Much humbug is spouted in the form of a theory, but a seeker after truth ought not to dismiss any theory a priori. However, given the large amount of excrement being continually generated by wackos, it's a good idea to have a handle on what constitutes a genuine scientific theory, and what doesn't. One can combine this with other criteria, such as Occam and Hume's razors, to determine the credence one gives to any particular theory.
The reason we give (provisional) consent to any theory is because, compared to any alternatives, it is backed by the most convincing evidence, has the greatest explanatory power and is the least convoluted. Unless some science is done to cast doubt upon it, or a new theory which offers greater explanatory power and is more parsimonious is proposed, we have no good reason and it serves no useful purpose, to doubt it. According to Ben Ari:
A scientific theory is a concise and coherent set of concepts, claims and laws (frequently expressed mathematically) that can be used to precisely and accurately explain and predict natural phenomena.Homoeopathy falls into the above category. If we use Ben-Ari's definition of a theory as the demarcation criterion (to tell the difference between a scientific theory and horse manure), we can see that homoeopathy has been studied scientifically [pdf], yet it is clearly a pseudo-science. Homoeopathy lacks experimental evidence (it doesn't precisely and accurately explain and predict natural phenomena) and it has no plausible mechanism (unless you take the word of 'homoeo-physicists': “It’s quantum memory mechanics”, or whatever they actually call it...). Consequently there is no good reason to give it any credence whatsoever. Herbal medicine, on the other hand, though it still isn't science (it is far from coherent and lacks credibility), it has the potential to be scientific (there is undoubtably a mechanism by which herbs can affect the body).
A theory should include a mechanism that explains how its concepts, claims, and laws arise from lower-level theories. (Original emphasis.)
I'll end this with a quote that I use at the beginning of my book review, by Bertrand Russell in History of Western Philosophy:
It is not what the man of science believes that distinguishes him, but how and why he believes it. His beliefs are tentative, not dogmatic; they are based on evidence, not on authority or intuition.____________________
Ps - Jef is a regular contributor to the skeptic - his latest essay is a greatly developed explanation of Bad Faith - the funniest thing I've read for a long time.
Tagged - Fallacy Skepticism, Science, Philosophy, Theory.