I want to begin this post by doing something atypical for me. I want to tell you about an amazing cure-all that I that was recently introduced to: turpentine (aka paint thinner). According to the vast wealth of knowledge available on the internet, most (if not all) diseases are actually caused by parasites, fungal infections (particularly Candida), and even modern medicine itself. Don’t worry, however, because all of these can be cured by drinking turpentine (or sometimes kerosene or even gasoline). Now, you may think that sounds crazy, but have no fear, because this treatment is totally natural (turpentine is made from distilled tree resin). Also, it has been used for nearly two centuries, and several brave doctors have bucked the medical establishment and are promoting it (e.g., Jennifer Daniels). You may think that is pretty flimsy evidence, but don’t worry, I also have multiple blogs, alternative health websites, and Youtube videos explaining why this is the cheap trick doctors don’t want you to know. Best of all, I have tons of anecdotes. There are countless success stories of people who tried traditional medicines to no avail, but as soon as they started drinking turpentine, their symptoms went away and they could just tell that they were healthier. Take, for example, this person who wrote the following after taking turpentine, “My energy level is so much better, lungs feel cleaner. Can’t tell me this stuff doesn’t work.” With confidence like that, how could they be wrong? Finally, you may be wondering why there aren’t a lot of scientific studies supporting turpentine as a treatment, as well as why there are lots of health recommendations against taking it. The answer is simple: big pharma only cares about profits, so they are suppressing the truth of this amazing treatment.
As most of you have hopefully guessed, the paragraph above is facetious, and I’m not going to try to induct you into a pyramid scheme, but I wanted to open this post that way to illustrate a very important point. Namely, most of the people reading this probably spotted the flaws in my arguments for turpentine. The idea that drinking paint thinner could cure all diseases is so outlandish that you probably realized that blogs, Youtube videos, and anecdotes aren’t sufficient evidence. You probably realized that the fact that something is natural or ancient doesn’t mean it’s safe or effective (appeal to nature and appeal to antiquity fallacies). You probably realized that the fact that I found a handful of doctors that support drinking turpentine doesn’t mean that it works (appeal to authority fallacy), and you probably scoffed at the notion that safety warnings on turpentine were actually part of a conspiracy by “Big Pharma.”
Nevertheless, despite all of that, a large portion of you probably use identical reasoning to support your favorite alternative remedy. Based on what I see in the comments, most of you probably have some “cure for the common cold” or other pseudoscientific practice that you cling to dearly, and if I asked you for your evidence, you would respond with the exact same type of reasoning. Most prominently, you would give me anecdotes and cite blogs and Youtube videos.
Further, on the off chance that someone reading this believes in the magic powers of turpentine, there is still almost certainly some other alternative practice that you think is nuts, even though it is supported by the exact same evidence base. For example, I used to know someone who believed in all manner of nonsense, from crystal healing to anti-vaccine conspiracy theories, but they drew the line at homeopathy. As I tried to explain to them, however, that doesn’t make sense because homeopathy has the same evidence base as things like crystal healing. In other words, when I asked them to give me evidence of crystal healing, they replied with blogs, Youtube videos, and anecdotes, yet they rejected homeopathy even though homeopathy is also “supported” by countless blogs, Youtube videos, and anecdotes. To try to make them grasp this paradox, I once asked them, “If homeopathy doesn’t work, then why do so many people claim to feel better after taking it?” They very correctly responded that those reports could be from placebo effects, total coincidences, regression to the mean [technically a type of placebo effect], other medications, etc. In other words, when it wasn’t their pet belief, they had no problem seeing the flaws in the line of reasoning, but when it was their personal views at stake, suddenly cognitive biases clouded their vision and inhibited their ability to think logically.
The point that I’m trying to make here is that your reasoning has to be consistent. Either anecdotes can establish causation or they can’t. You don’t get to pick and choose when you think that they work. In other words, if an anecdote, or even a collection of anecdotes, is actually sufficient grounds for saying that cannabis cures cancer, acupuncture works, vaccines cause autism, etc. then it must also be sufficient grounds for the effectiveness of homeopathy, miracle mineral solution, bleach enemas, turpentine, kerosene, gasoline, crystal healing, bloodletting, leaches, sacrificing to the sun god, and every other form of woo that has ever been proposed, because they all have anecdotes. If anecdotes actually can establish causation, then you have to believe in all of them. They can’t only establish causation when you want them to. That’s not how evidence works.
To put that another way, if for any one of the thousands of alternative treatments that have ever existed, you are content to say, “the anecdotes could easily be from placebo effects or other factors,” then you must say that for all of the treatments. In other words, by acknowledging even once that the fact that someone took a treatment then got better is not good evidence that the treatment actually works, you have just universally acknowledged that anecdotes can’t establish causation. The logical syllogism, “someone took X, then got better, therefore X works” either works all the time or it never works. It can’t magically work when you want it to, then not work when you don’t want it to.
The same thing is true for the admissibility of blogs and Youtube videos as evidence. If you asked me for evidence that turpentine is a cure-all, and I responded with an unsubstantiated Youtube video, you would very correctly demand actual data. It is inherently obvious that any crackpot can make a Youtube video and say whatever they want in it. To be clear, there are some Youtube videos, blogs, etc. that are packed with non-cherry-picked citations to the original peer-reviewed literature, and there is nothing wrong with linking to a source like that and saying, “this video gives a good explanation and cites the relevant literature.” That is, however, almost never what I see when it comes to conspiracy theories and alternative medicine. The sources that I see people use as evidence are nearly always just someone spouting nonsense as if they were stating facts, and citations to original studies are either non-existent or horrible cherry-picked.
Finally, I want to contrast this type of inconsistency with a science-based view of reality. To put it simply, you can convince me (and scientists in general) of anything if you have sufficient evidence, and by evidence, I mean multiple independent studies that used large sample sizes, adequate controls, and rigorous analyses. If you can show me a consistent body of scientific evidence demonstrating that drinking turpentine is safe and effective, I’ll accept it. If you can show me a consistent body of evidence demonstrating that vaccines cause autism, I’ll accept it. If you can show me a consistent body of evidence demonstrating that crystal healing actually works, I’ll even accept that. Do you see the difference between that and cherry-picking when you do and do not want to accept anecdotes as evidence? Science has consistent criteria for what is and is not evidence, whereas there is no constancy in pseudoscience.
The take home that I want you to get from this is that you need to ensure that your reasoning is consistent. A great way to do this is by trying to think of situations where you would not accept the conclusion that results from your current line of reasoning. For example, if you are using an anecdote to claim that a particular alternative treatment works, stop and try to think of situations where you would not accept anecdotes as evidence. In other words, if you can think of a situation where you wouldn’t accept that X caused Y, even though someone took X then Y happened, then you have just demonstrated that your line of reasoning is flawed, and anecdotes are not sufficient evidence of causation.
Note: To be clear, I am not arguing that the existence of anecdotes is evidence that something doesn’t work (that would be a fallacy fallacy). In other words, when I said things like, “the logical syllogism, ‘someone took X, then got better, therefore X works’ either works all the time or it never works,” it is the syllogism itself that is the problem, not its conclusion. To put that another way, there will always be anecdotes for things that actually do work. The problem is simply using those anecdotes as evidence that it works.
Note: Inevitably when I start talking about anecdotes, pedants get all bent out of shape and argue that anecdotes do have value because they indicate that something may be worth studying. I agree, and never said anything to the contrary. That argument does not, however, in any way shape or form negate my point that anecdotes are not valid evidence of causation. So please spare me your pointless pedantry.
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