The philosophy of medicine can be defined as the ontology and epistemology of medicine. In the broadest application, it is the study of the collection of ideas, methods, procedures and practices of the art and science of maintaining health and the treatment of disease. Unlike medical anthropology which divides medical systems into its social and cultural components, the philosophy of medicine takes into account the fundamental components underlying medical practice, transcendent of geographic region and history.
From a historical perspective, the goals of medicine have evolved, and the meaning of "health" and "disease" has changed. The terms cannot be viewed objectively, but must be considered based on cultural and historical values. Over the centuries, a dispute has been engaged in between schools of thought based on the characterization of disease, either as a general state or as a quantified and localized entity. The first of school of thought began with the Hippocratic school, which proposed a physiological (or ecological) etiology of disease due to the imbalance of natural forces both inside and surrounding the patient. The second school of thought proposed an ontological theory of disease, where illness is something that invades and resides within the host. Both schools of thought have been alternatively ascendant over the course of history, and are still debated in modern clinical settings, ranging from oncology to infectious diseases.
These sometimes opposing philosophies have also been greatly underscored in differences between the medical philosophy of the Eastern and Western Hemispheres. The philosophy of Western medicine tends to separate the diseased state from the healthy state. Eastern medicine takes an integrative approach, stressing that disease and health are two sides of the same coin, where health is an expression of balance and disease is an expression of imbalance. Western medicine follows the tenets of hypothetical deduction, whereas Eastern medicine uses the inductive method. There is evidence suggesting that, in some cases, both philosophies could complement each other.
In Western medicine, as early as the 16th century, beginning with Francis Bacon, the school of empirical thought began to penetrate scientific methodology and discovery. This revolution came relatively late to the practice of medicine, however. Insights that were gained from the empirical study of animal physiology and human disease could not be practically applied to a patient, without a framework that related symptom (e.g. a rash) to disease (contact dermatitis or infectious disease). This evolved over the following centuries.
One major breakthrough in the unification of the application of science and the philosophy of medicine came in the 19th century with Heinrich Koch, who discovered the causative pathogens for anthrax, tuberculosis and cholera. He is most noted, however, for the codification of a set of principles known as Koch's postulates. Within these postulates, Koch established four criteria in order to establish a causal relationship between a pathogen and a disease:
1. The pathogen must be found in abundance in the infected tissue in all cases of the disease
2. The pathogen must be separated from an infected host and grown pure in culture
3. The cultured pathogen should cause disease when introduced into a new and disease-free host
4. The pathogen must be re-isolated from the experimental host and be identical to the original causative pathogen.
The application of these rules has been revolutionary to the practice of medicine that deals with infections, with ramifications still present today. The issue of causality was an important yet controversial milestone in the establishment of the HIV agent as the cause of AIDS.
Today a large portion of the philosophy of medicine is involved with bioethics. A term coined in the early 20th century and popularized in the 1970s as the subset of philosophy dealing with ethical questions within the field of medicine and the practice of healthcare. It is closely related to medical ethics which is the system of ethical values that defines a healthcare system. Again these values vary with cultural and social norms, but in general they include the concepts of patient autonomy, medical beneficence and non-maleficence, social justice, patient dignity, and doctor-patient transparency and confidentiality.