Why Are Computers So Dumb? Philosophy of AI. Are They Right? What Makes us Human? Strong and Weak AI. Weak AI and the Turing Test

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1 Why Are Computers So Dumb? Philosophy of AI Will Machines Ever be Intelligent? AI has made some pretty small strides! A huge number crunching computer beat Kasparov at chess (once) but it still wouldn t find the Simpsons funny Is it just because they lack the scope of knowledge and experience? Or are the current techniques woefully inadequate? Or is there something inherent about human intelligence that a computer could never have? 1 of 33 2 of 33 What Makes us Human? General arguments against the idea that computers might ever be intelligent like humans cover: Emotions play a large part in human intelligence Human creativity could never be artificially simulated Computers could never be conscious Human mental life is not computable 3 of 33 Are They Right? Interestingly, the aspects of human mental life that we understand the least are the ones that people use against AI Consciousness, for example, is not at all understood, so how could we build it into a computer? Then again, how can we say that a computer couldn t have it, if we don t know what it is And then there is free will. Can computers have it? Do we have it? Hmm, tricky. 4 of 33 Strong and Weak AI Two definitions before we go on: Weak AI That computers could seem (or act like they are) intelligent Strong AI that computers could actually BE intelligent like (or better than) humans, and be aware of themselves and their intelligence Weak AI and the Turing Test Alan Turing suggested that worrying about internal experience is not necessary, and anything that can act intelligently can be said to be intelligent By intelligently, he meant, in a way that is indistinguishable from a human So, could a computer fool us into thinking it is human? 5 of 33 6 of 33 1

2 The Turing Test Imagine you moderating an internet chat room, where two people are talking. You know one is a young girl and the other an old man pretending to be a young girl. Can you tell which is which? If not, the old man has passed a version of the Turing test. Now imagine it s not an old man at all, the chat is generated by a computer. If it can fool you into thinking it is a human, then it has passed the Turing test. What is Being Tested? The Turing test is a test of weak AI the computer needn t be conscious to pass, just act like it is. Ability to imitate, or fool, rather than be intelligent show human traits, not computational power So is it a good test? Well, it has generated a lot of thought and argument, but has now been largely abandoned as anything other than an interesting thought experiment 7 of 33 8 of 33 Questions Raised by Turing s Test If the Turing test is not a very good test of intelligence, then why is it so famous? It raises a lot of interesting questions, many of which Turing addressed in the original 1950 paper on the subject. Turing listed 9 objections that people might make against the idea that computers could ever be intelligent. He also provided his responses to them. 1. Theological Objection That humans have a (God given?) spirit, soul, mind, free will, something, that is not physical This mind allows us to be conscious and intelligent Computers don t have one, so they can t be intelligent This is known as the dualist argument 9 of of 33 Dualism Dualists believe that the mind is somehow separate from the body (or the brain) The mind forms part of our mental life it causes thinking It has also been argued that the mind causes consciousness and free will The existence of free will is hotly debated, as is dualism One problem: how does the non-physical mind affect the physical body? 2. Heads in the Sand Argues that the consequences of computers becoming as (or more) intelligent that us are terrible and so we shouldn t try to build them More of a reason why we shouldn t than why we couldn t Back then, the Terminator movies hadn t been made, either 11 of of 33 2

3 3. Mathematical Objection We have some understanding of the limits of computation Logic, maths, and algorithms are formal systems capable of performing a set of defined tasks those performable by a Turing machine (or equivalent) The mathematical object states that human intelligence requires something outside such formal systems and computers can t escape the Turing machine limitations 13 of 33 Gödel s Theorem The mathematician, Gödel, proved that no formal system (and that includes all computers) can be both consistent and complete That means that any formal system (except the most simple) must either: Contain a truth that cannot be proved within the system, even though it is clearly true Or contain an inconsistency a statement that is both true and false 14 of 33 Gödel Example This statement is false Is it true, or false, or neither, or both? A moment s thought, and as a human, we can understand the status of that sentence If you tried to put it into a propositional logic based agent, it would break it! Humans don t get fooled like this, so we can t be formal systems! (Goes the argument) 15 of 33 Are Human Minds Formal Systems? Nobody knows We can deal with inconsistency and contradiction Perhaps there is some unknowable question that is the Gödel sentence for the human mind what would happen if we ever found it? Can we know something to be true, even if our brains can t formally prove it? 16 of Consciousness The consciousness argument says that computers must really feel emotions, and know they are feeling them, and know that those emotions apply to themselves This argument is pertinent to the strong AI claim, but not the weak one, so a machine could pass the Turing test and not be conscious However, Turing addressed this issue anyway Can Machines be Conscious? How would we ever know? A machine might claim to be conscious when it is not Are dogs conscious? Mice? Worms? How do you know that I am? The only way to prove a being really feels emotions and doesn t just emulate them is to be that being Relates to dualism, is consciousness an emergent property of the physical brain? 17 of of 33 3

4 Chinese Room The Philosopher John Searle made a similar objection using his Chinese Room argument Armed with a pile of card with Chinese symbols printed on it and a filing cabinet full of rules telling you which cards to show in response to cards shown to you, you could appear to understand Chinese You wouldn t understand Chinese no more than a computer understands the rules it follows Problems with the Chinese Room Symbols don t have meaning unless they are connected to the thing in the world they represent Connect the cards to the man s daily experience and he has learned a foreign language, which he understands If we have something extra that connects the symbols in our heads to the world, what is it? Back to dualism. 19 of of Various Disabilities Perhaps the most common set of layman's objections to AI Computers can never: Fall in love Create true art Learn from experience Feel sympathy for others Some of the items in the list have been achieved learning for example Illogical Human Activity There is an idea that creativity and emotions are separate from logic, and that they are not governed by rules Computers are governed by rules Therefore, computers cannot be creative Seems a terribly logical argument for such an emotive point of view 21 of of 33 Is Creativity Rule-Free? There is a cliché with some truth in it that creativity is about knowing when to break the rules But if there is a right time to break the rules, there must be a rule for when to do it All you have is a bigger set of rules. What else is there, other than rules? Randomness? 23 of 33 The Great Musical Genetic Algorithm If a computer wrote a million songs a day and somehow played them to people who said whether or not they liked them, And it then wrote more songs like the popular ones, and fewer like the unpopular ones, It could develop a model of what people liked so that after a while it could write a new song, judge it with the model, and know whether it was good or not. Perhaps that knowing would become feeling Is that so different from the history of human music? 24 of 33 4

5 6. Lady Lovelace s Objection Lady Lovelace (who worked with Babbage, if you didn t know) said The Analytical Engine has no pretensions to originate anything. Which boils down to computers can t be creative, which we have just covered. 7. Continuity of the Brain The brain is a continuous state machine (so the argument goes). It does not move from discrete state to discrete state like a digital computer Intelligence might need that continuity, and computers don t have it Or, more generally, computers aren t brains and only brains can be intelligent 25 of of 33 Can Only Brains Be Intelligent? To argue that there is something in the hardware of the brain that causes intelligent behaviour requires that you identify what it does Otherwise, you are back to mathematical objection 8. Informality of Behaviour Computers need rules to follow and humans don t There can t be a rule that dictates what a person would (should?) do in every circumstance they will ever encounter there would be infinitely many rules, you d never fit them all in your head! So, you couldn t program them into a computer either Humans somehow manage to act in every possible circumstance, even though we can t have all the rules, but a computer would fail 27 of of 33 The Easy Answer Computers can generalise from the rules they do have to new situations Neural networks, for example, can respond to inputs they have never seen before with a statistically optimal output They can also change their internal state to improve that response next time 29 of 33 A Great Can of Worms Another way to state this objection is Computers are deterministic, humans aren t Or, humans have free will. You could use all the arguments we have just seen to argue about free will Dualism where does free will live? Creativity does free will give us creativity? Consciousness the seat of free will? If we are not following rules, what are we doing? Is free will the ability to choose whether or not to follow the rules? If so, how do we choose? 30 of 33 5

6 9. ESP Yes! Really. Turing was quite taken with the idea of telepathy He worried that it would allow the human to see inside the mind of the participants in the Turing test to see which was the human That would certainly help us decide whether or not computers had a mind! Summary on Turing Arguments against AI boil down to: Dualism is there some other part to our intelligence that is outside the physical brain and beyond the scope of implementation in a computer? Consciousness, for example Determinism is intelligence computable? Are emotions? Is creativity? 31 of of 33 Finally The idea that there are some parts of our mental life that are immune to the laws of computation and determinism If they exist, we may never make a truly intelligent computer If they exist, however, we know nothing of how they operate, or where they are We might need something more powerful than a brain before we can understand a brain! 33 of 33 6