by David H. Ahl
Can Computers Think? [image] by David H. Am "A Bird is an instrument working according to mathematical law, which instrument it is within the capacity of man to reproduce with all its movements." Leonardo da Vinci (1452-1519) Intelligent Machines and Today's Digital Computer A common attitude toward today's computers is that such machines are strictly arithmetic devices, While it is true that machines were first built to carry out repetitive arithmetic operations, they are capable of other, nonnumeric tasks. The essence of the computer is the manipulation of symbols-it is only a historical accident that the first application involved numeric symbols. This incorrect notion of the computer as a strictly numeric device results in the inability of many to conceive of the computer as a device exhibiting intelligent behavior, since this would require that the process be reduced to a numerical one. The reaction of many people to statements about intelligent behavior by machines seems to indicate that they take such statements to imply complete functional equivalence between the machine and the human brain. Since this complete functional equivalence does not exist, such people believe they have thereby debunked intelligent machines. Their conclusion is incorrect because this equivalence was never implied. Intelligent behavior on the part of a machine no more implies complete functional equivalence between machine and brain than flying by an airplane implies complete functional equivalence between plane and bird. The concept of comparing the behavior of men and machines in an n-dimensional continuum recognizes differences as well as similarities. For example, a common argument against machine intelligence is that the brain is a living thing-the machine is not. In our continuum we simply recognize the dimension of living and note that machines and men occupy different positions on this dimension. Is lt Possible lor Computers to Think? No-it one defines thinking as an activity peculiarly and exclusively human. Any such behavior in machines therefore, would have to be called thinking-like behavior. No-if one postulates that there is something in the essence of thinking which is inscrutable, mysterious, mystical. Yes-if one admits that the question is to be answered by experiment and observation, comparing the behavior of the computer with that behavior of human beings to which the term "thinking" is generally applied.