[[quoteright:320:[[WebComic/{{XKCD}} http://static.tvtropes.org/pmwiki/pub/images/naturalxkcd_986.jpg]]]]
--> ''"They used to advertise, 'If you've eaten a banana and drank some milk, you've had everything in N*Sweet.'"''
--> ''"My reply was, 'You've also had everything in potassium cyanide. So what?'"''
-->-- Joe Zeff, [[{{USENET}} ASR quotes]]

The [[http://en.wikipedia.org/wiki/Appeal_to_nature Appeal To Nature]], also called the Natural Law Fallacy, involves assuming something is good or correct on the basis that it happens in nature, is bad because it does not, or that something is good because it "comes naturally" in some way. This is fallacious because it turns "natural" into an ideal state without any meaningful reason, effectively using it as a synonym for "desirable" or "normal."

->'''Bob:''' "My father is terribly ill at the moment, but the doctors say this new treatment will save his life."
->'''Alice:''' "That treatment is unnatural. You need to accept that it's your father's time rather than trying to fight it."

:: Obviously, Bob's father is unlikely to consider himself better off dead than alive. This fallacy is sometimes combined with RetrospectiveDeterminism, arguing that a given event was "just the way things are" and hence should not be regarded as negative. "It's nature's way." See below for this variant.

This is an expression of the ''is/ought dichotomy'' which separates objective science (what is) from ethical behaviour (what ought to be). The theories of nature and sciences only provided a ''description'' of how the world works, not a ''prescription'' for how people should behave. Science only understands how, but do not understand why. On the other hand, ethics deal not with what is scientifically true, but what is ''desirable''. Hence using science to justify ethics will never work, because, pragmatically speaking, ethics cannot be tested in nature. Unlike the laws of physics, the laws of morality can be broken and science cannot prove the transgression as inherently wrong. Science only knows that murder exists, and cannot prove murder as wrong (This often comes up in WhatIsEvil). Science is AboveGoodAndEvil.

It can also can arise from a fallacy of ambiguity since the words "normal" and "natural" have two meanings: "what is", and "what should be".

On the other hand, not providing any evidence whatsoever (such as through an ontological argument or CircularReasoning) got you denounced as a liar and a charlatan. This led to widespread use of using every scientific discovery to justify a behavioral or moral standpoints.

In politico-religious discussion by MoralGuardians, the phrases "homosexuality is (not) normal/natural because [[http://en.wikipedia.org/wiki/Homosexual_behavior_in_animals no homosexual animals]]" and/or "Rape is less sinful than Masturbation because procreation is natural" epitomize this semantic and logical problem.

The entire fallacy of using nature to justify a moral standpoint can be pointed out by pointing out that NatureIsNotNice; it's rife with disease, natural disasters, parasites, predators, murder, rape (because it fulfills the natural purpose of procreation) and other ghastly things, while on the other hand, "unnatural" civilization made people behave more morally, allowed ethical philosophy to be conceived, and made the rates of mortality and suffering descend fast. Users of this argument also conveniently show that humans are, in fact, acting according to their nature (the hunger drive) and it is therefore natural, as are their most basic resources. Somewhere down the line of turning these resources into beneficial tools do these lose the label natural.

This fallacy is not limited to use by MoralGuardians, however, and non-Moral Guardian people can end up using this as well; for example, the use of natural selection to justify SocialDarwinism and [[TheSociopath sociopathy]]. Another extreme example is that we should all become hedonistic {{Straw Nihilist}}s because as aforementioned, there's no natural evidence for any kind of moral behavior except eating and fucking.

In moral philosophies, ethical non-naturalism, [[TheAntiNihilist existentialism]] and other no-need-for-proof moral codes attempt to defy this trope, but are often unpopular because as said, there's no natural evidence to follow for everybody.

This is related to ScienceIsBad. Frequently results in AllNaturalSnakeOil. May also be related to TheFarmerAndTheViper, if someone uses "it's my nature" as an excuse/justification for an evil act.


!!! Examples:
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[[folder: Advertising ]]

* Any commercial that tells you its product is all-natural or accuses its competitors of using artificial ingredients. Less directly are commercials for foods that depict rolling hills, farmers in fields with tractors, rivers winding through mountain ranges, or attractive people leisurely sitting on park benches or exploring national parks when talking about themselves; or when talking about their competitors, depict scientists in sterile white laboratories pouring brightly-colored chemicals, large industrial machines mixing and packaging the food, or people doing math on chalkboards.

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[[folder: Film ]]

* In ''Film/{{Troll 2}}'', an evil witch is able to convince [[IdiotBall someone]] to drink a steaming green broth that has just turned someone else into green goo because "it is made from vegetable extracts".

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[[folder: Literature ]]

* In the ''Literature/{{Discworld}}'' novel ''Discworld/CarpeJugulum'', King Verence is talked into drinking [[GargleBlaster brose]] after being told "It's got herbs in", on the assumption it must be healthy. He spends most of the remainder of the book foaming at the mouth and randomly attacking inanimate objects. This, however, turns out to be useful. It should be noted that brose is what the Nac mac Feegle, six-inch pictsies who can drink their weight in lamp oil with no ill effects, drink to get their spirits up before marching into battle.
** Similarly, the popular drinks Scumble (made of "mostly apples") and Splot containing such vaguely defined ingredients as "tree bark" and "naturally occuring mineral salts".
** Pratchett has a lot of fun with this trope; both Verence and his wife Magrat fall prey to it on a regular basis, usually for the worse (in Witches Abroad, teetotaller and lightweight Magrat drinks a third of a bottle of absinthe because she vaguely recognizes it as involving wormwood, after which point she, Granny Weatherwax, and Nanny Ogg start calling it "herbal wine"). In another book, Ankh-Morpork's notorious CMOT Dibbler is making himself a killing off a particularly desperate dandruff sufferer selling herbal shampoo "now with more herbs!" One character notes, "throw a bunch of weeds in the pot and you've got herbs."
** In ''Discworld/TheFifthElephant'', when [[TyrantTakesTheHelm Acting-Captain]] Colon says he's opposed to "unnatural things" like Sonky's contraceptives, Lord Vetinari replies "You mean you eat your meat raw and sleep up a tree?"
** Vetinari also takes a dig at the Appeal to Nature in ''Discworld/GoingPostal'': "Freedom may be the natural state of mankind, but so is sitting in a tree eating your dinner while it's still wriggling."

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[[folder: Live-Action TV ]]

* ''Series/TheSarahJaneAdventures'', where aliens convince millions of people to drink a new energy soda [[spoiler: that contains alien parasites]] called "[[NamesToRunAwayFromReallyFast Bane]]" simply by claiming that Bane is "organic" (and by extension "healthy").
* ''{{Series/Eureka}}'' had an episode where everyone was becoming dumber, and the supposedly-a-genius farmer didn't think the additives she were using were bad, since they were "organic"...In a town of super-geniuses, granted lacking in common sense sometimes, this seemed rather glaring in its stupidity.
* Parodied in a ''[[ABitOfFryAndLaurie Fry and Laurie]]'' sketch where a doctor is offering his patient cigarettes as a cure. "They're herbal are they?" asks the patient. "Yes, a naturally-occurring herb called tobacco, I believe."
** Another Fry and Laurie sketch had a bedtime drink containing "nature's own barbiturates and heroin".
* In CosmosASpaceTimeOdyssey, Neil deGrasse Tyson points out that an appeal to nature was used to justify using the dangerous gasoline additive tetraethyllead, or "leaded" gasoline. Part of the campaign General Motors used was simply pointing out that lead was a naturally occurring element in the environment. Likewise, paint companies would resort to similar appeals. Long before the 60's, lead's toxicity was well established to scientists, but the public outcry wasn't there. To a lay person, the appeal to nature could be convincing. A person with even a modest amount of knowledge of chemistry could say, "As are arsenic, mercury, and uranium; should I be ingesting those, too?" To this day, the cost of lead poisoning is staggering. A study available on the web at the website of the NIH of the United States puts the return on investment of eliminating lead at [[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717145/ about 1700-2100%]]. Links between lead levels and criminality (controlling for other factors, such as income, neighborhood, and race), lower IQ, poorer school performance, and increased medical expenditures are uncontroversial in modern medical science. This fallacious argument to keep using lead led to terrible consequences we're still paying for today.
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[[folder: Video Games ]]
* ''VideoGame/JadeEmpire'' is a pretty severe offender. Much of the setting's backstory revolves around a conflict between the Emperor and the Water Dragon, one of the setting's nature deities. The short version: the Water Dragon allowed (or ''caused'') a severe drought that nearly crippled the Empire and cost thousands of lives, and the Emperor captured, tortured, and maimed the Water Dragon to force her to make the drought stop. While the other characters never waste an opportunity to condemn the Emperor's actions, none of them ever do the same for the Water Dragon and automatically dismiss any suggestion that the Water Dragon's drought was anything but 100% justified, and this trope, along with OmniscientMoralityLicense, is strongly implied to be the reason. Granted, [[JustifiedTrope the setting and culture are based on Chinese mythology]], and the characters' unwillingness to question the morality of a goddess makes sense in context, but to a modern viewer, the ValuesDissonance can be pretty jarring.

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[[folder: Tropes ]]

* See AllNaturalSnakeOil for a lot of examples of this.
* This is the underlying logic of TheSocialDarwinist and often the EvilutionaryBiologist; there are various versions, typically some variant of:
** The strong deserve to rule over and / or destroy the weak, because it's nature's way.
** Mankind has perverted the course of nature, so society needs to be destroyed / someone needs to genetically engineer a killer something to prey on man / whatever.
* This might also be why people think [[CyberneticsEatYourSoul cybernetics will eat people's souls]].
* A lot of LotusEaterMachine plots tend to run into this, particularly ones in which there's nothing at stake except "freedom". Part of what makes the LotusEaterMachine so appealing is the fact that, more often than not, the "victim"'s quality of life is much higher inside the machine than outside it, but it's almost always dismissed by the characters anyway because "it's an unnatural fantasy," "it's not real," "humans weren't meant to be (that) happy," and other [[FantasticAesop transparently flawed reasons.]]

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[[folder: Real Life ]]
* This is often used with regard to social issues; for example, the more extreme opponents of feminism argue that the natural order is for males to be dominant, so women should not be allowed the same rights as men. (This argument is itself unsound, as many species, especially bugs, will attest to.)
** Not just bugs. In quite a lot of species the lowest-ranking females is well above the most powerful males -- including our closest living relative, the pygmy chimpanzee. Some species, such as the whiptail lizard, have even done away with males all together and created a RealLife OneGenderRace.
** Any politician who remembers how he was "raised at the farm" and he never saw any homosexuality there... biologists know that homosexuality is common between animals.
*** Note, however, that using the existence of homosexuality among animals, or of species where the female is larger and stronger, to denounce homophobia and sexism is actually just as much an Appeal to Nature, and therefore just as invalid if that is all you use to back up your position. Invalid arguments your opponents use do not become valid when you're using them. However, these facts are most often raised to refute an Appeal to Nature made when the person presenting the Appeal to Nature doesn't have another leg to stand on, and it is perfectly acceptable to knock out your opponent's last, wobbly support.
* The overuse and misuse of antibiotics, pesticides, and herbicides (and the resulting resistance and health and environmental effects) have led quite a few people to denouncing ''all'' use of them per the AppealToNature, right down to claiming a ConspiracyTheory that any or all of the above are part of a DepopulationBomb conspiracy. The problem is that while overuse and misuse needs to stop, to obliterate these products entirely (or allowing their continuing overuse and misuse to do just that by creating 100% resistance) ''will'' lead to TheEndOfTheWorldAsWeKnowIt. Especially in regard to antibiotics - these are the medications that turned such diseases as pneumonia, syphilis, and bubonic plague from terminal pandemic illnesses into quickly curable illnesses. In the same way, while modern pesticides and their manufacture are bad for the environment and are carcinogenic and mutagenic, they are also a vital part in the control of disease-spreading, food-ruining, or venomous insect pests, especially for people and situations where setting up more natural methods of barriers and predators would be problematic.
* The idea of the superior "NobleSavage" has popped up repeatedly for centuries. The superiority of the primitive person or beasts over civilized man has been a repeated trope. Of course the fact that NatureIsNotNice, 25% of men died from war, 20-50% of children never left childhood, and that polygamy was invented and heavy repression of women was common primarily to repopulate after those last two points is conveniently ignored.
** Polygamy was NOT invented to repress women. That argument itself is an example of the MoralisticFallacy. Research in biology has shown humans are naturally polygamous (this is why polygamy and [[YourCheatingHeart adultery]] exist), so even if those last to points didn't happen, polygamy still would.
** Lampshaded by a December 1977 ''Magazine/{{MAD}} Magazine'' article on "The History of Medicine": "In the Stone Age, very few people had childhood illnesses. The reason for this was simple: very few people had childhoods."
* A famous example from mathematics is Giovanni Saccheri's attempt to prove the [[http://en.wikipedia.org/wiki/Parallel_postulate parallel postulate]]. In his book, ''Euclid Freed of Every Flaw'', Saccheri assumed the postulate was false and tried to derive a contradiction. Instead, he derived results that got stranger and stranger (but remained logically consistent), finally concluding that they were "repugnant to the nature of straight lines". Saccheri didn't know it, but he was developing what we now call hyperbolic geometry -- a fruitful field of study that just doesn't work the same way Euclidean geometry does.
* Eric Schlosser mentions this in ''FastFoodNation'': sometimes artificial things are better for you than natural ones. The example he uses is almond flavoring; extracted naturally, it contains trace amounts of cyanide.
** That's the nature of "natural" and "artificial" ingredients, at least as defined under United States law. Often, the active chemical is identical, the difference being that the "artificial" ingredient is synthesized directly from its components as a pure substance while the "natural" ingredient is extracted from some naturally occurring source but usually includes contaminants that aren't removed in the extraction process.
* Lots of "herbal" supplements. The idea being that because they are "herbal" they can't be harmful. Belladonna, also called deadly nightshade, which is a ''poison'', is an herb (in small amounts, it can be used as a soporific, but still). This also ignores the fact that anyone can be allergic to a plant that is not usually poisonous, making it harmful to him/her.
** In an extension of this, multiple supplements are now claiming (word for word) "It's all natural, so there are no side effects." Depending on the product, this is either a case of misleading truth (it's natural AND there are no side effects), a case of BlatantLies (it's natural, and there are some side effects, but that's not because it's natural) or a case of selective omission (it's all natural, and there are no side effects... There are no PRIMARY effects either, this is basically a placebo to help you psychologically while you do the rest of the stuff we tell you. THAT'S what makes you healthy.)
* In German, the word "Chemie" (literally "chemistry", but in this case a more accurate translation would be "chemicals") is often used to refer to certain food additives and basically any other substance that the speaker considers to be "unnatural". The fallacy is that, technically, water is a chemical too, and so is everything else. So if you're condemning the use of "chemicals", you are basically against every substance known to man, the healthy ones as well as the unhealthy ones.
** Russian has a similar phrase, "Himya s physikoi" (translated literally as chemistry with physics).
* War is often said to be bad because it's a human invention, which isn't really true.
** Also not human inventions: Agriculture (ants and termites, among others), division of labor (multiple species), language (disputed- multiple species), ownership (disputed- multiple species), tool use (apes, certain birds, and others), or... well, actually, we didn't invent a lot. We mostly just do a lot of things other species do, but do it on a grander scale. What makes humans, or perhaps even just certain cultures, unique is the method in which we adapt and pass information on, forming increasingly complex societies that have greater ecological impacts.
*** We didn't even invent paper. Wasps did that. We did, however, invent ''writing'' on paper--and writing in general, to be perfectly blunt. Wasps mostly just live in their paper, which incidentally includes shitting in it. (If you've ever seen a wasp's nest, you might notice black liquid dripping from it. That's wasp poop. [[BrainBleach You're welcome]]!)
* Both sides of the LGBT issue are guilty of this, claiming either that it is unnatural, and therefore wrong, or that it is perfectly natural, and therefore acceptable. This is particularly jarring since nobody really seems to have any idea what they mean by "natural" in this context.
* This is a point in arguments against preservation of endangered species. Extinction is a natural event that occurs when a species is no longer fit to survive in its environment. Attempting to repopulate a DyingRace works against the natural order in both the target species as well as those that share a niche. Not an example of the fallacy when referring to animals that have specifically become endangered due to human activity, such as whaling.
** This is what happened with a polar bear named [[http://en.wikipedia.org/wiki/Knut_%28polar_bear%29 Knut]]: His mother rejected him after he was born, and some people suggested to let him die because that's how it works in the wild (polar bear mothers reject any cubs if she's already raising one or two, leaving them to die), nevermind the fact that polar bears are endangered and this was a big step up in learning how to keep them from dying out.
* A mode of thought that pops up with many above topics such as war and the LGBT issue is the idea that if a human practice has a parallel among some other species, then it is acceptable. Proponents of this idea tend to forget that animals also have plenty of habits that pretty much everyone would consider grotesque, bizarre, or downright reprehensible if practiced by humans, even animals as closely related to humans as chimpanzees. This is what gave rise to the rhyme: "monkeys throw their poo, should we do so too?"
* This fallacy has been popping up in pop ethical philosophy ever since evolutionary biologists were able to explain why altruism is so widespread. People introduced to this for the first time aren't told about how atrocities can be committed as a group, it only means it's possible for ethical behavior to evolve and does nothing to define what is and isn't ethical in the first place, or the ontological issue of whether God intended for humans to evolve in this manner or humans evolved in this manner by naturalistic means.
* Back in the days when they sold radioactive water to kill off germs and "[[TheLoinsSleepTonight restore your youthful vigor]]", the ads reassured potential customers that it wasn't dangerous to their health because "Radium is not a synthetic drug or medicine but an entirely natural element, present in many hot springs famous for their recuperative properties."
* The argument in favor of the tropes MyGirlIsNotASlut and ImAManICantHelpIt. The idea is that men are supposed to impregnate as many women as they can, and thus have a ''need'' to be promiscuous, while [[AllWomenArePrudes women are supposed to be the ones that are choosy]].
* Many a StrawVegetarian has used this argument to demonstrate that a meat-inclusive diet is unnatural and unhealthy for humans.
** Similarly, proponents of such diets as the Paleo Diet decry the consumption of grain as the source of all of humanity's chronic health woes (cancer, heart disease, hormonal imbalances, dementia, obesity, and even male-pattern baldness).
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!!! Looks like this fallacy but isn't

* [[http://en.wikipedia.org/wiki/Natural_law_theory Natural Law Theory]], in which the nature appealed to refers to the essence of something, not the wild and woolly outdoors.

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