Turing and AI
"...I 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. [A.M.Turing, CMI, Sect 6]"
Note-CMI means Computing Machinery and Intelligence [http://www.ghandchi.com/iranscope/Anthology/Turing/CMI.htm]
The article "Computing Machinery and Intelligence" was written by Alan Turing in 1950. This paper had greatly influenced the first endeavors for producing artificial intelligence, and most Artificial Intelligence (AI) researchers and critics view it as the starting point of AI. Turing Machine, proposed by Turing in 1936, had continually been subject to discussion among scientists and mathematicians for decades, despite the fact that it had no claim other than defining a general scheme for computability theory.
Turing's 1950 paper, on the other hand, presented a totally different view of the machine itself. It. addressed philosophers, rather than the mathematicians, and proclaimed that digital computers may be considered as intelligent machines. This approach was wholly new, both philosophically and technically, and started a debate which still continues to this day. This is where he proposed an imitation game, as a test, what is now referred to as Turing Test, to evaluate if a machine thinks.
Turing presupposed only the potentiality of the state-of-the-art digital computers of his time, to arrive at the possibility of computer intelligence, a bold and unique feature of his claim, which differentiated his speculations from the futuristic fiction of his time, opening the way for future scientific endeavors in the field of computer intelligence. The following highlights of his approach make more sense to us today, than to the world of his times, half a century ago when he introduced the Turing Test. He:
1. Emphasized that what he intends, is not based on some hopeful futuristic computer, but is based on what the real computers available at his time can do, he writes, "...We only permit digital computers to take part in our game [A.M.Turing, CMI, Sect 3]."
2. Showed a willingness to accept conjectures, in lieu of well-established facts, to start the new field of AI He writes, "The popular view that scientists proceed inexorably from well-established fact to well-established fact, never being influenced by any improved conjecture, is quite mistaken. Provided it is made clear which are proved facts and which are conjectures, no harm can result. Conjectures are of great importance since they suggest useful lines of research [Ibid., Sect 6]."
3. Introduced an evolutionary concept of computer development, and emphasized the random element in digital computers to support this possibility. He writes. "An interesting variant on the idea of a digital computer is a digital computer with a random element...Sometimes this machine is described as having a free will," and then he opens a parentheses and writes" though I would not use this phrase myself [Ibid., Sect 4]."
4. Postulated infinite capacity computers as a theoretical possibility. He writes, "There is no theoretical difficulty in the idea of a computer with an unlimited store [Ibid., Sect 4]."
5. Predicted self-programmable machines. He writes, "..It [machine] may be used in making up its own programs or to predict the effect of alternatives in its own structure...These are possibilities of the near future, rather than Utopian dreams [Ibid., Sect 6-5]."
6. Discerned the two important paths of practical A.I research- namely simulating abstract activity on one hand, and simulating sense organs and natural language on the other [Ibid., Sect 6-7].
Despite the novel ideas above and Turing's clear replies that refute the possible objections to his theme [Ibid., Sect (6-1 to 6-9)], he has not made the four main underlying philosophical assumptions of his approach explicit. These assumptions are:
1. The permissibility of separating intellectual activity from the body and still viewing it as thinking. He writes, "The new problem has the advantage of drawing a sharp line between the physical and the intellectual capacities of a man [Ibid., Sect 2]."
2. The permissibility of expressing human thought as logical formalisms. He writes, "The question and answer method seems to be suitable for introducing almost anyone of the fields of human endeavor. [Ibid., Sect 2]."
3. The permissibility of representing reality in terms of discrete data. In fact, I do not think he has made any remarks regarding this tacit assumption.
4. The permissibility of relaying thought by means of communication. He writes, "The ideal arrangement is to have a teleprinter communicating between the two rooms [Ibid., Sect 1]."
In my opinion, the above philosophical assumptions are necessary to enable us to gather any knowledge, in general, and for building intelligence, in particular. Therefore, I think they can be declared explicitly albeit I see nothing wrong with Turing having tacitly made these underlying assumptions. The burden of proof lays with the critics of AI to show if opposite or different assumptions would be more conducive to attain knowledge.
Turing's two assumptions below limited the scope of his arguments and caused a one-sided development of AI in its early years. Thus, I think present-day defense of AI should dispense with these limiting assumptions:
1. Turing equated *intelligence* with human intelligence instead of introducing a new criteria (e.g. mathematical criteria) for determining the degrees of intelligence. He thought, this way, he was proving his claims for a stronger case, not that he was limiting himself with this assumption. He writes, "The game may be criticized on the ground that the odds are weighed too heavily against the machine...May not machines carry out something which is very different from what a man does? This objection is a very strong one, but at least we can say that if, nevertheless, a machine can be constructed to play the imitation game satisfactorily, we need not be troubled by this objection [Ibid., Sect 1].." But if it cannot be so constructed, this game which by its nature equates intelligence with human intelligence would have to be modified or not used as the test of intelligence.
2. Turing equated *machine* with the mechanical model (discrete state machines), instead of introducing higher models for the ideal machine (e.g. biological model), as a theoretical possibility. He writes, "...Modifying this computer [digital computer] to have an adequate storage, suitably increasing its speed of action, and providing it with an appropriate program...[must advance us to the ideal computer] [Ibid., Sect 5]."
Finally I would like to remark that Turing's replies to the objections were thorough enough to be used even for modem critics. Only, I think, three of the objections were not completely refuted by Turing, for which I propose alternative arguments:
1. The Mathematical Objection (i.e. Objection # 3)
2. The Argument from Consciousness (i.e. Objection #4)
3. Lady Lovelace's Objections (i.e. Objection #6)
The first one is the problem of self-reference. On page 20, Turing gives an example of solving an equation by computers as evidence for computers' capability to overcome this disability. I do not know if in light of Godel's theorem, to what extent this optimism is right. Nevertheless, I think human intellect has the same problem (considering self-reference in a wider sense of the word). Perhaps, this is also why we cannot claim to have a final answer to the question of the function of our mind as a whole. Therefore, maybe this disability is shared between humans and machines.
The second one is also similar to the first one. I think human beings have not yet found a way to completely communicate their feelings, emotions, etc. by means of language, writing and even body language. Some artists with extraordinary abilities can articulate some of their feelings much more than ordinary people. Nevertheless, we cannot even claim that they can communicate all their feelings, all the time. Thus, instead of proving that machines are able to do it completely, we should ask if humans can do this completely. Therefore, this too does not refute machine :intelligence and the limitations are shared between humans and machines.
The third objection concerns creativity. I do not think that composing sentences is creative work as critics like Dreyfus would like us to believe. Ordinary people use structures and vocabulary that are learned and there is not much creativity on their part. True, writing a poem does :involve creativity, but what percentage of human beings can perform it. In all fields of human endeavor, creative works are introduced by a very low percentage of people. This does not make others idiots, it only makes the creative people more intelligent and some of them geniuses. If we look at these as exceptions, then there is no logical difficulty having exceptions among machines to be creative, and even to have geniuses among them. We do not need to prove all machines creative to prove them intelligent.
I hope the optimism of A.M. Turing continues among AI researchers. This field is surely a great step in the evolution of man. In some sense, as I have discussed in "Intelligent Tools: The Cornerstone of a New Civilization", AI may have greater impact on human history than the sum of all socio-technological changes of the past, and I see it today closely tied with the field of nanotechnology, just as the leading AI scientist of our times, Ray Kurzweil has emphasized in the recent years.
Sam Ghandchi, Editor/Publisher
March 16, 2006
Secularism & Pluralism-Essays