Jan 16 2009
Evidence on Herbal Treatments That Goes Both Ways
Do herbal remedies work? Some may. But we don’t know until we test them. And in Little Or No Evidence That Herbal Remedies Relieve Menopausal Symptoms I read about tests conducted, and the lack thereof, on a few.
The lead string of words, however, momentarily perplexed me.
There is no strong evidence either way for several herbal remedies . . .
To me, the idea that evidence can go “either way” is fundamentally mistaken. It can also perpetuate a misunderstanding of science and what we call the burden of proof.
In a very important sense, when conducting scientific research the possible results are not either 1) evidence pointing one way — in the affirmative, or 2) evidence pointing the other way — in the negative.
Research results, verses evidence, may be used to argue the negative. “Herbal remedy X doesn’t work.” But in the strict sense, the evidence itself will always be some degree of affirmative down to null.
For herbal remedies, either there is evidence a particular one works or no evidence it works. “No evidence it works” is not the same as “evidence it doesn’t work.”
Evidence doesn’t go both ways. Sure, results can lead to opposite conclusions. But evidence isn’t bi-sensational.
As for the herbal remedies in question (black cohosh, evening primrose oil, red clover) for treating menopause, I would have worded summarizing thoughts this way: There is little convincing evidence x, y & z work.
It may seem like splitting hairs, but that is what scientific minds do. Again, you cannot test if a herbal remedy doesn’t work. You can only test if it does work. With null results, you can then conclude it doesn’t. The more null results, and the more unequivocal the results, the more confidently you can conclude it doesn’t work.
On the other hand, the default position of whether a herbal remedy works should not be “probably” or even “possibly.” The default position is “don’t know.” And it stays “don’t know” until tests are performed. From there we go to degrees of certainty in our conclusion of “works” or “doesn’t.”
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Update: I forgot to come back to the “burden of proof” point. To those unfamiliar with the concept, it is a logical principle that for any claim it is up to the claimant to provide evidence for their belief. The burden is not on others to disprove it. We don’t assume something is true because no one has bothered to attempt to disprove it or succeeded at disproving. Strictly speaking, we believe something is likely to be true because affirming evidence has been provided.
