How does that fit in with woo, you ask? Let’s give an example. A Naturopathic Doctor (ND) sees a patient who has presented with a chief complaint of allergies (itchiness, runny nose, stuffy ears, etc.). The ND believes that he treats the “whole person” and wants to help his patient by prescribing a remedy with no side effects, no drug or food interactions, no addiction risks, and one that treats the mind, body, and spirit. That is, an inert substance. Naturally (see what I did there?), he recommends a homeopathic remedy: Allium Cepa, Arsenicum Album, and perhaps a little (very very little) Arum Triphyllum ought to do the trick. Isn’t that what you usually take? Lo and behold, the patient reports feeling better when the ND checks up on her a few days later. This anecdote (along with the occasional similar success in the past) is evidence to the practitioner that the homeopathic remedy has worked. The ND has conveniently dismissed or selectively forgotten about all the times where the homeopathic remedy hasn’t helped a whit, but there’s always a reason for it: the patient wasn’t compliant, maybe it was a sinus infection and not true allergies, ad infinitum.
This reinforces the notion that the homeopathic formulary works: it has in the past, therefore it will continue to work into the future. It ignores confounding factors, published high quality research papers, lack biological plausibility, and other refuting evidence, but no matter.
How does this differ from a physician who prescribes antihistamines for the same allergy? After all, the patient anecdotally feels better and there are some patients that don’t feel better. There are two major points to be made here. First is that, unlike the ND, the MD has laboratory and clinical research on her side, other factors have been taken into consideration, and there is a known biological mechanism to explain the pathogenesis of the disease process as well as how the antihistamine works. The second point is that, from a philosophic point of view, the physician actually doesn’t know if antihistamines will work on the next patient. The induction problem says that we can not know for certain whether the future will behave like the past, so for all we know, humans could wake up tomorrow with an entirely different physiology.
Of course, in the real world this is ludicrous, hence Broad’s claim that inductive reasoning is the glory of science and the scandal of philosophy. We prescribe proven medications to patients because we assume that they will respond just as patients have responded in the past, and this is known through the aforementioned clinical and laboratory research and trials, follow up and confirming studies, doctors’ experience base, and other science based modalities. If the antihistamine in the above example turns out not to work, or has unacceptable side effects, or if something better comes along, then the medical community changes their guidelines and protocols. Can the same be said for alt med? When was they last time you saw an alternative treatment pulled off the shelves, or scrapped because of lack of efficacy? You can get back to me later if you need more time.
So, the take home message is to know that inductive reasoning is not as robust as deductive reasoning when it comes to obtaining knowledge. That doesn’t mean you can’t use it to your advantage; we do so every day. But be aware of its limitations, and that when you obtain data via this process, it should always be considered provisional and subject to change.