[[quoteright:320:[[WebComic/{{XKCD}} http://static.tvtropes.org/pmwiki/pub/images/naturalxkcd_986.jpg]]]]

-> ''The point is that just because something is natural doesn't mean it's safe. Lions are all-natural. So is hemlock. Next time you see "all natural" on the label, keep in mind that what's really unnatural is living past 30.''
-->-- Website/{{Cracked}}, in [[http://www.cracked.com/article_24352_5-natural-trends-that-could-naturally-kill-you.html this]] article.

The [[http://en.wikipedia.org/wiki/Appeal_to_nature Appeal To Nature]], also [[https://en.wikipedia.org/wiki/Naturalistic_fallacy erroneously]] called the Naturalistic 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 assumes the "natural" to be an ideal state without argument, effectively using it as a synonym for "desirable" or "normal." This is a form of [[FourTermsFallacy equivocation fallacy]], because "natural" can mean "consonant to a thing's nature, proper, fitting"; things that happen on their own do not have to fit that definition.

->'''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.

In most circumstances, Bob's father is obviously 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 gap'' which separates objective facts (what is) from ethical behavior (what ought to be). The theories of nature and sciences only provide a ''description'' of how the world works, not a ''prescription'' for how people should behave. On the other hand, ethics deals not with what is scientifically true, but what outcome is ''good'' and ''desirable''. Hence using science to justify ethics is impossible because, pragmatically speaking, ethics cannot be tested in nature.

Unlike the laws of physics, the laws of morality can be disobeyed, such that science cannot prove the transgression to be inherently wrong. Science only knows that murder exists, and cannot prove murder is wrong (this often comes up in questions of WhatIsEvil). Science cannot answer questions of good and evil, these being [[AboveGoodAndEvil out of its jurisdiction]]. All science can do is ''inform'' ethical decisions by telling people how various aspects of nature work, such as whether smoking tobacco is harmful and thus it may be immoral to advertise to people one shouldn't be harming (there is a minority of philosophers that disagree, saying science can determine moral values).

It can also can arise from a fallacy of ambiguity since the words "normal" and "natural" can both refer either to "what ''is'' commonly done" or "what ''should'' be done" in given situations.

Still, when making a moral argument for or against a given practice, not providing any evidence whatsoever that this will have a desirable or undesirable effect (making an ontological argument or engaging in CircularReasoning) typically gets one denounced as a liar and a charlatan. This leads to widespread use of the latest scientific discoveries to justify various behavioral or moral standpoints.

In politico-religious discussion by MoralGuardians, the contention often comes up that "Homosexuality is im/moral because it does/does not occur in nature." Unless (as some animists and pantheists believe) nature is a sentient entity capable of making its own decisions, these arguments are inherently meaningless and futile. (And many of these arguments are completely wrong (for instance, homosexuality ''does'' occur in nature).)

The entire fallacy of using nature to justify a moral standpoint can be clarified by pointing out that NatureIsNotNice; it's rife with disease, natural disasters, parasites, predators, murder, rape (arguably, depending on how one views certain animals' mating practices[[note]]if biologists are referring to "forced copulation", they're usually speaking about rape[[/note]]), and other ghastly things, while on the other hand, "unnatural" civilization gives people the means to behave more morally, to conceive and develop ethical philosophy, and lower the historically horrendous rates of human mortality and suffering dramatically. Those who take this position also have the convenience of questioning at what point in pursuing their natural desires (such as the hunger and procreation drives) humans' activity stops being natural and starts being artificial; this is not an easy distinction to make, as all resources and technology, no matter how sophisticated and derived from human planning and decisions, is still bound to operate according to the laws of nature.

Furthermore, criteria for determining what's "natural" and what's "artificial" vary widely: some might say that which is created or done by humans is not natural, and everything else is. Yet beavers create dams--are they unnatural? What magical ability do humans have which somehow corrupts everything they construct from nature's resources? Whatever distinctions one draws, humans are still necessarily part of nature, possessing animal needs and desires just like beavers. Therefore everything humanity creates is by definition also a part of nature. Apart from some kind of supernatural intervention (e.g. food being created by miracles), ''nothing'' that exists can unreservedly be said to be unnatural!

MoralGuardians are not the only ones to employ this fallacy; for example, some despotic ideologues have made arguments from natural selection to justify SocialDarwinism and the [[TheSociopath sociopathic]] extermination of those they deem "unfit" or "unworthy" of life. Another extreme example is {{Straw Nihilist}}s who contend for unbridled hedonism on the grounds that we are nothing ''but'' animals pursuing our animal desires for food, shelter, and procreation and should therefore stop "denying" ourselves these "healthy" natural pursuits.

In matters of ethical philosophy, ethical non-naturalism, [[TheAntiNihilist existentialism]], and other presuppositional moral codes attempt to defy this trope, but are often unpopular because as noted, the abstract presuppositions on which they rest cannot find any support in concrete scientific observations.

This fallacy is related to the notion that ScienceIsBad, and frequently underlies the advertising pitches for AllNaturalSnakeOil. An AlienNonInterferenceClause is partially an attempt to enforce this belief on ourselves in the event of contact with other as-yet unknown (usually extraterrestrial) sentient species on the grounds that interfering with their civilization's "natural" development would be wrong. This may also be related to TheFarmerAndTheViper, if someone asserts "it's in my nature" as an excuse/justification for an evil act. A specific and more contemporary outgrowth of it is the belief that NewMediaAreEvil.

The [[http://en.wikipedia.org/wiki/Natural_law_theory Natural Law Theory]] may look like this fallacy, but isn't. The nature it appeals to is the essence of something, not the wild and woolly outdoors (though its critics argue that it can't help but devolve into this still, e.g. what if something's nature isn't good?).



* 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.
* Many products are advertised as having "all-natural sugar" (or, equivalently, "no added sugar"), as if the human metabolism can somehow distinguish sugars by source.
** Among the products which advertise themselves as 'all-natural' and 'no added sugar' is ''sugar cane juice''.

[[folder:Films -- Live-Action]]
* 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".
* In ''Film/JurassicPark'', Malcolm states that bringing back dinosaurs is bad partly because that's going against natural selection. [[note]]While he may have had a point if he meant to refer to the ethics of suddenly introducing genetically altered megafauna to a region with existing wildlife, his actual point is just that "they had their chance"[[/note]]
* Detective Somerset in ''Film/Se7en'' wears JadeColoredGlasses due to decades of seeing the worst humanity has to offer, and is vocal in his pessimism. At one point in the second half of the movie, he and Mills are sitting in a bar discussing the human condition. Mills accuses Somerset of wanting to think that people should give up on civilization and go live in a log cabin, as an excuse for why he's retiring.

* ''Literature/{{Discworld}}'':
** In the 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 occurring 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 of a particularly desperate dandruff sufferer by 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."
* In ''The Big Honey Hunt'' (the first of ''Literature/TheBerenstainBears'' series), the Bear family is out of honey. Mama Bear asks Papa Bear to buy some more, but he insists on gathering it the old fashioned way, bringing along his son to search for honey from a wild comb. In the process they anger many animals, including the beehive defending the honey they want. At the end, Papa and son settle for buying honey from the store.
* ''Literature/OneNationUnderJupiter'': Diagoras invokes this, claiming homosexuality goes against evolution.

[[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}}'' has an episode where everyone is becoming dumber, and the supposedly-a-genius farmer doesn't think the additives she's using are bad, because they are "organic"...In a town of super-geniuses, granted lacking in common sense sometimes, this seemed rather glaring in its stupidity.
* ''Series/ABitOfFryAndLaurie'':
** Parodied in a sketch where a doctor is offering his patient cigarettes as a cure. "Oh, herbal cigarettes?" says the patient. "That's right, yes. The leaf originally comes from America -- it's called tobacco" and "It's a perfectly natural leaf."
** Another Fry and Laurie sketch has a bedtime drink containing "nature's own barbiturates and heroin".
* In ''Series/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 '60s, 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.
* Discussed on ''Series/AdamRuinsEverything'', with regard to breastfeeding vs. baby formula. One of Emily's friends berates her for using formula to feed her baby (who wouldn't latch at the hospital), saying that formula is "baby poison," and also that breastfeeding is the best or only way to bond with baby. Emily's mother-in-law, Patti, with the help of a researcher, shows her that formula is ''not'' toxic (as long as you use clean water and sterile bottles), it saved the lives of many babies whose mothers couldn't breastfeed, and that there's no ''conclusive'' evidence that using formula will adversely affect the baby's IQ or well-being...or that breastfeeding makes a difference in that regard. She and Adam also explain that breastfeeding is not the only way to bond with baby, and that the "love hormone" (oxytocin) is released while doing ''plenty'' of other things than breastfeeding (even things we might consider vices). The researcher explains that the view of formula as "baby poison" goes back to TheSeventies, when [[MegaCorp Nestle]] was marketing formula in poor countries, where clean water was not available, which led to the formula being contaminated by the dirty water, and in turn, a spike in infant death from diseases and parasites. (Not helping matters was the fact that these impoverished mothers were diluting the formula to help it last longer, because it was expensive for them, which led to babies dying of malnutrition as well.) This led to conspiracy theories, and the belief that formula is unsafe because it's artificial.

[[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 perhaps even ''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, while [[DeliberateValuesDissonance purposeful]], can be pretty jarring.
* In ''VideoGame/TelepathTactics'', the anarchist Zimmer tries to invoke this after learning that [[PoliceAreUseless the local constabulary were paid off by their opponents]], but is immediately debunked by [[ScienceHero Phoebe]].
-->'''Zimmer:''' But to be honest, I prefer it this way: individuals duking it out like nature intended, instead of an unaccountable state picking winners and losers...\\
'''Phoebe:''' (''sighing heavily'') Nature does not have intent, Zimmer; it is nothing more than a series of systems. Civilization is no less "natural" than running alone, naked and delirious, through the woods.

[[folder:Web Original]]
* Wiki/TVTropes:
** 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 where there's nothing at stake except "freedom". A big 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, and yet 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 flawed reasons.]]
** Frequently comes up in rants about why NewMediaAreEvil.

[[folder:Real Life]]
* This is often used with regard to social issues; for example, certain more extreme opponents of feminism contend that since the natural order for a great many species (particularly mammals) is for males to be dominant, women should not be granted the same rights as men. Apart from the numerous exceptions to this observation (such as the many matriarchal species of simians and the occasional RealLife OneGenderRace species that reproduce through parthenogenesis such as the whiptail lizard), this contention assumes that nature is what endows us with our rights. Yet historically, nature has never yet been demonstrated to provide any rights ''whatsoever'' to animals, let alone sexual equality. By this "logic" therefore, not only equality, but the rights to life, liberty, and pursuit of happiness would all have to be abolished and we would have to return to a Hobbesian state of total anarchy (in which life is solitary, poor, nasty, brutish, and short) in order to restore men to the "natural" social order in which such dominance arises.
* 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 appeal to nature, right down to claiming a UsefulNotes/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 many modern pesticides and their manufacture are bad for the environment, 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. Ironically, organic farmers ''also'' use pesticides (made of "natural" toxins) which can be ''more'' harmful than synthetic ones since they are subject to far less testing. Additionally organic farming requires far more land use, meaning it could not possibly feed all the people necessary in today's world. The same arguments also apply to [=GMO=]s.
** A shocking amount of people think that organic food is not only better for you but better for the environment. The logic is that all those pest asides must be bad for nature and organic uses less so it must be better. However many people fail to realize that agriculture is ''THE'' single largest threat to the environment simply by the amount of space it takes up. Organic crops lose more of their product to pests so the solution is to simply destroy more natural habitats to plant more. So in an way, and appeal to nature means we have less of it.
* The idea of the superior "NobleSavage" has popped up repeatedly for centuries. The supposed moral superiority of the primitive person or beasts over civilized man has been a repeated assertion of certain philosophical romanticists such as Rousseau. Of course, since NatureIsNotNice, a lot of these "savage" cultures have some 25% of their men dying in war, 20-50% of children failing to survive their childhood, and widespread polygamy (not very popular with these romanticists) in part as a consequence of the imbalance in the sexes resulting from this high mortality rate; not exactly what most of these philosophers would deem desirable outcomes for our cultures. 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 ''Fast Food Nation'': 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 (verbatim) "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, whether its primary effect will do you any good or not), a case of BlatantLies (it's natural, and there are some side effects, but these are just other natural aspects of it) or a case of selective omission (it's all natural, and there ''are'' no side effects. There are no ''primary'' effects either because this is actually just a placebo to help you psychologically while you follow the rest of the instructions we give you. ''Those'' are what will actually make 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" (translated literally as chemistry, but often means "chemicals".).
* 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, octopuses, crows, 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 crapping on 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]]!).
* All sides contending over various sexual issues are guilty of this, claiming either that a given sexual practice is wrong because it's unnatural, or that it's perfectly natural and must therefore be acceptable. The aforementioned ambiguous meaning of "natural" produces a lot of equivocation and question-begging, serving only to cloud these arguments further.
* 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), never mind the fact that polar bears are endangered and this was a big step up in learning how to keep them from dying out. Also, he wasn't ''in'' the wild.
* 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]]. Even if true biologically (which it isn't), that would not make it right.
* 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).
* In UsefulNotes/NaziGermany, propaganda glorified the "natural order" which, according to the Nazis, was that the strong should dominate the weak and that the "master race" should subjugate the "inferior" races. This worldview is illustrated in ''Disney/EducationForDeath'', in which the Nazi teacher uses the story of a fox devouring a rabbit to teach students the "lesson" that the weak ''should'' perish and the strong ''should'' kill and devour them. This argument preceded the Nazis by decades: social Darwinists (from whom the Nazis [[http://www.evolutionnews.org/2016/11/was_darwinism_b103304.html derived much of their curriculum, even though they recommended a ban on a few specific "primitive forms" of Darwinism]]) used the argument to justify many horrible things, like "scientific" racism and eugenics. Indeed, it even preceded Darwinism [[http://scienceblogs.com/primatediaries/2010/01/05/deconstructing-social-darwinis/ itself.]] The argument that MightMakesRight is the natural order of things goes back ''millennia''.
* The pseudoscientific practice of [[https://en.wikipedia.org/wiki/Lunaception Lunaception]] posits that before the advent of artificial lighting, women's menstrual cycles were perfectly synced to the moon's phases, with ovulation taking place at the full moon and menstruation taking place at the new moon (unless, of course, she was pregnant or nursing, or not of reproductive age). The solution to menstrual irregularities and infertility, according to this practice, is to reset the body's clock by eliminating light from the bedroom except during the full moon. Supposedly, it also eliminates the need for artificial contraception, as ovulation is supposed to become more predictable.
* Some of the supporters of [[StayInTheKitchen traditional gender roles and expectations]] (in particular, certain religious leaders), say that women are "oppressed" because they are (supposedly) overwhelmed with all the choices they have, or are unsatisfied with life because they picked options other than what's (supposedly) "natural." (i.e. choosing to go to college instead of marrying right out of HighSchool, choosing to get married [[OldMaid later in life, or not get married at all]], choosing to cohabitate with a partner rather than get legally and formally married, choosing to have children later in life or not have children at all, choosing to have [[CareerVersusFamily a career outside the home]] rather than being a {{Housewife}}, being the primary breadwinner for the household instead of depending on her husband to be the provider, choosing to MarryForLove instead of accepting an ArrangedMarriage based on socioeconomic considerations, etc.)
* This is the reason for the Catholic church's official stance on birth control. They believe that every cell and organ has [[BecauseDestinySaysSo a divinely-ordained natural purpose]], and that the natural purpose of the reproductive organs is, well, [[ExactlyWhatItSaysOnTheTin reproducing]], and that therefore having sex solely or primarily for pleasure (even as a married couple) "cheapens" the act because you're blocking the natural purpose of these organs artificially. (It ''does'' concede that some couples may wish to limit the number of children they have or delay having children, and allows for "natural" methods of birth control, such as the Rhythm Method or the symptothermal method of "natural family planning," on the grounds that these fertility-awareness methods don't introduce artificial barriers or disrupt the natural menstrual cycle.) It takes a dim view of IVF for partially the same reason (the others being the "extra" embryos produced in the process being left in the freezer indefinitely or destroyed, and the possibility of it being a slippery slope to DesignerBabies.)