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      1) Post Hoc Ergo Propter Hoc: This is an extremely common lapse in deductive reasoning. It translates from Latin to “after this, therefore because of this,” but clearly a temporal correlation does not equal causation.

      2) Observation Bias: Particularly relevant to research studies, this arises when people arbitrarily remember certain results. Also referred to as selection bias, an example some may relate to is when couples argue over whether the toilet seat is being put down regularly after use. Wives generally remember only the times that they find it up and argue that their husbands never put it down. Husbands, of course, only remember if they put it down and argue they never leave it up.

There are roughly 40 common fallacies in all,¹ but they demand more space in order to examine them adequately. I’ll come back to them another time, but for now we can agree that arguments employing one of the above tactics should be identified as dubious at best. Use of one does not negate an otherwise strong argument, but can be a sign that your evidence is weak. Much of the full list is common sense, yet making a fallacy-free argument can be difficult. No matter how much restraint we have, it’s easy to fall back on a logical fallacy or two. On the other hand, we can watch for them in order to guard ourselves against pseudoscientific claims simply by asking if the claimant is using fallacies.

All of this brings me back to the issue at hand; being skeptical is an offshoot of being scientific, but that does not mean that we should check our skepticism when we exit the front gates onto York Avenue. I have always been astounded by the popularity of “natural” remedies. They have the potential for benefit, but more often than not they tend to be overpriced vitamins and herbs marketed as cures. A recent class action suit against Airborne Health, Inc., the manufacturer of Airborne cold remedy, resulted in a settlement of $23.3 million to be distributed among those who purchased their product.² The company was embarrassed when it was revealed that they had misled the public by advertising a clinical study that was suspiciously carried out in the basement of a house in Florida.³

Many people are still enamoured by the product despite zero evidence for a positive effect and several egregious examples of misrepresentation by the company. A 2004 review of their claims found “there is no conclusive evidence that this product or any of its ingredients prevents colds or shortens their duration,” and the levels of vitamin C recommended (1000 mg per dose, 3 times per day) may cause kidney stones.⁴ Likewise, each dose contains 5,000 IUs of vitamin A, which is one and a half of the safe upper limit⁵ (hypervitaminosis A can lead to birth defects and other serious problems).⁶ Still, advocates for the product will tell you that it drastically shortens, or even completely cures their colds. Why the discrepancy between science and the observations of millions of Americans? Once the logical fallacies are considered, it’s easy to see where consumers have strayed. Proponents will tell you they took Airborne, and their cold went away; case closed. Post hoc ergo propter hoc—if you take a pill and your cold goes away, it does not mean that the pill led to this end. Many people claim that they used to get terrible colds all the time until they began using Airborne. This is a classical example of observation bias—they are preferentially remembering the times that it worked. There is a saying: “If left untreated, a cold will last seven days. If you take something for it, it will last a week.” No one remembers a cold that goes away on its own, but you will always remember the times they are “cured.”

We take these arguments for granted when we scrutinize a scientific study. Scientists would never take anecdotal or cherry-picked evidence as proof, nor would they assume causation without proper supporting evidence. This is especially true in cases like this one, having no prior plausibility for the product to actually work. We should apply this same skepticism when we are confronted with a bit of pseudoscience outside of our lab. It saves us from the trouble of mailing in receipts to get a refund for a product that does not work and that may in fact cause us harm.

References:

¹ http://www.nizkor.org/features/fallacies/

² http://airbornehealthsettlement.com/index.htm

³ http://abcnews.go.com/GMA/OnCall/story?id=1664514&page=1

⁴ The Medical Letter on Drugs and Therapeutics, 1199, 2005

⁵ As defined by the Codex Alimentarius department of the USDA

⁶ http://www.nlm.nih.gov/medlineplus/ency/article/000350.htm