Thomas Kuhn, in his brilliant 1962 treatise on the structure of scientific revolutions, proposed that the advancement of knowledge takes place more often in periodic surges than through slow, incremental linearity. He proposed that progress can best be understood as a sequence of “paradigms;” in his view, a paradigm was a kind of general consensus on how systems should be understood and interpreted.
When a certain paradigm governs a system of thought, it is expected that commentators, scholars, laymen, and researchers will conform to that way of looking at the system. Conformity is the expectation for entry into the discussion. The paradigm provides a lens for viewing reality, but it also works to impede progress and innovation. Views and opinions that do not adhere to the paradigm are relegated to the margins; an iron portcullis is brought down before the gate of entry, and the hopeful entrant is effectively locked out of the comforting security of the paradigm’s fortress. Eventually, however, discoveries and innovations from the excluded margins begin to make inroads into the governing paradigm’s authority. Little by little, cracks and fissures in the paradigm are exposed. What once seemed permanent and secure, gradually begins to appear rickety and inadequate. Eventually, someone will deal the governing paradigm a shattering blow that brings it down entirely; and when this happens, the old paradigm is replaced by a new one.
Kuhn’s analogy has a great deal of merit, as I see it. We could, I suppose, even call it a paradigm in itself. I was reminded of it recently, during my readings of the ancient medical writers Celsus and Hippocrates. What strikes the reader is just how astute and canny these old doctors were. It is so very easy for us today to take modern science for granted. We are accustomed to the use of chemistry, microbiology, physics, and rigorous experimental trials in medicine; yet we forget that these things are relatively recent innovations. As late as the early nineteenth century, medical education in the United States was extraordinarily primitive. Most medical schools consisted of lectures, where the works of ancient and medieval practitioners were studied. Medical knowledge was expected to be acquired through practical training and “field” experience. There were almost no entrance requirements, and experimental science was unheard of. By the middle of the nineteenth century, however, Germany began the process of revolutionizing medical practice with scientific medical research. Between 1870 and 1914, thousands of American medical students and physicians sought training and experience in Germany; from this nucleus of knowledge, America would begin to set up its own research facilities, chief among them the John Hopkins School of Medicine.
And yet the replacement of an old paradigm with a new one should not provoke within us feelings of superiority. Anyone who actually takes the time to read the old medical writers, in fact, comes away with a feeling of reverential respect. These were men groping through relative darkness, feeling their way along the walls and around the furniture; they may have been able to grasp only dimly the outlines of what they touched, but they make remarkable deductions with the tools they did have. Their shortcomings were not due to a lack of intelligence, but to a lack of access to the right equipment. Consider the utter brilliance of the ancient Epicureans, in their shocking development of atomic theory, a set of ideas based only on their acute observations of the natural world. Lucretius, in his De Rerum Natura, devotes page after page to the declinatio and inclinatio of atoms, as they swerved and surged through the void. All matter, he believed, was the result of these atomic collisions and movements. Their sizes, shapes, and particular characteristics were the ultimate determinants of the physical world. Is this not, in a foundational sense, more or less the same view held by physicists today?
Another observation one makes with the ancient medical writers, especially Galen and Hippocrates, is that some theory is better than no theory at all. Galen can be insufferably long-winded, but he is always seeking to arrive at theories to explain disease. There is a sense of order, a sense of nature’s rational control of events. The theories of the ancients were reasonable and rational because they fitted the data and observations of the time. Even if they were incorrect, they were at least based on observation. We subscribe today, for example, to the germ theory of disease; but this was not always so. In fact the first formulation of the modern germ theory of disease was not published until 1840, with Jacob Henle’s treatise “On Miasmata and Contagia.” The idea of the body being invaded by hostile entities—bacteriae, viruses, microscopic parasites—was not generally accepted.
Diseases, according to the ancients, could be caused in various ways. One way was by an imbalance in the body’s natural equilibrium or “humors.” Another way that disease was seen to spread was through noxious, putrefying gases. This “miasma” theory of disease was an attempt to arrive at a theory that could explain some phenomena associated with diseases. Malaria, a disease with which the ancients were well acquainted, literally means “bad air” (malus aer). And yet this theory, although not correct, was based on some observable truths. We know today that malaria is transmitted by mosquitoes, and that these insects inhabit swamps and other fetid places where stagnant pools of water collect; so it is not unreasonable to imagine that the spread of malaria has something to do with rotting, putrefying air hovering over certain places. The ancients did not understand microbes, but they did understand filth, uncleanliness, and putrefaction. And in a way, they were right: we know now that certain horrible disease (cholera, typhus, typhoid, and plague) are transmitted by such vectors as lice, rats, and unclean water supplies. So it was not unreasonable to associate filth with disease, and to theorize that filth, rather than microbes, caused certain diseases. The paradigm fit the knowledge that was available at the time.
The medical works of Hippocrates, in fact, are brilliant examples of rational analysis. He was the greatest of the ancient medical theorists, but we know precious little about him. He has three ancient biographers, Suidas, Tzetzes, and an obscure writer named Soranus, but none of these has left us with anything more than a few bony details. Hippocrates, the son of Heraclides, was born around 460 B.C. on the island of Cos. His instructor was his own father and a man named Herodicus; we may infer that even at this early date, medical knowledge was reasonably advanced. He was apparently a friend of the atomic theorist Democritus of Abdera, and was present in Athens during the great plague that ravaged the city during the Peloponnesian War, so vividly described by Thucydides. He lived to an advanced age as well, which is always a good indicator of a competent healer.
Hippocrates’s writings are an astute mix of religious, philosophical, and rational elements. He does not ramble; all of his ideas are based on his own experience, with a sprinkling of speculation to fill in the gaps of his knowledge. In his world, there is no place for sophistry or cant. The “theory of disease” that emerges from his writings may be crudely summarized as follows: sicknesses are cause by some imbalance in the body’s natural state, and they have a predictable pattern, depending on the disease; nature will attempt to correct the sickness, and this conflict between nature and disease will climax in the victory of one over the other; the role of the physician is to assist nature’s fight against the sickness. In broad outline, this theory of disease is not unreasonable. Hippocrates did not have the advantages of modern chemistry, microbiology, and experimental laboratories. But he did have a formidable intelligence, and understood the need for deductions based on confirmable observations. We today classify diseases based on the agent that causes them; Hippocrates did not have access to viral or bacteriological knowledge, and so organizes different ailments by symptoms. He is, at heart, a scientist, seeking to expand the boundaries of his knowledge. Consider this confident passage from his Ancient Medicine (Sect. XX), which could have been written by Descartes or Bacon:
Certain physicians and philosophers assert that nobody can know medicine who ignorant what a man is; he who would tret patients properly must, they say, learn this. But the question they raise is one for philosophy; it is the province of those who, like Empedocles, have written on natural science, what man is from the beginning, how he came into being at the first, and from what elements he was originally constructed. But my own view is, first that all that philosophers or physicians have said or written on natural science no more pertains to medicine than to painting. I also hold that clear knowledge about natural science can be acquired from medicine and from no other source, and that one can attain this knowledge when medicine itself has been properly comprehended, but till then it is quite impossible. I mean to possess this information, what man is, by what causes he is made, and similar points accurately. [Trans. by W.H.S. Jones]
This is not a man of rigid dogma, but a mind seeking to use natural science to gain medically useful information. His paradigm was “correct,” it seems to us, but he lacked only the tools that we so smugly take for granted today. Time and environment are limiting factors to the progress of knowledge. But perhaps a greater appreciation of what our ancestors knew, and what they accomplished, can serve to inspire us, to elevate our imaginations, and allow us to shatter the barriers set by our own restrictive and enforced paradigms. We should all be Hippocrates.
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