Descartes and the Dawn of Reductionism
And so it went, for two thousand years. The course of Western medicine continued largely unchanged until the 17th century. In 1628, years after Vesalius' dissections, William Harvey traced the circulation of blood, a feat which has often been called the greatest achievement in the history of medicine (although a Muslim physician, Ibn Nafis, has been credited with essentially the same discovery four hundred years earlier in Cairo).
But the really significant sea-change that took place at the time came from the philosopher Rene Descartes. Early in the 17th century he put forth the notion of dualism: that the human mind and body are distinct entities, neither which directly affects the other. In his view of dualism, everything in the realm of the physical operates by purely mechanical properties. Descartes included the body as part of the physical realm, viewing it as a biological machine with no free will.
One of the properties of a machine or mechanism is that it can be broken down into smaller constituents, or smaller mechanisms. It can be reduced to its parts. Thus Cartesian Reductionism was born, and it would set the stage for the paradigm shift that would change the course of science, and later, medicine as well.
Dualism was useful at the time - it also separated the physical from the spiritual, which allowed scientists to study the physical universe without charges of heresy from the Church. It laid the foundation for Isaac Newton's revolutionary work in mathematics and physics and for the development of the scientific method. But the view of the body as a machine would later lead to a purely mechanical approach to medicine. It would lead to minimizing for three centuries the understanding of the effects on healing of a patient's beliefs and attitudes, their emotions and faith, and of the power of the doctor-patient relationship.
Descartes also published in 1637 his Discourse on Method, which would lay the foundation for the development of the scientific method. This was a crucial addition - the scientific method would give scientists a schematic for studying nature. It gave reductionism its tool to study the parts systematically.
While developments in the physical sciences exploded after Newton, things moved more slowly in the biological sciences. In the 1740's, James Lind conducted a controlled experiment and discovered that scurvy could be prevented by eating limes (and since then British sailors are still called "limeys"). Then in 1798 Edward Jenner published a work that would become a beacon of the new scientific method. He discovered that immunizing people with cowpox would also inoculate them from smallpox. As important as the discovery was, possibly more important was the rigor of his methodology. He made certain that his findings were repeatable and airtight before going public. For the first time, a researcher in the biological sciences had held his own feet to the fire.
The breakthroughs came faster as the 19th century dawned. In France, Xavier Bichat discovered that organs were composed of discrete material (often found in layers) that he called "tissues". Pierre Louis began to use autopsies to compare healthy to diseased tissue. In England, John Snow ingenously used mathematics to track a cholera outbreak and concluded that contaminated water had caused the disease. In doing so, he founded the field of epidemiology. And in Germany, Jacob Henle and others formulated the germ theory of disease, which would be a landmark development of the 19th century.
Something else was happening as well, that would fundamentally affect the doctor/patient relationship. Researchers (and later clinicians themselves) were now using instruments to study and diagnose patients in a widespread way. The stethoscope was invented. Doctors incorporated the use of thermometers, which had been invented two hundred years earlier, to measure patients' temperatures. Pulse and blood pressure were measured. The laryngoscope and opthalmoscope were developed. Most significantly, the microscope with an achromatic lens came into use in the 1830's and a whole new universe of possibilities exploded for researchers, allowing themEArly to study a world that had never before been seen.
This reliance on instruments created a new distance between doctor and patient. Doctors began to rely less on their observations and their senses (a central plank in Hippocratic thought), and more on instruments, numbers, and data. To the dismay of many critics at the time (and more than a few critics since), the human body became an object to be tested and prodded (Descartes!), the results analyzed by the fields of mathematics and chemistry.
Germany was the center of the medical universe during this period. Numerous laboratories were established, with the greatest scientists of the day actively probing the nature of the body, exploring its parts and their functions in a manner that exemplified the modern scientific method. The Hippocratic writers had believed that nature should be passively observed, then theories developed. The German laboratories demolished this idea - they set up controlled experiments that poked and prodded and manipulated nature to see what secrets they could find. Jacob Henle, the first to formulate modern germ theory, summed up a basic credo of the new method, "Nature answers only when she is questioned."1
The problem with all this was that, as revolutionary as the new medicine was, very little of it yet translated into new treatments or preventions of disease. The old ways were falling out of favor, and physicians increasingly were abandoning the treatments that had been accepted for thousands of years. But nothing was there to replace them. A vacuum existed. (Wholistic medicine would partially step in to fill the vacuum during the 19th century, but more on that later).
In a bit of irony, some of the first practical discoveries that saved lives lay in the area of cleanliness and public hygiene. Scientists found that contaminated water caused cholera, typhoid was passed by food and drinking water, plague was spread by flea-infested rats…the scientists were discovering the lifesaving power of cleanliness and hygiene, a fact pointed out by Hippocrates a few centuries earlier.
While Europe was bubbling with scientific discovery in the 1800's, America was almost totally uninvolved in the revolution. The United States was experiencing the same vacuum of effective treatments that existed in Europe, but to add to that, the state of research and clinical training in America was so abysmal that the president of Harvard in 1869 said "the ignorance and general incompetency of the average graduate of the American medical schools….is something horrible to contemplate". Many states had no licensing for doctors at all. Many medical schools had no admissions standards, save for a willingness to pay the fee. No American medical school let its students perform autopsies or see patients. No American medical school taught students to use microscopes. By the mid-1800's not a single university or institution in America supported any medical research whatsoever. Many American physicians were making their pilgrimages to study at the great research centers in Europe, but they came home to a giant void, where their education and skills had no outlet. American medicine was still in limbo and adrift. That was about to change.
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