When millions of patients all over the world are using remedies without any molecule of active substance, there must be at least one natural mechanism that rewards nonsense. And such a mechanism exists, as B. F. Skinner has shown in an experiment with pigeons, many years ago. I suggest that this very mechanism, random reward, may explain the evolution of homeopathy.
Martin Rundkvist, at Aardvarchaeology, has developed a nice theory which explains some aspect of this evolution. In brief: There is a selective pressure on altie medicine towards a null effect (1) because if it turned out to be effective, it would be classed as evidence-based, no longer as altie, and (2) because if it turned out to be harmful, it would be classed as dangerous and would be forbidden or abandoned. While this theory does a good job in explaining how an already existing altie method is being classified as altie, it falls short in explaining how it did evolve, how it survives extinction by lack of demand and by unwillingness of users to pay good money for nonsense, and how it even managed to invade the realm of university medicine.
B. F. Skinner's random reward experiment
As a student of biology (university diploma in animal behaviour) I have been very fascinated when I've learnt of this experiment. Briefly, a Skinner box is a cage where animals such as rats and pigeons can be trained on the task of pressing a button or key which is rewarded with food when done properly. One day, Skinner had the idea of giving a pigeon food pellets on a random basis, typically about four times a minute. There was no task. Some days later, the pigeons used to behave in a very strange way: One has been turning left all the time, another one turning right, another one was scratching the floor all over again, yet another one shaking plumage. Any behaviour that a pigeon can show, just by random, has been enforced in a crazy way. This has been observed not only in pigeons used to the Skinner box but also in naive pigeons.
A simple mechanism: reinforcement
The natural foraging behaviour of pigeons is the search of small food units in a complex environment. Whenever they find a grain, they will repeat the specific behaviour unit that led to the food. That is, a pigeon has some built-in concept of cause and effect. In the Skinner box, when the pigeon gets its random food pellet, the random behaviour of the pigeon will be enforced in a way that the pigeon shows it more often, increasing the odds of being awarded again, which enforces even more, and so on until we see that crazy behaviour.
I think that this random reward model may also explain altie medicine, for instance homeopathy. The pigeon is a model of the user. The random pellet is a model of the ups and downs in wellbeing and medical symptoms of the user. And, last but not least, the nonsensical behaviour of the pigeon is a model of the user taking nonsensical remedies.
Similia principle as a first random pellet
Just like pigeons, humans are programmed in detecting patterns in a complex world. Such a pattern has been detected by Samuel Hahnemann who, using china-bark (a herbal remedy against malaria) as a healthy person, later has been suffering from symptoms similar to malaria. Based on this "similia principle", he invented a totally different kind of medicine, homeopathy. His fever - the random pellet (a bad one of course). Taking china bark in self-experiment - the random behaviour.
A modern scientist would have repeated the trial with different persons under different conditions. Hahnemann, convinced of having detected a fundamental principle, looked for more similia cases and of course found them which reinforced his theory.
The modern user of homeopathy
Time has gone by. Today, millions of users are taking plain solvent, sold as homeopathic remedies. Again, we may use the Skinner box as a model to explain their behaviour. The worsening of symptoms is analogue to the condition without food pellet. The betterment is analogue to the pellet. And we all know that the whole life is based on rhythms - by the way a fundament of many woo theories (their arguments can be turned against them). That is, on a more or less random basis, symptoms come and go, wellbeing waxes and wanes. The best example is malaria, Hahnemann's first similia paradigm, causing periodic fever attacks.
Now, feeling worse, our user will take some drops of solvent or globules of sugar containing no effective substance - the analogue of the nonsensical behaviour of the pigeon. He will continue to do so until he feels better, which is the analogue of the random pellet that inevitably will be given. Next time when feeling worse, he will not just take the remedy but he will take it "because it had helped me before" - and here we have the analogue of Skinner's reinforcement of a behaviour element.
Resistance against logic reasoning
Needless to say that you can't tell the pigeon that it will get the pellet anyway and that it should stop behaving crazily. This is beyond its perception of the world. But it is really intriguing that the same holds true for humans. Tell them that nothing is in the remedy, and that the whole theory of action is absurd, and that science has refuted it, and they will tell you: But I have taken it yesterday, and now I feel better, and don't tell me it's just placebo because I gave it to my halting horse and now I can go out for a ride.
Orac and others have commented on this post here, and here is my own follow-up.
Photo credit: flickr.com/photos/92329000@N00/356393902/