Empirical findings and normative judgments are inextricably interwoven when talking about diseases. The determination of which states and processes can be described as pathological is subject to value judgments. Nosological theories (nosology = classification of diseases) differ, among other things, in the emphasis given to either the empirical or the normative part within the narrative about diseases. Generally, a distinction is made between naturalistic or objectivistic theories on the one hand and normativist or constructivist theories on the other. While assessments of health status according to naturalistic theories would inevitably result from the scientific description of norm deviations from measurable physical functional performance, normativist theories emphasize the historical and cultural change in the meaning of the concept of normality, which provides the basis for our common understanding of disease. The question of which structural, functional or behavioral variants should be regarded as "normal" can be answered in very different ways. The values that guide a given socio-cultural environment would play an even greater role in the follow-up question of which deviations from the norm are disadvantageous enough to be considered pathological.

Naturalistic disease concepts can be biologically substantiated under recourse to superordinate functions of the organism as a whole and are therefore particularly plausible with regard to purely physiological investigations. In contrast, normativist theories of disease are particularly plausible in psychiatry, the history of which features numerous examples of mental illnesses that can be subject to certain "fashionable diagnoses", such as hysteria in Sigmund Freud's time or, in present times, attention deficit/hyperactivity disorder or burnout syndrome.

While the naturalistic view is that the establishment of a clinical picture begins with the observation of a biological norm deviation, to which a disease value is then attributed, the normativist view is that the opposite is actually the case: Because a behavior or characteristic is considered in conflict with currently accepted social or moral norms, an underlying disease is assumed, for which biological causes are then sought in a second step. For example, obesity is regarded as a disease because gluttony and fatness are in conflict with prevailing ideals of beauty, a pronounced worship of body and health, and a widespread appreciation of moderation and restraint. It is of course possible to identify genetic and other biological risk factors for obesity, but these in themselves would never justify the new classification of a disease, let alone cause it, in the sense that malaria is caused by parasites of the genus Plasmodium. Similarly, it would be possible to indicate genetic and other predispositions to homosexuality, the treatment of which as a mental illness was still very common until the 1970s. Normativists consider the example of homosexuality to be particularly suitable for taking the evolutionary explanatory patterns advocated by some naturalists to the point of absurdity. After all, if one argues with the criterion of reproductive success, homosexuality would have to be regarded as a dramatic biological maladaptation and consequently actually as a mental illness - which nowadays seems unacceptable. In turn, normativists have difficulty explaining why only certain socially unpopular behaviors are branded as pathological, while others are criminalized or, in less problematic cases, punished with mere disapproval.