At least as important as a particular item of medical knowledge itself is to know something about the relationships of that knowledge to the experiential world it is talking about. The reason is that the patients the physician is concerned with are parts of that experiential world. So, when using any knowledge in her practice, e.g., some knowledge on infectious diseases, a morally conscientious doctor will be interested in whether, and in what way, this knowledge relates to the ‘world out (...) there’. Does the medical knowledge she employs bear any relevance to the bodies and souls of her patients? Does it enable her to understand the patient’s suffering, illness experience, and illness narrative? Will it help her find useful diagnoses and treatments? Are there in fact any indicators of such qualities of medical knowledge? Why not use astrology, Ayurveda, or exorcism instead of the theory of infectious diseases? A prerequisite for dealing with such questions is the awareness of the relationships between medical knowledge and its referent, i.e., of the semantics of medical knowledge, on the one hand; and of the pragmatic factors beyond this semantics, which influence the role medical knowledge plays in health care, on the other, e.g., social and economic processes. In the present chapter, we shall look at these issues with an eye toward understanding why some particular information is allowed to enter the medical world as knowledge, whereas other information is considered unacceptable or quackery. Is there a clear line of demarcation between medical knowledge and self-deception? To begin with, we will discuss the issues of truth and justification because, as pointed out in Section 10.1 on page 402, knowledge is traditionally defined as justified true belief . These two defining features of knowledge, truth and justifiedness, are due to the classical conception of knowledge as the representation of some ‘reality’. This ancient, representational postulate brings with it that the predominant view on the semantics of medical knowledge is realism, i.e., the view that medical knowledge is concerned with and represents ‘the real world out there’. We shall therefore need to inquire into the philosophy and medical relevance of this doctrine before we proceed to alternative views. Our discussion thus divides into the following five parts: 12.1 Justified True Belief; 12.2 Realism; 12.3 Anti-Realism; 12.4 Beyond Realism and Anti-Realism in Medicine; 12.5 Social Epistemology. (shrink)