which diagnostic-therapeutic rules of action primarily consist. And since clinical research pursues such rules of action and tries to improve the available ones, it constitutes explorative and normative ethics based on empirical research and experience. A central role in Sadegh-Zadeh's medical epistemology play medical theories. He analyzes the concept of "medical theory" in line with the so-called structuralist view of theories to represent their structure and content, according to Patrick Suppes and Joseph D. Sneed's approach, as set-theoretic predicates. This enables him to show that a theory in medicine cannot be confirmed, supported, disconfirmed, verified or falsified simply because it is merely a conceptual structure and no epistemic entity to be true, probable or false. It does not make any empirical claims about the world. Such claims are made using the theory as a tool. The claims themselves, as empirical hypotheses, are something different than the theory. 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. Medical deontics Apart from the deontic nature of medical-practical knowledge referred to above, a second reason why Sadegh-Zadeh classifies medicine as a deontic field is his view that according to his prototype resemblance theory of disease, the concept of disease is inherently value-laden. This is so because prototype diseases upon which nosology is based are, as phenomena, disvalued by human beings and are therefore considered to be something "that ought not to be". That means that they are, and consequently all other diseases as their resemblants are, deontic entities. The deonticity of medicine and of disease as its basic concept necessitates, according to Sadegh-Zadeh, a specific inquiry by means of suitable tools and methods, i.e., deontic logic. This research field he terms medical deontics.