In this article I’ll try to link XVIIe and XVIIIe century enlightenment ideas to how modern medicine is organized and operates. It will be about reductionism, evidence of the senses, different views on what science and knowledge are, separation of mind and body.
In prior posts has been shown the vital importance in medicine of the saying ‘One cause, one disease’. I argued that reducing to ‘one’ all cases of a disease and assigning ‘one’ single cause to it is a peculiar form of reductionism with some circular reasoning to it. Reductionism is the idea of understanding complex phenomena and systems from their more fundamental phenomena and elements. A well known form of reductionism is Cartesian reductionism. Named after the French philosopher René Descartes. As influential thinkers Descartes is often presented in opposition to John Locke. Locke strongly believed repeated experiments and the sensorial observation thereof were the basis of science whereas Descartes doubted the trustworthiness of his senses in this respect(Herbert Dingle, Nature, 1950).
Locke’s empiricism, as the observation of experiments is called, still is a central idea in evidence based medicine where it is used to proof therapies actually do what they are supposed to do.
Nowadays the effect of a therapy is expressed as the average percentage of change of a variable in a group of individuals. The effect might be minute and only observable in a fraction of the treated individuals. This type of knowledge Locke’s empiricism was veel rechtlijniger. Indien bij herhaling van een experiment ook maar één keer het effect niet optreed dan…………. Locke’s empiricism allowed
Building science on a growing body of knowledge. Descartes has different ideas on how science relates to knowledge. He uses the analogy of a tree where the trunk contains solid knowledge from which the different sciences evolve as branches. Here Descartes seems to have stayed close to his origin of mathematician as in resolving mathematical problems one starts by stating what is known.
Nowadays science is thought of as resting on three pillars: 1)objective measurement, 2)prediction and 3)explanation. This explanation might be a tentative one.
Although criticised for it by Locke, Descartes is mostly known for his reductionism. It seems to have evolved from Descartes’ fascination for the hydraulically powered statues in the Royal Gardens in Saint-Germain-en Laye near Paris. These automata did contribute to Descartes’ essentially mechanical view of organs and body parts. “The whole equals the sum of its parts” is what Cartesian reductionism might be resumed to. It is a simplification of “the whole is more than the sum of its parts” often attributed to Aristotle. Maybe Descartes disliked Aristotle for having his maths wrong on this simple summation.
For the shaping of medicine there is two important instances of reductionistic simplifications being made.
1)Human body disassembled into organs: For the organization of medical practice the human body has been disassembled to its component parts. Each organ got its own medical speciality assigned to it. Each medical speciality is dedicated to procuring knowledge about its assigned part. According to Cartesian reductionism, the combined knowledge of all medical specialities will provide full understanding of the human body.
2)Disease disassembled into diagnoses: Without the concept of disease there would be no medical practice. As useful as it is no single definition sharply captures the concept of disease. A commonly used definition for ‘disease’ in medical practice shows a built in form of Cartesian reductionism. This is not a definition in the classical sense where the meaning of a term is stated in a few words. It is a definition in the sense of including everything that belongs while excluding everything that is not.
I’m referring to the practice of excluding disease in patients by the elimination of every possible diagnosis. An example of this would be a general practitioner referring an elderly patient on the basis of unspecific markers of disease. Let’s say weight loss, fatigue and an elevated erythrocyte sedimentation rate. In the absence of any more clues this patient most likely will be referred to internal medicine. This might result in a diagnosis. If no diagnosis can be made this patient will be consecutively referred to those medical disciplines that are most likely to make a diagnosis in this type of patient. In the end, either a diagnosis is made or one concludes there is no disease since no diagnosis can be made. In this instance disease is conceived as the sum of all possible diagnoses.
How to conceive the mind is the last enlightenment topic discussed here in relation to the shaping of medicine. Again Descartes and Locke have different points of view regarding the nature of the mind. As said earlier, for Descartes the mind is insubstantial and therefore free to move outside the body. This is view on mind-body separation is called Cartesian dualism. To me this idea of the mind seems very close to the Christian idea of the soul. Especially for Descartes believing animals had no mind. The fact that some of Descartes’ books got banned might explain why his view on the mind stayed so close to the Christian conception of the soul. On the other hand, it is unlikely animals can make the famous Cartesian abstraction: “I think, therefore I am.”
Anyway, the insubstantial mind fits well into Descartes’ reductionistic vision of human beings. All things considered, to me Cartesian dualism and reductionism applied to a human being seem the conception of a mathematician.
The human being is nothing more than the combination of a mind and a body, with the body consisting of a set of organs and body parts. Thus, although not material the mind is just an extra part and a gain, the whole equals the sum of its parts.
Locke had a different conception of the nature of the mind. For him the mind had a physical part to it. I believe Greek philosophers already did place the mind in the brain. Anyway, Locke’s partially physical mind found its place in the speciality of neuropsychiatry. That is to say, only initially. Eventually neurology and psychiatry got split up in the decades around 1950. Neurology did inherit all diseases with proven abnormalities in the brain or nerve system. Psychiatry did inherit all conditions that lacked such objective features. The split might also be perceived as psychiatry inheriting all conditions of the mind. Personally I find it difficult to believe the only motivation for the split was the enlightenment conception of mental processes being non-physical. Fear of harm by exposure to madness, also an enlightenment idea and advocated by Descartes, might have played a role. Also, separate facilities probably better suited specific management, treatment and care issues respective to neurologic patients and psychiatric patients. Maybe conceptual simplification is just a basic human trait. This wish for simplification introduces the risk of oversimplification, which might be defined as a simplification that brings us away from knowledge(Randall Firestone, Open Journal of Philosophy, 2019).
Modern medicine seems to have been formed along ideas emerging during the XVIIe and XVIIIe century enlightenment. Notably Descartes was influential. His deconstruction of the human being in body and mind, and of the body in organs and body parts did bring the simplification required. Dualism and reductionism, together with British empiricism enabled unprecedented advances in medical practice.
Sadly this medical progress only encompasses two of the three pillars of science: objective assessment and prediction. The third pillar, explanation, faded to the background along Locke’s physical part of the mind.
More and more psychiatric conditions are being linked to objective abnormalities. Also, we found out a human being is more complex than the sum of mind, organs and body parts. Moreover, it has become clear that disease is affecting one single organ but the individual as a whole. The functional demarcation of the different organs therefore is not as sharp as their physical borders in an anatomical atlas. This might mean that the functional demarcation of diseases is equally less absolute than medical practice seems to suggest. Did medical practice introduce too much enlightenment inspired trenchant simplifications into the whole of medicine for it to keep its ability to explain anything? In my opinion, as convenient clear-cut conceptions of the enlightenment may be for medical practice, they do not justify oversimplification affecting the whole of medicine.