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."
 Further analysis
Appeal to nature derives its power primarily from human exceptionalism, a widespread view that humans are fundamentally different from other animals and the rest of the natural world. Human exceptionalism is an important feature of all Abrahamic religions. This belief makes it a lot easier to accept special pleading that the effects of human activity tend to be negative, while the effects of other natural processes tend to be positive. The whole argument has misanthropic undertones.
Various beliefs in good old days, and in particular the Christian idea of original sin also give credence to this fallacy by contextualizing the development of civilization as a process of decay, rather than a process of progress.
 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, along with 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.
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.
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 (it includes some surprising 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
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|Affirming the consequent||Denying the antecedent|
Appeal to nature
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