Emergent properties define the subjective nature of health and dis-ease.

Health and dis-ease by their etymological origins refer to an evaluative, not objective, state. Health is an adaptive state, constantly reestablishing itself through interactions between the many biological, social, emotional, and cognitive factors in a person's life. Such adaptive processes define health as an emergent state. Outcomes of emergent phenomena are not precisely predictable and reside in a phase space that contains all possible states ranging from perfect to poor health states, the latter reflecting dis-ease. However, we have seen a migration of meaning from the subjective, dis-ease, to the objective, disease, referring to uniquely identifiable biomedical change. Clinical reality though teaches us that many experiences of dis-ease are not associated with any objective abnormality, an insight with important implications for clinical care and health policy.