Kazem Sadegh-Zadeh

Medical epistemology is the philosophy of medical knowledge or simply theory of medical knowledge. Sadegh-Zadeh conceived it as a task or branch of the philosophy of medicine already in 1982 deploring that "The contemporary philosophy of medicine movement is mainly concerned with medical-ethical problems while unduly neglecting medical-epistemological ones".

Sadegh-Zadeh is the founder of analytic philosophy of medicine,. He inaugurated this new direction in the philosophy of medicine, which he based, like analytic philosophy, on the application of formal logic to distinguish it from the traditional philosophy of medicine for he did not, and still does not, consider this latter, traditional style of philosophizing on medicine a scientific endeavor, but "belles lettres". His international recognition came especially through his work on the logic and methodology of clinical reasoning, including artificial intelligence and fuzzy logic application in the theory of medical decision-making, in the theory of medical knowledge and in medical ethics. He is the founding editor of two international journals, first Metamed founded in 1977 (renamed Metamedicine later. Current title: Theoretical Medicine and Bioethics, published by Springer Verlag), and second, Artificial Intelligence in Medicine founded in 1989 (published by Elsevier). His extensive work includes the following innovative theories: a comprehensive theory of medicine presented in his monumental Handbook, theory of fuzzy biopolymers, the prototype resemblance theory of disease, the palimpsest theory of mind, and the theory of technoevolution and Machina sapiens.

Medical, or clinical, praxiology is an old term introduced by Sadegh-Zadeh in 1977–1981 already to denote a wide-ranging inquiry into the foundations of clinical practice, particularly of clinical judgment and decision-making, with the aim of reducing diagnostic-therapeutic errors and of improving physician performance. In the latter article referred to, he has defined the term explicitly as "analysis of clinical practice", "inquiry into clinical practice", and "theory of clinical practice", i.e., the philosophy, methodology, and logic of medical doing and acting. Central topics include everything related to concepts and theories that are basic to clinical practice, i.e., the concepts and theories of patient, suffering, health, illness, disease, diagnosis, etiology, prognosis, therapy, and prevention. This perspective, Sadegh-Zadeh claims, creates a fertile scientific field with a host of tasks ranging from conceptual analyses (like "what is disease?", "what is a diagnosis?", "what is differential diagnosis?", etc.) to logical analyses – such as "is clinical decision-making computable or does it require human intelligence and intuition?" – to epistemology, ethics, and metaphysics of clinical decision-making and so forth. Over the past decades, Sadegh-Zadeh's clinical praxiology has developed further with increasing sophistication. One example of his theories is the prototype resemblance theory of disease presenting a fuzzy-logical explication of the vague concept of disease:

Kazem Sadegh-Zadeh (/ˈzɑːdeɪ/; Persian: کاظم صادق‌زاده; born 23 April 1942) is a German analytic philosopher of medicine of Iranian descent. He was the first ever professor of philosophy of medicine at a German university and has made significant contributions to the philosophy, methodology, and logic of medicine since 1970.

Sadegh-Zadeh was born on 23 April 1942 in Tabriz, Iran. The fourth of eight children, he grew up in Tabriz and attended school from 1947 to 1959. His father was a craftsman and manufacturer and ran a minor terrycloth weaving mill. In the wake of severe political and economic crisis in the country caused by the U.S. and British coup d'état against the democratically elected government of Iran's Prime Minister Mohammad Mosaddegh in 1953, he went bankrupt and never recovered. At eleven years of age when entering the high school shortly after his father's bankruptcy, Sadegh-Zadeh told his parents he would become a professor of medicine in the future and provoked laughter from them. Upon finishing school education at the prestigious Ferdowsi High School in Tabriz, Sadegh-Zadeh came to Germany in March 1960 to pursue his goal as a working student and studied medicine and philosophy at the universities of Münster, Berlin, and Göttingen from 1960 to 1971 with Internship and residency 1967–1971. He earned a doctorate of medicine, Dr. med., from the University of Göttingen in November 1971. But after these five years of doing practical medicine he left clinical practice to conduct theoretical research on clinical theory and reasoning, for during his work in the hospital he had got the impression that in the foundations of clinical decision-making something was going wrong to produce about 38% errors of diagnosis and treatment. In an autodidactic way he specialized in the philosophy of medicine and was assistant professor and lecturer 1972–1982 and full professor of philosophy of medicine 1982–2004 at the University of Münster located in the city of Münster in the state of North Rhine-Westphalia in northwest Germany. He is married since 1970 and has two sons.

Not only medical theories, as non-epistemic entities, do not deserve the ascription of truth or falsehood. Regarding any other piece of general medical knowledge, Sadegh-Zadeh shows that apart from the Gettier problem, it does not fulfill the classical definition of knowledge as justified true belief. According to his detailed analysis, there are no justified true beliefs in medicine. Statements, hypotheses and theories in medicine and other fields are usually viewed as knowledge only because the ascription "this is knowledge", for example, that AIDS is caused by HIV is knowledge, is a performative conducted or affirmed by a scientific or professional community as a social group. This communitarian and social epistemology that goes back to the Polish physician and epistemologist Ludwik Fleck (1896–1961), is profitably utilized and extended by Sadegh-Zadeh.

(i) Medical ontology. Sadegh-Zadeh devotes himself extensively to pure, formal, and applied ontology to use them in his logical analysis of medical-ontological issues of medical knowledge, clinical practice, nosology, psychiatry, psychosomatics, and biomedicine such as, for example, whether diseases exist or are fictitious entities invented by nosologists and physicians, and whether particular other things such as genes, psyche, and schizophrenia exist or are mere myths. To settle these enduring controversies and similar ones in medicine, he first distinguishes between ontology de re and ontology de dicto. The distinction is based on a syntactic criterion similar to Barcan formula and enables differentiation between fictional entities such as Sherlock Holmes and real ones. Second, he inaugurates an intriguing fuzzy ontology by introducing a many-place existence operator and fuzzyfying this operator to obtain a quantitative concept of existence that he calls the Heraclitean operator. The Heraclitean operator ranges over the domain of all imaginable entities, including existent, non-existent, and fictitious ones, and over all possible frames of reference, a frame of reference being a particular language and a particular logic. As a result, an entity exists, does not exist, or is fictitious only to a particular extent in the unit interval [0, 1] with respect to a particular language and a particular logic. In this way, ontological stances such as realism, anti-realism, and fictionalism regarding whether something exists or not, become obsolete. For example, schizophrenia may exist with respect to Eugen Bleuler (1857–1939) and his followers' language and logic, while Thomas Szasz and his followers may view it as a myth with respect to their language and logic. The only remedy for irreconcilable ontological controversies of this and similar type is to care about one's unkempt language and logic, and to reach an agreement about which language and conceptual system and which logic should be used in a particular scientific discourse. Anyhow, medical language and its sublanguages as ill-structured and ill-kempt workaday languages are absolutely unsuitable for serious discourses. They allow their users too much latitude in interpretation. "Change your language or logic, and you will see another world".