In the most recent issue of the magazine "Skeptic", Harriet Hall, also known as "SkepDoc" writes about three fallacies that you will encounter very frequently if you engage in discussion about alternative or complementary medicine. I will of course not plagiarize Hall's article, but what I am writing here is her article, filtered through my brain (I have written about related matters here and here)...
The fallacies that you will inevitably hear are the following three;
(1) It is "natural" (and hence better for you)
(2) It has been used for a long time (and if it didn't work people would have stopped using it)
(3) It works for me (or a friend or a spouse or a friend of a friend...)
So natural is good by default ehh? In this form the statement sound very categorical, and hence, put in this fomr, the claim can be falsified by a single unambiguous counter-example, and there are plenty... Curare, a compound extracted from nature (and thus a natural compound?) will paralyze you and hence is not recommended unless you need to be still during a surgery. There are many different, naturally growing mushrooms, which will kill people who try to eat it. There is also the fen-phen scandal where a product which was advertised as an alternative medicine was later shown to have severe side effects, despite the fact that the active ingredient was "natural".
Ok, sure, there are a few extreme counter-examples, but still, isn't natural products better in general? Well this is certainly debatable and I would not jump to verdict just yet, however, the evidence to date actually tells the opposite story, namely that natural is often worse than "synthetic" (or whatever you won't to call it). Plants which are sprayed with pesticides are protected from potential predators and therefore they can use all their energy to grow. Now that I think of it, it is rather similar to us humans, in peacetime we can spend our energy on building schools and being nice to children and that sort of stuff... Plants which are not sprayed are not given their protection and therefore they have to use allot of energy on chemical warfare (or the plant-equivalent thereof). Basically they produce chemicals which will make the predator (us), sick.
But don't synthetic pesticides make you sick too? In large quantities they might (just like natural pesticides). However, pesticide control is rather strict and the chemicals used are tested so that they are of minimal danger to us... I have written more about this issue here.
The second argument says that if something has been used for a long time then it is because it is good. Again there are many counterexamples. Some people persist in using astrology even though it has been falsified over and over again. Astrologers cannot do what they claim to be able to do, and add to that the fact that their quackery is based on an astronomical model that is very out-dated. Still people are still using it… If we would have strictly gone by the "old is good" rule we would still be drilling holes in people's head to relieve headaches (here you can buy your own drill kitJ), and what about all new techniques and medicines that are developed? Are we to discard them because they are new? The fact of the matter is that we cannot rely on tradition. The way to test whether a therapy is good or bad is to do a proper, scientific test where it is possible to isolate the effect of the medicine from other factors such as placebo.
The last argument (it works for me), is the one that I have most sympathy for. In my opinion we should have respect for individual differences as well as the power of people's belief to cure them or at the very least make them feel better. If someone starts taking extra vitamins to bolster their immune system and then they do not get sick for a long time then everything is great (as long as they don't overdose which could be dangerous). Similarly, when I tell people that I am studying the brain I am often told about some therapy or mental training that I have never heard about before but which has changed their life. In those cases I normally just say that I am happy for them. However, the mistake that is often made is to assume that just because you have experienced miracles everyone else will too. Even with most conventional medicines which have a proven effect that is greater than placebo, it doesn't work for everyone. The point is that what works for you might not work for other people. Most alternative therapies have not been tested (or they have been tested with no effect). The responsible policy if you ask me is that doctors advocate therapies which have a proven effect, but do not prevent people from spending their money on other therapies (as long as they are not harmful)…