Story of Psychology - Morton Hunt [363]
But many programs written in the 1970s and 1980s did seem to deal with real-world phenomena. This was especially true of “expert systems,” computer programs written to simulate the reasoning, and make use of the special knowledge, of experts in fields ranging from oncology to investment and from locating veins of ore to potato farming.
Typically, such programs, designed to aid problem solving, ask the person operating them questions in English, use the answers and their own stored knowledge to move through a decision-tree pattern of reasoning, close off dead ends, narrow down the search, and finally reach a conclusion to which they assign a certainty ratio (“Diagnosis: systemic lupus erythematosus, certainty .8”). By the mid-1980s, scores of such programs were in routine use in scientific laboratories, government, and industry, and before the end of the decade many hundreds were.97
Probably the oldest and best-known expert system is MYCIN, created in 1976 and improved in 1984, which can be used to detect and identify (and potentially even treat) about a hundred different kinds of bacterial infections, and announce what degree of certainty it puts on its findings. In tests against human experts, “MYCIN’s performance compared favorably with that of faculty members in the Stanford School of Medicine… [and] outperformed medical students and residents in the same school,” notes the distinguished cognitivist Robert J. Sternberg in Cognitive Psychology (2006), “[and]… had been shown to be quite effective in prescribing medication for meningitis.” internist, another expert system, diagnoses a broader range of diseases, although in doing so, it loses some precision, resulting in diagnostic powers less than that of an experienced internist.
But although these and other expert systems are intelligent in a way that banking computers, airline reservation computers, and others are not, in reality they do not know the meaning of the real-world information they deal with, not in the sense that we know. caduceus, an internal medicine consultation system, can diagnose five hundred diseases nearly as well as highly qualified clinicians, but an authoritative textbook, Building Expert Systems, long ago pointed out that it “has no understanding of the basic pathophysiological processes involved” and cannot think about medical problems outside or at the periphery of its area of expertise, even when plain common sense is all that is needed.98One medical diagnostic program failed to object when a human user asked whether amniocentesis might be useful; the patient was male and the system simply wasn’t “aware” that the question was absurd. As John Anderson has said, “The major difficulty which human experts handle well is that of understanding the context in which knowledge is to be used. A logical engine will only yield appropriate results if that context has been carefully defined.”99 But to define contexts as broadly and richly as the human mind does would require an unimaginable amount of data and programming.
The most impressive demonstrations of computer reasoning have been the chess matches in which AI programs have defeated human chess champions. In 1997 a program called Deep Blue defeated the world’s best chess player, Garry Kasparov. In large part, it did so by brute force— searching about 200 million possible moves each second (a human being does well to manage one move per second). Since then, other programs, using far less hardware and running far more slowly, but using more strategy—particularly the kinds of creative and original strategies that chess masters can make—have defeated most of their top-level human opponents. Some of the newer programs make some counterintuitive, even ridiculous-looking, moves that can prove to be highly creative.100
Among other arguments against the assertion that AI programs think, made by many psychologists and other scientists, are these:101
—AI programs of the expert system type or with broader reasoning abilities lack intuition, a crucial characteristic of human intelligence.