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Lecture 41 of 42 Philosophy of Mind Discussion: Final Exam Review Wednesday, 10 December 2008 William H. Hsu Department of Computing and Information Sciences, KSU KSOL course page: http://snipurl.com/v9v3 Course web site: http://www.kddresearch.org/Courses/Fall-2008/CIS730 Instructor home page: http://www.cis.ksu.edu/~bhsu Reading for Next Class: Chapters 1-14, 22 – 23, 26, Russell & Norvig 2nd edition CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University PHILOSOPHY OF MIND © 2006 Hilary Greaves http://www.rci.rutgers.edu/~hgreaves/teaching/phil103/lectures.htm CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The Two Central Problems in the Philosophy of Mind The Problem of Other Minds How can I know that other minds exist? Thoughts Feelings Sensory experiences etc. Vs. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The Problem of Other Minds (cont’d) How can I know what is going on in other minds? Afraid Looking forward to next summer’s holiday Vs. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The Mind – Body Problem How are minds and their contents related to the physical, chemical & biological world? MIN D CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Two (apparently unique) aspects of mental phenomena Consciousness Your mind is conscious. But as far as we know, ordinary bits of physical matter are not conscious. “What is consciousness?” You know! CONSCIOUS -NESS CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Intentionality (or aboutness) Mental states can be about other things in the world. Your thought that Bush is a jerk is about George Bush. aboutness Bush is a jerk CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Intentionality/aboutness Ordinary physical objects aren’t about anything. The desk is not about the chair. aboutness CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Intentionality/aboutness (A painting can be about something... aboutness CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Intentionality/aboutness ... But that’s only because it was painted by someone who was thinking about the thing he was painting.) aboutness CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Terminological note ‘Intentionality’ has no special connection to intentions. Bush’s knowledge that Saddam Hussein is alive is about Saddam. Tom’s fear of the dentist is about dentists. My desire that Australia will be fun is about Australia. Your intention to eat dinner this evening is about your dinner. Mental states that have ‘aboutness’ (=‘intentionality’) CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Intentionality/aboutness The challenge: an adequate explanation of what minds are should explain how mental goings-on can be about things, since ordinary physical goings-on do not have this feature. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Why explaining ‘aboutness’ is difficult thoughts about things that exist There's no such thing as 'Intentional string'. The asymmetry problem: Aboutness can't be resemblance Bush is a jerk aboutness CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University An attempt to explain what ‘aboutness’ is My thought is about Bush = my thought was ‘caused in the right sort of way’ by Bush. aboutness Bush is a jerk Causal chain CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Why the causal account doesn’t work We can also think about things that don’t exist. It would be fun to ride a unicorn. Causal chain?? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Cartesian Dualism Minds and Matter are two fundamentally different kinds of “substances” Thoughts Feelings Sensory experiences etc. Mental stuff (minds) Consciousness Intentionality Thought Physical stuff (matter) CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems with Cartesian Dualism (I) It's mysterious what the "mind substance" is. What it’s not: Not made of matter Not located in space Not ‘extended’ ... CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems with Cartesian Dualism (II) It’s a mystery how minds can interact causally with things made of matter. Mental causing physical: I’m going to raise my arm. Causes Mental substance (mind) CIS 530 / 730: Artificial Intelligence Matter Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems with Cartesian Dualism (II) Physical causing mental: Sound experienc e Causes sound waves CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems with Cartesian Dualism (III) Are dualism and gradual evolution consistent? ? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems with Cartesian Dualism (IV) It makes the Other Minds problem very hard to solve. Thoughts Feelings Sensory experiences etc. Vs. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University “Materialist” solutions to the Mind – Body Problem Materialism: The claim that everything in the universe is made up of matter. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The advance of materialism The advance of science has made materialism look very plausible to many philosophers & scientists. Astronomy: The heavenly bodies are made of matter and obey the laws of physics. “heavens” earth CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The advance of materialism Evolutionary biology: No non-material processes or forces (e.g. God) are needed to explain the design in the biological world. Spooky stuff? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The advance of materialism Advances in physiology & understanding the genetic code: There is no need for a “life force” ("elan vital"). “life force” Dead tiger Live tiger CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The advance of materialism Advances in understanding the way the brain works – helped by imaging technology – makes it increasingly plausible to believe that mental phenomena like thought and consciousness might be explained in terms of brain processes CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Spooky stuff?? Computing & Information Sciences Kansas State University The “Reductive Materialism” hypothesis The “Reductive Materialism” hypothesis: social sciences can be reduced to (i.e. explained by appeal to) psychology psychology can be reduced to biology biology can be reduced to chemistry chemistry can be reduced to physics CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Behaviorism The way we tell that (e.g.) you're in pain is by observing your behavior. The inspiration for behaviorism: maybe what it means to say you're in pain also involves your behavior. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University ‘Behaviorism’ in psychology Methodological (or: psychological) behaviorists included B. F. Skinner Methodological behaviorism: If there is anything more to mental states than dispositions to behave in certain ways, that 'extra bit' has nothing to do with science. I am feeling angry CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University ‘Behaviorism’ in philosophy Analytical (or: philosophical) behaviorists included Ludwig Wittgenstein and Gilbert Ryle: there is nothing more. I am feeling angry EQUALS CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Analytical behaviorism Analytical behaviorism: Claims about mental states and processes can be “translated” into claims about patterns of behavior. Example: “Tom has a toothache” = “Tom moans; Tom says his tooth hurts; if someone touches Tom’s tooth, Tom screams; etc." CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Analytical behaviorism “Jenny is hungry” = ?? “Jason wishes he could quit school” = ?? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Behaviorism and the Problem of Other Minds I am feeling angry EQUALS CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems for behaviorism (I): Undefinable mental states Some mental states don't seem to be definable in this way. Listening to Bob Dylan Thinking about how big the universe is CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems for behaviorism (II): Circular definitions Behaviorist “definitions” of mental state terms all turned out to be circular (or just plain wrong). ‘Tom believes it will rain today’ = ‘Tom will either stay at home or drive to school today’ IF Tom wants to stay dry, and Tom doesn’t believe there’s a shelter at the bus stop, and... CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems for behaviorism (II): Circular definitions “James believes the exam will be hard” = ....?? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems for behaviorism (III): The 'inverted spectrum' problem It seems possible for one person to have their spectrum of color experiences 'inverted' relative to another's. But according to behaviorism, this is not possible. The flower looks yellow The flower looks yellow CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems for behaviorism (IV): Some wrong predictions For behaviorists, two people who behaved in just the same way would have the same mental states. But there are cases in which this is clearly crazy. Dennett’s thought experiment: curare plus “amnestic” Administer general anaesthetic “How did it feel?” operation CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problems for behaviorism (IV): Some wrong predictions “Curare”: paralyses all voluntary muscles “Amnestic”: Has no effect until 2 hours after ingestion, whereupon it wipes out memory of those two hours Administer curare + amnestic “How did it feel?” operation CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University ... The problem (an argument against behaviorism): (P1) Behaviorism predicts that the patient who is given general anaesthetic has the same experiences as the patient who is given curare + amnestic. (P2) But that’s wrong! One is unconscious, and the other is in excruciating pain. Therefore, (C) Behaviorism is false. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The (Type-Type) Identity Theory The type – token distinction the the Greaves's belief that snow is white & your belief that snow is white. Snow is white CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Snow is white Computing & Information Sciences Kansas State University The (Type-Type) Identity Theory The type-type identity theory: Mental state types are identical with brain state types Examples of mental state types: the belief that snow is white a burning pain in the index finger the thought that 17 is a prime number Example of a type-type identification: "Pain is c-fibers firing" pain Same event (type) CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University How the theory deals with the Other Minds Problem ..?? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Problem for the (Type) Identity Theory: “Chauvinism” about the mental According to type-type identity theory: Animals with brains significantly different from ours can’t feel pain or have other mental states If there are organisms in the universe whose chemical composition is different from ours, they can’t feel pain or pleasure, and they can’t think. pain Extra-terrestrials can’t even think about math. 7x5=35 CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Functionalism (aka “machine functionalism”) The emergence of computers and the computer model of the mind. Computers are symbol manipulators Programs specify how the symbols are to be manipulated. 2 5 3 CIS 530 / 730: Artificial Intelligence ADDING PROGRAM Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Programs and physical devices Many different sorts of physical devices can run the same program... CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Minds and programs Minds are to brains as programs are to computers “The mind is the brain’s program” PROGRAM Inputs (mouse clicks, keyboard strokes) Outputs (screen displays; printouts) PROGRAM Outputs (body movements; screams; sentences spoken) Inputs (light rays; hammers hitting thumb) CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University ‘Functional states’ Mental state concepts are functional concepts; mental states are functional states (not physical states) ‘Functional states’ for the adding program: Input 2 Computer state: ‘ready to do an add calculation’ Input 3 Computer state: ‘remember that a 2 has been input, and get ready to add a 2nd number’ Output 5 Functional states CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University ‘Functional states’ cont’d Input: See that it’s raining Functional states Desire to stay dry Belief that it’s raining Output: Look for car keys Belief that there is no shelter at the bus stop CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University What is... The functionalist solution to the Other Minds Problem? The functionalist solution to the chauvinism problem? pain ? pain ? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Strong AI A radical (?) implication of functionalism: “Strong AI” -- It is possible to build artificial minds with real mental states. A computer running the same program that your brain is running would have the same mental states that you have. It would be conscious, and thus feel pains and pleasures, have emotions, etc. It would have thoughts with real intentionality. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Can machines think? If they can, then the fact that functionalism predicts that they can counts in favor of the functionalist theory. If not, it counts as an objection to functionalism. The Turing test – if a machine passes the Turing test, we cannot tell that it isn't really thinking It is a further step to say that if a machine passes the Turing test, then it is thinking. But perhaps (?) this extra step is very plausible. “What do you think about Saddam’s trial?” “I don’t normally approve of the death penalty, but this guy deserves everything he gets.” CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Searle’s Critique of Functionalism and Strong AI Roger Schank’s project: Getting a computer to understand stories and answer questions about them the way people do. Did the man eat the hamburger? A man went into a restaurant and ordered a hamburger. When the hamburger arrived it was burnt to a crisp, and the man stormed out of the restaurant angrily, without paying for the burger or leaving a tip. CIS 530 / 730: Artificial Intelligence No Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University What Schank’s computer is doing It’s manipulating symbols. Does this mean that it understands what the symbols mean (i.e. understands the story, and understands its replies to the questions)? Thinking of a restaurant scene CIS 530 / 730: Artificial Intelligence aboutness Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Searle’s argument Understanding is an ‘intentional state’ – when you understand a story, you understand what it is about. Searle’s going to argue that the computer could be manipulating symbols in all the right ways, without understanding the story (= without having ‘intentionality’). The "Chinese room argument": An argument that passing the Turing test is not sufficient or thinking. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University The setup of the "Chinese room” Input: CIS 530 / 730: Artificial Intelligence Output: Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Searle’s argument (P1) Neither Searle nor any other part of the Chinese Room really understands Chinese. Therefore, (C1) The Chinese Room [i.e. the system] does not understand Chinese. (From (P1)) (P2) But the Chinese Room perfectly simulates someone who does understand Chinese. Therefore, (C2) Simulating understanding is not sufficient for having understanding. (From (P2), (C1)) Therefore, (C3) Even if Schank's computer perfectly simulates human understanding of stories, it does not follow that Schank's computer really understands stories. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Searle’s Account of Intentionality It is a “causal product” of the right kind of biological system. adding Not a “causal product” of the symbol manipulation 2 5 3 CIS 530 / 730: Artificial Intelligence ADDING PROGRAM Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Searle’s Account of Intentionality Window breaks Pick up brick and throw at window CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Causal product of brick being thrown Computing & Information Sciences Kansas State University Searle’s Account of Intentionality Searle’s Account of Intentionality It cannot be created simply by symbol manipulation. Searle makes the same claims for consciousness. intentionalit y intentionalit y ??? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University A Problem for Searle’s View Either intentionality and consciousness are restricted to brains like ours in which case he is committed to chauvinism Or brains quite different from ours can also produce intentionality & consciousness in which case the Other Minds Problem looks to be unsolvable since we can’t tell which brains just simulate consciousness & intentionality & which really have it. CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Some questions for YOU to ponder Can a suitably sophisticated computer which is NOT made out of “meat” like the human brain have real intentionality (and thus real thoughts)? have real consciousness (feel real pain & pleasure, and know what it is like to experience colors & tastes)? Does it matter? If so, why? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University Some questions for YOU to ponder Can an extra-terrestrial with a suitably sophisticated brain that is very different from our brain have real intentionality (and thus real thoughts)? have real consciousness (feel real pain & pleasure, and know what it is like to experience colors & tastes)? How can we KNOW whether the computer or the extra-terrestrial has REAL consciousness and REAL intentionality? CIS 530 / 730: Artificial Intelligence Wednesday, 10 Dec 2008 Computing & Information Sciences Kansas State University