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perhaps a very small variation might be the reason why a medical doctor diagnoses
a patient with disease
x
instead of disease
y
.
Therefore Fleck stated that physicians use a specific style of thinking when they
deliberate on attendant symptoms and the diseases patients suffer from. Of course,
he could not have known anything about Fuzzy Sets and Systems, but he was a
philosopher of vagueness in medical science. He contemplated a “space of phe-
nomena of disease” and realized that there are no boundaries either in a continuum
of phenomena of diseases or between what is diseased and what is healthy.
However, Sadegh-Zadeh arrived at another conclusion when I confronted him in
an interview with Fleck's view: “From the inability of physicians to make explicit
the tacit methods of their clinical decision-making, we should rather conclude the
following imperative: Stop diagnostic-therapeutic decision-making without using
any explicit logic and methodology because by conducting clinical judgment in-
tuitively - i.e., without any explicit logical and methodological foundations - you
produce too many errors of diagnosis and treatment!
Ludwik Fleck's works demonstrate that like other physicians, he didn't possess
specific knowledge of logic. Therefore, his skepticism against logic and its applica-
tion in clinical decision-making is unjustified. Obviously he has had the colloquial
idea of 'logic' in mind. But such an idea is not a very useful one in science. I
strongly believe that if Fleck had a deep understanding of logic, and more impor-
tantly, if he had been in the position to get to know fuzzy logic and its secrets, he
would have judged otherwise.” [72]
3.4.1
From Fuzzy Control to Fuzzy Medicine
“Medicine has been among the privileged areas to early recognize this revolution
and to embrace the fuzzy theory in parallel with the seminal Mamdani and Assil-
ian application in the engineering sciences and technology” wrote Sadegh-Zadeh at
the beginning of his article “The Fuzzy Revolution: Goodbye to the Aristotelian
Weltanschauung” [69]. In fact it was Zadeh's 1973-paper “Outline of a New Ap-
proach to the Analysis of Complex Systems and Decision Processes” [110] that
Ebrahim H. Mamdani (1942-2010) read by shortly after he became professor of
electrical engineering of the University of London. He then suggested to his doc-
toral student Sedrak Assilian that he devise a fuzzy algorithm to control a small
model steam engine, as he mentioned in the article that he published together with
Assilian:
“The true antecedent of the work described here is an outstanding paper by
Zadeh (1973) which lays the foundations of what we have termed linguistic
synthesis [...] and which had also been described by Zadeh as Approximate
Reasoning (AR). In the 1973 paper Zadeh shows how vague logical state-
ments can be used to derive inferences (also vague) from vague data. The
paper suggests that this method is useful in the treatment of complex hu-
manistic systems. However, it was realized that this method could equally
be applied to 'hard' systems such as industrial plant controllers.” [46, p. 325].
