There’s a number of dangers in carrying an analogy too far. One situation may be analogous to another without being identical, or they may not in fact be analogous at all. Forgetting this principle can get you into a wee bit of trouble.
To formalize it a bit, just because you think “A” resembles “B”, and “B” has property “P” does not mean that “A” also has property “P”. It may be that “A” is not quite enough like “B” to share all of its properties.
But a weak analogy can’t stop a weak but persistent mind. Dana Ullman, Hahnemann’s cognitively-impaired bulldog, has given us a fantastically weak analogy with which he tries to delegitimize all of modern medicine (to be replaced by…what? That is his second logical fallacy: if “A” is bad, that does not mean “B” is better, a sort of non sequitur in which he asserts that modern medicine is bad and therefore magic is better).
Rather than drag you through a complete fisking of the piece, I’ll lay it out for you: doctors live by a military model in which arbitrarily-defined “enemies” (diseases) are blasted indiscriminately causing grave collateral damage. He goes on to explain how dissenters are quashed by being labelled as (gasp!) “unscientific”.
Some of his brilliant flashes of insight include this:
Doctors may even be able to go the next step and surgically remove a symptom or an obstructive agent, but the assumption that removing a single symptom or pathological agent will create health is both simplistic and incorrect.
In other words, removing an inflamed appendix doesn’t create total health and is therefore irrelevant—this one’s a “Nirvana fallacy”: because medicine isn’t perfect, it is therefore wrong in its entirety.
When trying to argue, poor Dana Ullman finds that every paper bag is a Tholian web. It should come as no surprise that a strong advocate of a religion like homeopathy would have difficulty constructing a logical argument; the acceptance of logical arguments would lead to the rejection of his religion, and for Ullman, that is clearly unacceptable.
To clarify it for Dana, who will likely stop by and say “hi”, there is no “doctatorship” in health care, at least not in the way he means it. When we discover are errors is when we are at our best. Harmful and useless practices do become accepted, but eventually the science wins out, and we reject these practices. A reader recently pointed to the Vioxx controversy, and although I’m not in complete agreement as to the relative harm of Vioxx, the example is a good one. A drug with with potentially harmful effects was dishonestly marketed, the negative data buried. For a few years, we continued to prescribe it, believing the data to support its use, but eventually the weight of data overwhelmed us, and we abandoned the drug. This is a success, not a failure.
Homeopathy is an absurd, vitalist religion whose acceptance would require us to reject most of modern science. There is no finite (or infinite) number of fallacious analogies that can change this fact.