
Consciousness the Inverted Qualia Objection

• The inverted spectrum argument is this when
  you and I have experiences that have the
  intentional content looking red, your qualitative
  content is the same as the qualitative content
  that I have when my experience has the
  intentional content of looking green.
• We use color words in the same way, make the
  same inferences, and respond in the same way to
  the same stimuli but (it seems to be conceivable
  that) our experiences are different in their
  intrinsic, qualitative character what it is
  like to see red is different from what it is
  like for me. The Turing Test cant capture the
  what it is like feature of experience.

42
Semantic Externalism
43
Consciousness The Zombie Problem

• It seems conceivable that a being with NO qualia
  could pass the Turning Test. Do qualia matter? If
  so, for what?