Philosophy 4610 Philosophy of Mind Week 9: Computer Thinking (continued)

Blade Runner : (Do Androids Dream of Electric Sheep?) ► The year is 2019 ► Deckard (Harrison Ford) is a “Blade Runner” – an elite cop trained to find and hunt down human-like androids or “replicants” ► Six replicants have escaped from a prison colony and are causing problems

Blade Runner: The Voight-Kampf Test ► In order to tell whether a subject is human or a replicant, investigators use a complex test called the “voight-kampf” test to evaluate their responses and reactions ► Some of the newest generation of replicants have been designed to give emotional responses and have even been implanted with “false memories” so that they themselves do not know they are not human.

Blade Runner ► If you were Deckard and were confronted with a tricky subject who might be a Replicant, what questions would you want to ask him? ► How could you know for sure whether your subject was human or not? Could you know for sure?

The Turing Test: Questions and Objections ► Is there anything essential that a human being can do that a computer could never do? Why? ► Even if a computer can pass a Turing test, how do we know it is really thinking as opposed to imitating or simulating thought? ► If the Turing test is not a good test for actual thinking, is there any better test?

Computer Thinking: Objections 1) The Theological Objection: “Thinking is a function of man’s immortal soul. God has given an immortal soul to every man and woman, but not to any other animal or to machines. Hence no animal or machine can think.” (p. 5) Response: 1) If God can create bodies and attach souls to them, he could also attach souls to computers 2) Theological arguments are unsatisfactory for establishing scientific conclusions

Computer Thinking: Objections 2) The “Heads in the Sand” Objection: “The consequences of machines thinking would be too dreadful. Let’s hope and believe that they cannot do so.” (p. 6) Response: This is not really an argument at all, but just an appeal for consolation.

Computer Thinking: Objections 4) The Argument from Consciousness: “No machine could feel (and not merely artificially signal...) 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.” (Geoffery Jefferson, 1949 (P. 6)) Response: If it is impossible to know that a machine is really conscious judging from its responses, then it is impossible to know whether any other person is really conscious as well. If the Turing test could not show that a computer is really thinking, then it is impossible for me to show that anyone else (other than myself) is really thinking.

Computer Thinking: Objections 5) Arguments from Various Disabilities: No computer could ever do X (where X is, e.g. “Be kind, resourceful, beautiful, friendly, have initiative, have a sense of humour, tell right from wrong, make mistakes, fall in love, enjoy strawberries and cream, make some one fall in love with it, learn from experience, use words properly, be the subject of its own thought, have as much diversity of behaviour as a man, do something really new.” (p. 8) Response: Various, but all of these seem to be based on a bad extrapolation from what we have seen before. Some of the computers we have seen cannot do these things, but that is no reason to think we could not eventually build a computer that can.

Computer Thinking: Objections 6) Lady Lovelace’s Objection: Computers only do what they are programmed to do, so it is impossible for a computer ever to learn something new or do something unexpected Response: Computers do “new” and surprising things all the time. It is also easily possible for us to set up a mechanism whereby a computer can modify its own program, and thereby can be said to have “learned.”

Computer Thinking: Minds and Machines ► “The ‘skin-of-an-onion analogy is also helpful. In considering the functions of the mind or brain we find certain operations which we can explain in purely mechanical terms. This we say does not correspond to the real mind: it is a sort of skin which we must strip off to find the real mind. But then in what remains we find a further skin to be stripped off, and so on. Proceeding in this way do we ever come to the ‘real’ mind, or do we eventually come to the skin which has nothing in it? In the latter case the mind is mechanical.” (Turing, p. 12)

Artificial Intelligence: Identifying the positions ► Can a computer think? ► Is passing the Turing test a sufficient criterion for a computer thinking? ► What do you think each of the positions (dualism, logical behaviorism, identity theory, functionalism) we studied in the first half of the course would say to each question?

John Searle and the ‘Chinese Room’ ► Searle argues against both functionalism (the computer model of mind) and the claim that a computer that passes the Turing test would actually be thinking. ► He does so by using a counter-example wherein a system passes the Turing test, but is not at all thinking or understanding.

Searle and “Strong AI” ► “Strong AI” can be defined as the position that:  I) A computer that is programmed with rules for the manipulation of symbols can actually think  II) We can tell that such a system is actually thinking if it can pass the Turing test. ► Searle’s “Chinese Room” example is meant to refute both claims

The “Chinese Room”

The Chinese Room ► In the Chinese Room, there is a rule book for manipulating symbols and an operator who does not understand any Chinese ► The Room produces perfectly good Chinese answers and could pass a Turing Test conducted in Chinese ► But nothing in the room actually understands Chinese

The Chinese Room ► According to Searle, in the Chinese Room there is intelligent-seeming behavior but no actual intelligence or understanding. There is syntax (rules for the manipulation of meaningless signs) but the semantics or meaning of the signs is missing. This shows, Searle argues, that rule-governed behavior is not enough to give real understanding or thinking.

The Chinese Room: The “Systems” Reply ► Even if there is no single element in the Chinese Room that understands Chinese, perhaps the understanding of Chinese really is in the whole system itself. ► What are the criteria for “really understanding” as opposed to just seeing to understand? What role (if any) does experience, consciousness, or self-awareness play? How might we test for these qualities?

Computer Thinking: Summary ► Turing suggested that computers could think and he suggested the Turing test to determine whether they can think. ► If we accept the test, it will be difficult to hold onto a dualist or theological view of human consciousness ► On the other hand, it is not obvious how to explain consciousness or the possibility of a physical organism giving rise to experience at all