The dysfunctional consequences of the Cartesian dichotomy have been enhanced by the power of biomedical technology. Technical virtuosity reifies the mechanical model and widens the gap between what patients seek and doctors provide. Patients suffer "illnesses"; doctors diagnose and treat "diseases". Illnesses are experiences of discontinuities in states of being and perceived role performances. Diseases, in the scientific paradigm of modern medicine, are abnormalities in the function and/or structure of body organs and systems. Traditional healers also redefine illness as disease: because they share symbols and metaphors consonant with lay beliefs, their healing rituals are more responsive to the psychosocial context of illness. Psychiatric disorders offer an illuminating perspective on the basic medical dilemma. The paradigms for psychiatric practice include multiple and ostensibly contradictory models: organic, psychodynamic, behavioural and social. This mélange of concepts stems from the fact that the fundamental manifestations of psychosis are disordered behaviours. The psychotic patient remains a person; his self-concept and relationships with others are central to the therapeutic encounter, whatever pharmacological adjuncts are employed. The same truths hold for all patients. The social matrix determines when and how the patient seeks what kind of help, his "compliance" with the recommended regimen and, to a significant extent, the functional outcome. When physicians dismiss illness because ascertainable "disease" is absent, they fail to meet their socially assigned responsibility. It is essential to reintegrate "scientific" and "social" concepts of disease and illness as a basis for a functional system of medical research and care.