Theories and laws in medicine: devils or guiding stars?

Theories get a bad rap in homeopathy. Probably because at the very beginning of homeopathy’s how-to manual (the Organon, written by Dr. Samuel Hahnemann), there is a footnote with a rant about how physicians just sit around and theorize but don’t actually do anything – meaning they sit in their fancy offices spinning beautiful tales, but no patients get better. It’s a great visceral beginning to a book that is half rants against doctors and half how-to manual (that’s a bit of an exaggeration, but there really are a lot of rants!).

In homeopathy, the assumption is that we must follow whatever Hahnemann said like sheep, and so of course, people in homeopathy seem to hate theories. Kent, a famous American homeopath, starts his book on homeopathic philosophy, called, fittingly, Lectures on Homeopathic Philosophy, with what I would consider pages of theories. He then quotes Hahnemann saying we should never theorize, but then continues on with what I would call more theories! It's as if he genuinely believed what he said to be fact, not theory.

In the homeopathic profession, a law of cure – know as the law of similars – defines the whole profession and is always called a law. However, I doubt many other medical professions agree that it’s a law. If they agreed it was a law, they probably would stop whatever they were doing and join the homeopathic profession. So who's right? If Kent can call something fact and I call the same thing a theory, how do we know who is right? And if some people call something a law and some people wouldn't, how do we know who is right?

Facts:
These are probably exactly what you think they are. Facts are verifiable. In other words, you can easily prove them true or false (I have 10 fingers – it’s easy to check that fact). In medicine, the fact that someone got better needs to be easily verified in order to be considered fact. That’s why there’s such a push for questionnaires and grading your pain from 1-10; if you can see improvement on a questionnaire or grading scale, then you have verified the fact that someone has gotten better or not. This eliminates “wishful thinking” on the doctor’s part, and on the patient’s part. There's of course issues with this (if you said you were a 3/10 on one day, and 2/10 on another, is it because you were in a bad mood one day, or because your disease is getting worse?), but I think we all get the basic idea of this.

Theories:
Theories are statements that describe how or why facts happen. For example, the theory of evolution explains how and why there is diversity on the planet. In homeopathy, Hahnemann has a theory of the vital force. He believes the vital force is that immaterial force of nature that works in your body to keep you healthy. He believes this force is what is sick during disease. This is a theory because it is not easily verifiable (try and design that study!) and he is trying to explain how and why disease states create so many different symptoms, and why nonmaterial medicines work. He’s describing why certain facts occur. In the passage of Kent’s that I referenced, Kent argued that the cause of disease had to be immaterial because the body can be unchanged from the moment before death, to the moment after death. In other words, there is no material change, therefore it has to be immaterial (I am oversimplifying a bit for brevity’s sake). He takes facts – the body looks one way before death, and the same way after death – and tries to explain why this is true. Therefore, it’s a theory. He may be completely convinced of his theory, and therefore think of it as fact, but since it’s an explanation and not something that can be measured or observed, it’s a theory.

Laws:
Laws, in contrast, do not explain why something is true, but instead predict future events. So, for gravity, the fact that an apple falls from a tree is predicted by the law of gravity. In homeopathy, the fact that a person got better after homeopathic treatment could be predicted by the law of similars.

Who gets to say something is a law has to do with the amount of evidence that shows the law is predictive. Generally sceptics of homeopathy will say the law of similars cannot be valid because either there’s not enough data to support it as a law, or that the law makes no sense. The fact that the law makes no sense actually shows that the person wants a satisfactory theory before they believe in the law. However many scientific laws do not have accompanying theories – gravity being a classic example. Therefore generally, at the heart of it, critics refute the assertion that there is enough evidence to show the law of similars to be sufficiently predictive (as a homeopath, I obviously disagree).

What did Hahnemann mean by theory?
It’s all well and good to know the proper scientific meanings of these terms, but what did Hahnemann mean?

Hahnemann at the beginning of the Organon doesn’t explicitly say not to theorize, but that theoretical medicine should be put to bed. Now here, the difference is that a medicine has been entirely formed on theories. The medical system, in other words, only is concerned with why and how people become ill. But that’s not necessarily useful information – just because someone tells you why you are ill doesn’t mean you’ll get better. Hahnemann then, looked for a law. He wanted something that would predict what would make people better. And that’s what he found: a law of cure, which we call the law of similars. In his first edition of this book he says: “All imaginable theories concerning the functions, the inner form, and composition of the living brain in health and in disease, all the countless speculations concerning the nature of inflammation… never availed, in the world's history, to furnish a …specific remedy for the phrenitis [encephalitis] caused by sunstroke” (footnote to aphorism 13).

The place of theories in medicine:
Theories then, are probably more useful in science than in medicine. In medicine, the important outcome is whether someone gets better, which would be best predicted by laws. How and why someone is sick is less important. However in science, the how and why is more important.

That is not to say that theories have no place in medicine. Many pharmaceutical interventions, supplements, etc are created after understanding how a disease occurs, and then something is manufactured that disrupts that process. Preventing disease is also improved by having theories about how and why people become ill. For example, we theorize right now that sugar makes you more likely to get diabetes type 2. That is a statement that attempts to answer the “why” of diabetes. Understanding the why and how in this case can prevent disease in the future.
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Conclusion:
Theories may be useful or interesting sometimes, but we must always remember that they are subservient to the goal of curing people. I don’t think theorizing itself is what is “bad”. Hahnemann himself had many theories, some of which have stuck and some of which haven’t (no prescribes his insanely restrictive diet anymore, for example). Hahnemann’s point is not that theorizing shouldn’t be done. He acknowledges that he theorizes in other places in his works but does them anyway. His point is that healing is what should be emphasized, not beautiful, attractive theories.

For more information on the differences between laws and theories, see:
https://blog.ed.ted.com/2016/06/07/whats-the-difference-between-a-scientific-law-and-theory-in-ted-ed-gifs/
https://www.masterclass.com/articles/theory-vs-law-basics-of-the-scientific-method#what-is-a-scientific-theory
https://www.youtube.com/watch?v=P30QlwSsUic
The official definition of both can be found at the NSTA: https://www.nsta.org/nstas-official-positions/nature-science​