In Memoriam

Joseph Weizenbaum (1923–2008)

Joel Moses and Jeff Meldman, Massachusetts Institute of Technology

Photo courtesy of MIT News Office

oseph Weizenbaum was born in in 1923 and SLIP also differed from Lisp in how it performed gar- died there on 5 March 2008 at the age of 85. His Ger- bage collection. J In terms of impact, Joe’s major achievement in the man-Jewish family left in 1935 and came to the ’60s was the Eliza program. Eliza, which was written US. Joe made major contributions to computer science and in SLIP, accepted scripts and then a set of inputs from a human user. It translated the inputs to SLIP lists. to the applications of computers, but was best known Each script consisted of a set of rules, which trans- as a critic of AI. While working for in formed the input. There were many such scripts, but the 1950s, he helped develop one of the first banking the most famous was a script which led to a program applications using the magnetically encoded fonts on called “doctor” that generated responses resembling checks. those of a Rogerian psychiatrist. In 1964 Joe became a visiting professor and later a Joe said he wrote most of the script for the doctor professor in the Massachusetts Institute of Technolo- program during a plane ride. There were a few dozen gy’s Electrical Engineering Department. At different rules. Many of those rules looked for a keyword, such times, each of us became a graduate student under Joe’s as “mother.” Once Eliza identified the keywords or mentorship. Later, we both became his colleagues. phrases in a sentence, it transformed them, keeping the Those were exciting times at MIT in computer science. rest of the sentence, and typed out the transformed sen- Project MAC began operations in 1963. It was a major tence. If Eliza couldn’t identify a keyword or phrase, it research program that led the development of Multi- used a stock phrase, such as “Please go on.” The “doc- Access Computers, one definition of MAC. The Artifi- tor” had no other understanding of what the user was cial Intelligence Group also joined Project MAC, work- typing. ing on Machine-Aided Cognition, another definition At the time, circa 1966, few programs of any kind of MAC. Many students felt that MAC stood for Man allowed conversations with users in a natural lan- against Computer. guage. The doctor program embedded in Eliza was an The 1960s was an exciting decade intellectually for instant success in attracting people. Joe was surprised Joe. He developed the SLIP (Symmetric List Process- when he caught his secretary using his program and ing) language, a competitor of Lisp. SLIP differed from telling it confidential things about her boyfriend. Lisp in a number of ways. It had both forward and back- Each of us remembers visiting Joe on different days ward pointers—hence, the “Symmetric” in its name. at the Stanford Center for Advanced Studies in the

 1541-1672/08/$25.00 © 2008 IEEE IEEE INTELLIGENT SYSTEMS Published by the IEEE Computer Society Behavioral Sciences during the 1972–73 cation about the morality of AI research. Joe with the 1988 Norbert Wiener Award of academic year. Joe was on sabbatical, Surely, he was right that asking comput- the Computer Professionals for Social Re- writing Computer Power and Human ers to become judges in place of human sponsibility (CPSR). Wiener, who founded Reason (W.H. Freeman & Co., 1976). He judges isn’t wise and might be immoral. the field of cybernetics, was arguably the had become concerned about the earlier But the state of the art in AI, some felt, most famous MIT mathematician ever and work of the Stanford psychiatrist Ken- was likely decades from the point that was author of the 1950 book The Human neth Colby. The doctor script intention- such an idea could even be reasonably Use of Human Beings (Da Capo Press). ally imitated a Rogerian psychiatrist who contemplated. We quote a paragraph from Terry’s tribute attempts to get the patient to keep talking Yet what truly concerned Joe ran deeper to Joe: about issues, such as the patient’s relation than what computers could or couldn’t to his or her family. But this was just an do—or should or shouldn’t be permit- From the point of view of CPSR, Wiener may be the patron saint, but Weizenbaum effort to mimic a human psychiatrist’s ted to do. His fundamental concern was had much more direct influence on the fact conversation. Colby was apparently using that the prevailing inflation and uncritical that we are here tonight. During his many a variant of the doctor script to actually trumpeting of AI achievements had the years of working with students at MIT, he treat paranoid patients. dangerous potential to produce a corre- was a teacher to many of us, and his work stimulated the thinking of many others who The book dealt with a broader set of sponding trivialization and devaluation of were not fortunate enough to be in the same concerns than the one Joe had with Colby. the human mind, of human responsibil- institution. I know that my own concerns Joe was also concerned with the attitudes ity, and of human experience as a whole. with social issues and the ethics of comput- of some AI leaders. He called these peo- And he was understandably troubled by ing were strongly influenced by my contacts ple the “artificial intelligentsia.” There’s what he saw as the small number of fellow with Joe, beginning 20 years ago. All of us can trace some part of our concern back to no question that the claims made in the AI researchers who seemed to share this Joe’s vital influence. ’50s by some, such as Herb Simon, about concern. what computers would do were inflated. Terry Winograd was an MIT AI student What was difficult for many of our MIT in the early ’70s and became a computer AI colleagues to accept was Joe’s impli- science professor at Stanford. He presented We wonder to what extent Weizen- baum’s German background influenced his views. We know that Herb Simon was a logical positivist and relatively close to analytic philosophy, which is popular in English-speaking countries. Continental

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July/ AUGUST 2008 www.computer.org/intelligent