So what's the big deal about believing in unscientific theories of illness and healing?
In The Dangers of Pseudoscience, professor of philosophy Massimo Pigliucci and postdoctoral fellow Maarten Boudry explain,
Indulging in a bit of pseudoscience in some instances may be relatively innocuous, but the problem is that doing so lowers your defenses against more dangerous delusions that are based on similar confusions and fallacies. For instance, you may expose yourself and your loved ones to harm because your pseudoscientific proclivities lead you to accept notions that have been scientifically disproved, like the increasingly (and worryingly) popular idea that vaccines cause autism.
Histories of AIDS highlight the many times and places where pseudoscience delayed progress in understanding how AIDS was transmitted and how to prevent and treat it.
What makes this issue challenging is that "there is no sharp line dividing sense from nonsense, and moreover that doctrines starting out in one camp may over time evolve into the other." But "the criterion of falsifiability...is still a useful benchmark for distinguishing science and pseudoscience, as a first approximation."
The authors conclude:
The borderlines between genuine science and pseudoscience may be fuzzy, but this should be even more of a call for careful distinctions, based on systematic facts and sound reasoning. To try a modicum of turtle blood here and a little aspirin there is not the hallmark of wisdom and even-mindedness. It is a dangerous gateway to superstition and irrationality.
When choosing treatment, Healthy Survivors distinguish science from pseudoscience.