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Two Rival Medical Models of Disease

Human society is based on ideas; they inform and shape all of our actions.

One hundred years ago, at the turn of the twentieth century, the great Dr. William Osler was Regius Professor of Medicine at Oxford University. He was a preeminent teacher who emphasized bedside clinical teaching; he viewed disease as a puzzle to be solved by the use of the clinician’s five senses, his knowledge of pathology and his deductive powers. The diagnosis was to reflect the pathological process that accounted for the signs and symptoms. In Osler’s mind the clinical questions were simple: "What disease does the patient have?" And, "How do I treat it?" Actually, the patient was somewhat incidental, basically a representative of the class of people with this disease. Biological individuality was disregarded. Osler was an activist; he saw the patient as a broken machine that needed to be fixed, and his role was to show the world how to fix illness.

Osler was succeeded as Professor of Medicine by Archibald Garrod; there could hardly have been a starker contrast. Osler taught how to treat disease; Garrod taught how to think about diseases and why they exist. For Garrod, individuality was a crucial element in any diagnosis and treatment. He was interested in questions such as "Why did this person get this disease, and why at this time?" And, "What can I do to restore this person’s orientation to his environment?" Garrod studied the chemical individuality of people, including inborn errors of metabolism. He saw this variability as crucially important, for from variability spring the raw materials for natural selection. Garrod was a contemplative man who saw the patient not as a broken machine, but as a consequence of the encounter of a unique individual with an environment for which he was not perfectly suited.

Two models of medicine. The prevailing metaphor of Western medicine continues to view the body as a machine which the doctor is called on to fix when it breaks. (See allopathic medicine). Medicine as engineering: doctors using technology to practical ends. The gold standard for success is cure; improvement is good, but only as a step on the road to cure. Science hunts for cures for diseases not yet understood. Lewis Thomas wrote "Disease comes as a result of biological mistakes" and "I cannot imagine any category of human disease that we are precluded from thinking our way around." The goals of medicine are to apply the theoretical knowledge of the basic medical sciences to relieve pain, to prevent disability and to postpone death. In today’s terms, by knowing the sequence of the base pairs of the genome we shall advance toward our goal of achieving a complete understanding of the biology of disease.

Fast forward to the end of the twentieth century, when cracks had appeared in the engineering approach to medicine. Not only are high-tech diagnostic and curative efforts increasingly costly, but specialization takes us ever further from the ideal of preventing disease in the first place. Because of the impossibility of learning all the facts, medical specialties break down into finer and finer sub-disciplines that focus on ever narrower pieces of the patient. In such a context, how do we maintain an awareness of the identity and human qualities of the patient? The mechanical metaphor fails to answer questions such as:

Of course, the engineer views such questions as metaphysical and irrelevant, but if we do not contemplate them we are destined to limit ourselves to developing ever more complex technical approaches to fixing problems that likely could be anticipated before they arise. Perhaps we need a new outlook that asks why diseases occur at all, what forms they take, and how we may re-orient our approach to an anticipatory, rather than a reactive, one.

Our science directs our attention ever more finely onto how things go wrong: from patient to organ, to cell, to molecule. We do not look the other way, to examine how things go right, from the individual to their family, to the environment and to evolution itself. Evolution proceeds by descent with modifications over time; the fate of individuals depends on their adaptation to the environments they meet. This returns us to variation between individuals, for if the species is to survive through changing environments there must be a stock of diversity from which to choose. In this view, individual variation represents a crucial resource for future evolution of an imperfect organism and not, as the engineering model suggests, errors from the perfect blueprint. There is, indeed, a conflict between a theological view of Man as a perfect creation, and a Darwinian view of man as a work-in-progress. Sometimes, this diversity brings the individual into conflict with their environment, and disease results. Hence, disease can be viewed as a mis-match between the person and their environment, not as a broken machine. Disease may be as much a symptom of a bad environment as of a broken person; management may entail adapting the environment as logically as fixing the individual (give people better houses!).

The doctor’s role is to conserve the individual and restoration of balance; this approach is far more tolerant of prevention than is the engineering conception. This contrast between the engineering and the natural history or adaptational views reflect contrasting approaches to science: