Appeal to nature
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An appeal to nature is an argument that tries to infer the properties of its subject from the subject's "naturalness" (or historical "applications"). In its general forms, the appeal to nature can be summed up as "X is natural, therefore X is good" (or superior, or moral, or any other positive quality), or "X is artificial/unnatural, therefore X is bad" (or inferior, or immoral, or any other negative quality).
Appeal to nature is a fallacious argument, because the mere "naturalness" of something is unrelated to its positive or negative qualities – natural things can be bad or harmful (such as infant death and the jellyfish on the left), and unnatural things can be good (such as clothes, especially when you are in Siberia). Another problem is the distinction of what is "natural" and what is not, which can be really murky: crude oil occurs naturally, but it's not something you'd like poured on seabirds or your garden. The word "natural" itself has no exact definition and can be used in multiple ways, thus allowing equivocation.
An excellent example of how tangled the concepts of "natural" and "non-natural", "desirable" and "undesirable" can become is the heart medication digoxin. It's a natural product of the foxglove plant, which is quite poisonous as a plant. It is chemically extracted, or sometimes chemically synthesised, and dispensed in pill form because it relieves heart arrhythmias at therapeutic levels. However, at toxic levels it causes potentially fatal heart arrhythmias — and in fact is one of the plant toxins that makes foxglove so poisonous, and there is a fairly narrow window between therapeutic and toxic levels. (One notable healthcare serial killer, Charles Cullen, used it as his killing agent of choice.) So is digoxin natural or non-natural? Desirable or undesirable?
Appeals to nature are often encountered in advocacy for alternative medicine, organic food, general lifestyle woo, anti-vegetarianism, as well as in anti-industrial and anti-technological rhetoric, usually exhibiting themselves as something like:
This is obviously flawed, as in the following "reasoning": Arsenic is natural, and therefore it is better for you than the unnatural (hence bad) acetaminophen in Tylenol. Of course, very few people actually take the appeal to nature to its logical conclusion, so they instead prefer to handwave the issue of toxic plants away with some non-reason that could perhaps be satirically described as "All plants are natural. But some plants are more natural than others."
In favor of the idea that it is better to "live naturally," some note that in earlier eras, when people "lived naturally," there were fewer cases of diseases commonly associated with the modern era, such as cancer or Alzheimer's. They argue that this is because of the lack of "synthetic" disease-causing substances in those times. However, there is another, more likely, explanation. Cancer and Alzheimer's are primarily diseases of old age. During the era of "natural living," people did not have particularly long lifespans, and so they did not, in general, live long enough to develop these diseases. (Not to mention that many significant causes of cancer are perfectly natural, such as tobacco, alcohol, and (in Taiwan) birthwort.) Another common argument is that wild animals do not succumb to chronic illnesses, in contrast to humans or their domesticated pets. This is not particularly convincing either, as this quote from Quackwatch illustrates:
“”For example, [Harvey Diamond] claims that "animals in nature are magnificently healthy in comparison to the health that we humans experience" but that pets and zoo animals develop "many of the problems of humans." The fact is that most animals in nature are infested with parasites and succumb to infections and malnutrition. It is only because predators usually kill sick animals that we don't see them stumbling across the plains and through the jungles. Perhaps it has never occurred to Harvey Diamond that the average American lives much longer than any mammal in the wild. The reason pets and zoo animals develop debilitating diseases is because they live much longer than their wild "cousins."
Alternative medicine's obsession with "naturalness" can lead to some amusing incidents. One herb company chemically tested synthetic and natural raspberry ketones to determine whether it was possible to distinguish between the two. They couldn't find any difference. Rather than conclude the synthetic and natural molecules were exactly the same, they decided not to sell the product at all, because chemicals.
This is one example of the common belief that molecules come in two forms: the ones found in plants, which are "natural" and hence safe, and "synthetic" ones, which are always inferior to and more dangerous than "natural" ones. Now, such a belief assumes that there is some method by which a "natural" molecule can be turned into its synthetic counterpart (for instance, "natural" water into "synthetic" water). That is, there should be an experimentally demonstrable sequence of chemical reactions that could turn "natural" salicylic acid (for instance) into "synthetic" salicylic acid. However, despite the outrage of those who believe "natural" raspberry ketone is superior to "artificial" raspberry ketone, and who are indignant at science's transforming "natural" remedies into identical (but more toxic) "poisonous chemicals", no such procedure has been shown to exist (nor is there any reason to believe it does, as the foxglove example above illustrates), and you will certainly not find it in any chemistry textbook. In other words, many are angered by a phenomenon they can't demonstrate or even describe!
Also, because of the Law of Conservation of Mass, no new particles can be created, so everything in the Universe is part of Nature and, one might say, "natural". All atoms, photons, and quarks are part of the Universe's repository of particles. Humans cannot create new particles.
But usually, the word "natural" is used by alternative practitioners to mean "not synthetic", that is, a substance not formed from chemical reactions caused by human intervention. This would indeed include drugs. During the infancy of chemistry, substances were taken from nature, and combined to create products (in the chemical sense). These substances, the result of combining entirely natural substances, would also be considered synthetic. But the water and carbon dioxide obtained from the reaction of sodium bicarbonate and vinegar or lemon juice would also be synthetic, according to this logic. All drugs and synthesized compounds have their origins in nature. If a human happened to combine the reactants, why should that make any difference? If the water obtained from the reaction of vinegar and baking soda isn't synthetic, then what if that water were used for a further, second reaction? Would the resulting product be synthetic? At what point does a molecule cease to be "natural"?
If the substances happened to be combined by some random force, would the product would be natural? Apparently, yes. Why? Why are some substances "synthetic" and therefore inferior, simply because a sentient being combined the reactants leading to its formation? If reactants are brought together by a human as opposed to by the random forces of nature or by some animal other than homo sapiens, why should that somehow modify the nature of the particles? Do humans have some negative aura that influences substances from a distance? Why is a product formed from the combination of reactants by a human more dangerous than one formed from the combination of reactants by random forces such as wind or gravity? And why doesn't this apply to homeopathy, which claims man-made homeopathic water is better than natural water?
 Naturalistic fallacy
This type of argument is sometimes called the "naturalistic fallacy," though that name more properly applies to a broader type of argument – a description of how the world is (or how the arguer perceives the world to be) and assumes that is how it ought to be. The philosopher David Hume commented on this confusion of the way things are with the way things ought to be as the is-ought problem, followed by G. E. Moore, who coined the term. Appeal to nature can be thought of as a specific instance of the naturalistic fallacy.
 Examples and counterexamples
Appeals to nature form the bread and butter for all nature woo: my quack remedy is from all-natural goats, and therefore good for you. For example, the anti-vaccine crowd may state that humans get immunity to diseases without vaccines, and thus conclude that vaccines are unnatural and ought not be used on children. Other examples include cyanide, a deadly yet natural poison, or smallpox; while fertilisers, many modern medicines, hygiene, and semiconductor-grade silicon do not occur naturally, they have great benefit to humans individually and in societies.
In the U.S., the food industry, aided by the Food and Drug Administration's lack of regulation on the term, has also capitalized on the "all natural" craze. For instance, we have "all-natural" Sprite, which uses high-fructose corn syrup, produced by a centrifuge. However, this still begs the question as to when something becomes or ceases to be 'natural.' Using the above example, all of the materials used to make HFCS do in fact come from raw materials. Putting a line in the sand as to using a centrifuge is arbitrary at best.
Few people take this fallacy to the logical extreme, such as living like a caveman, avoiding indoors and staying outside like a dirty animal (in the pejorative sense, not the "belonging to kingdom Metazoa" sense), with no technology or human advancements of any kind. Some hard greens have advocated it, although very few of them decide to practice as they preach and close down their websites to "live with nature." Most try to weakly argue that they "use technology against itself" or some such.
Marijuana is natural. Poison hemlock is also natural, but just ask Socrates how that turned out. Oh, wait, you cannot! He was poisoned.
 See also
- List of medicinal plants, containing herbal remedies with numerous side effects
- Biological determinism - the belief that human behavior and ability is entirely dictated by genetics
- Solferino fallacy - war is natural, and therefore good
- Moralistic fallacy - the opposite of the naturalistic fallacy, where what someone thinks ought to be is asserted to be what is
- Sense About Science - Making Sense of Chemical Stories (pdf)
- Natural, at The Skeptic's Dictionary
- Appeal to Nature, The Fallacy Files
- ↑ Plants have variable amounts of chemicals, which is why conventional medicine uses pure active ingredients rather than plants; the amount of medicine varies (sometimes wildly) from plant to plant. Drugs, on the other hand, are precisely dosed. In the example of foxglove, for instance, this means that a given quantity of one individual foxglove plant may contain a beneficial amount of digoxin, while the same quantity from another individual may be toxic. With pure drugs, this uncertainty is eliminated.
- ↑ Arsenic, lead oxide, and mercury-containing "treatments" are all in use in traditional Chinese medicine, so there may well be a number of people who actually think this way.
- ↑ Canadian Cancer Statistics 2012, Public Health Agency of Canada.
- ↑ Such as Kevin Trudeau's claim that sharks do not get cancer.
- ↑ Fit For Life: Some Notes on the Book and Its Roots, James J. Kenney, Ph.D., R.D., Quackwatch.
- ↑ 6.0 6.1 Why no Raspberry Ketones at NOW Foods?, The Herbal Insider.
- ↑ The appeal to nature is often accompanied by a comparison of the side effects of some drug, and those of some herbal supplement, with the former being more numerous and serious than the latter. It is argued that this is because of some property inherent to "natural" objects that makes them safer than non-natural ones. This comparison is flawed, however, as it works only if one ignores all the poisonous plants found in nature and not sold on the supplement market. Supplements generally are safer than pharmaceuticals, but it is not necessary to resort to pseudochemistry to explain this (besides, if such a "natural-synthetic" distinction did exist, it would mean all plants, and not just the ones on the market, would be safe; one could go into a forest and safely eat any plant matter one would find). It need only be noted that in the 19th century, when no regulations were in place, all sorts of traditional, "natural" remedies were sold, including many toxic ones not available today, such as belladonna cigarettes, lead, and comfrey, among others. Now, by contrast, these sorts of products have pretty much been banned, so, in general, only the harmless (and for the most part useless) ones remain. (RationalWiki's list of medicinal plants does, though, give many examples of currently available natural remedies that have mild to serious side effects.) In a world where all medicines were "natural" and unregulated, the medical profession's arsenal of herbs and salves, just as before the 19th century, would undoubtedly include many not particularly safe ones. The difference between the poisonous medicines of today and those of yore is, of course, that the former actually work.
Another point to be made is that drugs are tested very thoroughly, by means of trials with large numbers of people, and there are pervasive reporting systems in place to detect any possible (and potentially very rare) adverse effects they may have, after they have been launched on the market, leading to the well known lengthy lists of side effects. Side effects for herbal products, as well as non-herbal supplements, on the other hand, are not as well monitored or recorded, meaning that a herbal product could indeed have serious side effects that, because of lack of regulation or research, have simply not been discovered. It is telling to note that, before the advent of evidence-based medicine, many harmful natural remedies (such as birthwort and asbestos) were used as medicines without their harms being known (anecdotal evidence being not particularly good at detecting long-term side effects).
In addition, comparing the side effect profiles of a given quantity of a herb with that of the same quantity of a drug derived from it is like comparing apples and oranges. A drug is a pure active ingredient, whereas a plant may contain hundreds of different chemicals, of which only a few may actually have medicinal effects. Given this, it would not be particularly surprising for a given quantity of a drug to be stronger (and hence have more or more severe side effects) than the same quantity of the plant it is derived from; the drug would contain more active ingredient per weight than the plant.