IEEE Computational Intelligence Magazine - February 2018 - 17

He was an Exemplary Teacher
Lotfi Zadeh argued for the need of dealing with imprecise
knowledge during the times of the space race. At that time society was convinced that the success of science and engineering
was due to increasingly complete and precise knowledge. Consequently, Zadeh faced an opposition not only against his specific approach to representing imprecise knowledge, but also
against his conviction concerning the need of processing imprecise knowledge altogether.
But Zadeh knew what he was talking about. His seminal work
in system theory had disclosed the limits of precise reasoning in
complex real-world settings. He recognized the need for abstraction and for reducing complexity through approximation. Zadeh
developed Fuzzy Set Theory to compute meaningful and correct
(albeit coarse) solutions to imprecisely specified problems. He
saw that reasoning about the real world is different from reasoning about platonic ideals. He never became tired of arguing that
the human ability of dealing with approximate knowledge exhibits a strength that permits managing complex situations efficiently and effectively, rather than a deficiency.
Zadeh was convinced that eventually the need for approximate reasoning would be widely recognized. He was right:
after 20 years of research in knowledge-based systems, we
had no longer debates on the necessity of approximate reasoning; now the question was about the best approach. Zadeh
never insisted his specific approach was always the best. He
was superb in explaining in precise language with concrete
examples from many domains how approximate reasoning
could be done. By developing a solid framework and highlighting crucial issues, he leveled the arena for many different
approaches to soft computing. Fuzzy Set Theory laid firm foundations for approximate reasoning on which thousands of scientists have built.
In times of increasing specialization, Zadeh was able to bring
together researchers from many different disciplines and to
convince more scientists about the potential of approximate
reasoning than anyone else. He was an exemplary teacher. He

paper, Fuzzy Sets, introducing the
notion of fuzzy sets as a formal mechanism to represent and manipulate concepts with ambiguous boundaries. This
was a departure from classical binary
logic and set the basis for dealing with
multiple degrees of truth and performing deductions with plausible rather
than categorical rules of reasoning. This
major scientific achievement-motivated by the need to understand and apply
the processes employed in human reasoning-led immediately to the development of a rich theoretical framework

presented and compared a wide spectrum of theories and
approaches from the literature and discussed their features and
deficiencies. Due to his modesty, he did not teach formal classes on Fuzzy Set Theory, unfortunately.
Zadeh took his students seriously and courses and seminars
had a high priority in his busy schedule until the end. Frequently
he could be seen as a student himself, sitting in a classroom to
learn and discuss. As a doctoral advisor, Zadeh pointed to interesting publications and left it up to his students to design their
own dissertation projects. He guided students by constructive
criticism and suggestions. He met them at eye level as fellow
human beings. In this way, he helped them to mature and stay
ideologically independent.
Through his openness and tolerance, Zadeh significantly contributed to the pluralistic attitude on the Berkeley campus. A
manifestation of Zadeh's academic role in Berkeley were the
periodic Round Table discussions of the Bay Area Circle on Artificial Intelligence, which he moderated; they drew wide attention. Zadeh always was fair towards his critics and provided a
forum for them to present and discuss alternative views. He
took criticism very seriously and used arguments as his main
instrument for making scientific progress in discussions, seminars, and conferences.
When Zadeh met people he always was interested in their
work and their ideas. Many students, scholars, and faculty
members from all over the world benefitted from the fact that
he introduced them to one another. In this way, he helped
many people to widen their horizon and to get established in
the Berkeley community.
Although the commercial potential of Fuzzy Set Theory was
demonstrated early on, Zadeh did not get involved with business enterprises; he devoted himself as fully as one could to
academic teaching, research, university-related activities, and
society. He is the role model of a scientist and human being for
many people who had the privilege to know him.
By Christian Freksa, Universität Bremen, GERMANY

that included the notions of fuzzy numbers and fuzzy arithmetic. At the same
time, fuzzy sets became increasingly
applied in fields such as pattern recognition, and database systems. To date this
seminal paper has received 95,000+
citations, according to Google Scholar.
It was in the context of the consideration of problems associated with the
analysis of complex systems that Lotfi
introduced, in 1973, the important
notions of linguistic variable and compositional rule of inference. The latter
concept, extending the fundamental

inferential rule of classical logic, provided
the bases for the development of numerous applications, particularly in the area
of control systems. The scope, extent, and
ubiquity of fuzzy systems-evidenced by
the journals and scholarly papers devoted
to the topic and the myriad industrial
products based on fuzzy logic-evidence
the magnitude of the ideas introduced
by Lotfi and are an everlasting testimony
to their importance. To assess the impact
of these concepts, we can consider that
the scientific community grown from his
seminal work is represented by the IEEE

February 2018 | Ieee ComputatIonal IntellIgenCe magazIne

Table of Contents for the Digital Edition of IEEE Computational Intelligence Magazine - February 2018