|Some dare call it|
Conspiracy theories about depopulation of the Earth come in a number of flavors. The general theme running through these theories is either that there is an imminent plan to reduce population using an overpopulation crisis as the pretext, or a secret eugenics plan cover-up. The elite thus need to kill off the "useless eaters" so, in the first case, they survive the crisis and, in the second, they can create either enough robots to replace them, or a new race of obedient super-humans.
 Useless eaters
"Useless eaters" is a term often bandied about by conspiracy theorists. This is supposedly what the heads of the New World Order/Illuminati/Bilderbergs/Reptoids/whatevercall us in their meetings in smoke-filled rooms while they light their cigars with $100 bills. It is also sometimes used by survivalists and wrongly attributed to Henry Kissinger. It is also commonly ascribed to Ted Turner, Adolf Hitler, Thomas Malthus, and Bertrand Russell. Apparently, the term originated in Nazi Germany during the Holocaust as "unnütze esser," translating to "useless eaters."  It was first used in reference to the T4 euthanasia program; which targeted the incurably ill, physically or mentally disabled, emotionally distraught, and elderly people. 
 Means of execution
The genocidal depopulation plan generally involves poisoning or sterilizing people through the use of chemtrails or water fluoridation. Agribusiness transnationals like Monsanto are often implicated in some sort of scheme to monopolize the world's food supply so it can be easily tainted with deadly toxins. Just about anything that can be said to involve "chemicals" can be implicated in this nefarious scheme: vaccines, alleged covert geo-engineering schemes, genetically modified food, etc. Variants of the theory include those with an anti-abortion tinge who incorporate conspiracy theories about Planned Parenthood, and AIDS conspiracy theorists who believe AIDS was concocted in a laboratory for the purpose of reducing the population. Another variant, largely attributable to Lyndon LaRouche, has worldwide nuclear war as part of the conspirators' alleged plan along with a deliberate economic collapse and de-industrialization to force the world back into a "new dark age."
 Anti-environmentalist theories
A number of these theories have an anti-environmentalist bent. They posit that environmentalists are conspiring as some kind of mass Gaia cult to kill off the useless eaters. There is a very tiny grain of truth here when it comes to the really nutty ecoterrorists, Pentti Linkola, or movements like the Voluntary Human Extinction Movement, which provide generous amounts of fodder for conspiracy sites to use as a means to paint the entire environmental movement as a mass conspiracy. This usually ties into some form of a global warming conspiracy theory or the idea that fears of overpopulation are being used as a tactic to implement the depopulation scheme. The Club of Rome and their book The Limits to Growth, and Paul R. Ehrlich and his book The Population Bomb are the convenient punching bags here.
 Negative effects
Supporters of this theory often fail to understand the negative effects of depopulation and low populations. Fewer people will mean a smaller work force, strengthening the hand of those remaining, resulting in friction between labour and management. There will be fewer soldiers to have a strong military, meaning it will become harder to adequately maintain the safety of society. Above all though is that with fewer people the structure of government would grow unstable, and would eventually collapse.
It's also worth noting that economically there would be consequences as well. As many developed countries use capitalism, an economic system which is dependent on human growth, then heavy depopulation would mean financial disaster resulting in a volatile market. Adam Smith famously established that it is an imperative for economies, especially those using capitalism, to maintain stability. This is provably true in places like Japan whose negative population growth is contributing to its current economic woes.
These effects pose a big question: why would a government seek to heavily depopulate the planet when doing so is provably harmful to its interests and a healthy existence? If they really do desire this then the answer would have to be that they're gluttons for punishment.
 Consider the Following
Governments (intelligent ones) have implemented policies and practices to encourage population growth or discourage it. In America for example, the more children people have, the more benefits the parents are entitled to. That makes one wonder why a government that's supposedly involved in some grand plot to depopulation is trying to get people to have more children and not less. Conspiracy theorists are commonly reticent in trying to explain that or wave it off saying it's some kind of cover.
As for places that discourage it, theorists are more passionate in demeaning places like China citing their policies as central to the depopulation plot. In China's case, their attempts to curtail the population was caused, rather humorously, by the government of Mao Zedong in encouraging its citizens to have as many children as possible. Their strategies often included discouraging the use of birth control to the point they banned the import of contraceptives into their country.
The eventual boom in population naturally resulted in a hugely overpopulated country China was unable to cope with. By the 1950s China's food supply was struggling to maintain the influx of new children. This is one of the main reasons behind the infamous 1962 famine that resulted in the deaths of approximately 30 million people. The event resulted in the government going "shit, guess the 'have as many kids possible' thing wasn't smart after all."
In a desperate attempt to get the population back down to a stable, healthy level they could handle, the government began to use propaganda urging citizens to limit the number of children they had. Given selfish human nature, many of its citizens gave a huge middle finger and continued to procreate without restraint. Tired of being blanked, the government, desperate to end its overpopulation problem, enacted the one-child policy to forcefully bring its population back down to a stable level. 
But that has begun to change. China's population level has decreased to a below stable level, the government is beginning to do a 180 degree switch on the policy. Problems such as a lack of a stable workforce and a low male ratio has resulted in the one-child policy being revised. People are beginning to gain more leeway in having more than one child. The People's Republic of China has dropped huge suggestions it will go further in its revisions to encourage more children be born. 
So that begs a question: if places like China wanted to depopulate the planet so badly why wouldn't they remain adamant in not changing their policies?
Answer: such actions show that governments definitely do not want overpopulation yet, at the same time, definitely don't want underpopulation either. They need a stable population if they are to survive.
 And When Populations Get Too Low...
Governments have taken other extreme measures to combat low populations as well. A notable example is Russia's infamous tax on childless persons enacted during the reign of Joseph Stalin - yes, you read that right, that Stalin - to financially strong arm people to procreate to boost its low birthrate. The government even went so far as to give medals and honorary titles to women for having large families.
Such policies, despite their unpopularity amongst an already miserable populace, was a resounding success. It was so successful that it caused Russia's birthrate to exceed the government's initial expectations. Satisfied the population was stable once more, the tax was phased out not to mention many of the benefits that came with having lots of children.
The currently deteriorating conditions after the fall of the Soviet Union have caused birthrates to plunge again. The idea of bringing back the tax was again put on the table in 2006 with Vladimir Putin adding that women should be paid more money to have a second child. To the relief of the childless and childfree in the country, these plans have not been put into effect. They are in a holding pattern however given the still decreasing birthrate.
Other governments have gone even further in their attempts to have stable populations. Nazi Germany began a campaign to quell the low birthrate that preceded its rise to power and which existed during its infancy. Besides given out benefits to people who gave birth, the government banned and heavily punished those who used contraception, abortion and homosexuality. Death was one of the most extreme punishments delivered. Furthermore the rights and benefits of childless people were greatly diminished resulting in people, especially women, being legally bullied to give birth. Those who did comply often got tremendous benefits including, like in the Soviet Union, medals for raising large families.
And if these past examples aren't evidence enough that governments don't want populations getting too small, the government of Iran previously encouraged people to have less children starting around 1989 to combat a boom in their population lasting from 1976-1996. The policies have until now been successful resulting in a noticeably smaller birthrate. The government has since been cutting funding to the programs to facilitate lower birthrates to boost what they feel is a population too small for their liking. For example: vasectomies, once free, have ended due to the government cutting moneyflow. The government plans to go even further showing very keen interest in banning vasectomies altogether and making it tougher, if not near-impossible, for women to get abortions and people to use contraceptives.
Japans birthrate reached an all time low in 2005, prompting the creation of a ministerial bureau in the Cabinet Office to specifically address the issue. The Ministry of State for Declining Birthrate and Gender Equality believes greater gender equality in the workplace the most effective method of encouraging births and promotes tax reductions and longer periods of paid leave following the birth of a child. 
 So What Does That All Mean?
That isn't the kind of behavior governments display if they are intent on depopulation. The above mentioned governments specifically are infamous for their crimes against humanity yet never once went so far as to embrace depopulation but still strove to have stable populations.
This brings us back full circle to the previously established fact that without a stable population governments will suffer. But it shows that they do have one provably real agenda going on and that is a stable population agenda.
A depopulation plot, all things considered, doesn't seem at all likely.
 But What If It Is?
If there's an evil plot then the governments involved then they are obviously quite happy to commit suicide as people are their greatest resource. Too many or too few human beings are devastating to them given the numerous ill-effects mostly especially in regards to their political structure and economies. So if there is a depopulation plot then the people in charge of it are obviously happy to tank their financial systems and destroy the worker based which is essential to keeping a work based society alive.
And considering the lower population, it would be highly unlikely that any huge government could remain big without repercussions. Governments have grown in size in reflection of growing populations. The inverse would have to be true as a lack of people would mean less people to run the government. If there are plans to enact a one-world government in the wake of a depopulation, it'll sure as hell be a damn small one lacking power or clout.
 Possible origins
Fears of this sort may have been stoked by science fiction such as the 1973 film Soylent Green, the 1976 film Logan's Run, by Garrett Hardin proposing rich Western nations practice "lifeboat ethics" in refusing immigration (not a very liberal view, eh?) and by real examples of governments which put radical depopulation into practice, such as Pol Pot's Cambodia between 1975-1979. However, as a conspiracy theory, the scope of the depopulation plan is global, with various conspirators (the Rockefellers, the Club of Rome, Henry Kissinger, British royalty) claimed to be secretly working to reduce the world population by as much as 80 percent.
 See also
- Genocide conspiracy
- HIV denial: There is some overlap between depopulation conspiracy believers and people who believe AIDS is a government-created mechanism for depopulation.
- Pacte de famine: The idea's French predecessor.
- Georgia Guidestones Mysterious monument calling for the world population to fall below 500,000,000 people.
- The Philosophy of Useless Eaters at Rense (Warning: Toxic levels of bullshit)
- ↑ The Depopulation Conspiracy articles, Whale.to (Scopie's Law in effect here)
- ↑ See here.
- ↑ http://www.britannica.com/EBchecked/topic/714411/T4-Program
- ↑ Geo-Engineering: Killing Off the Useless Eaters, Alex Jones
- ↑ Depopulation by Vaccines, Respectful Insolence
- ↑ Global Warming Provides Cover for Depopulating the Earth, The "Truth" Seeker
- ↑ Chapter 8 in the Wealth of Nations, Adam Smith
- ↑ The United Nations is concerned with Japan's low population. Ironic considering many theorists believe they're part of the conspiracy.
- ↑ Time - A Brief History of China's One-Child Policy
- ↑ CNBC - China economy to ride on changes to one-child policy
- ↑ http://soviet-awards.com/medals26.htm
- ↑ Russia Profile - Childfree at a Price
- ↑ Pravada.ru - Childless Russian families to pay taxes for their social inaction
- ↑ http://en.wikipedia.org/wiki/Cross_of_Honour_of_the_German_Mother
- ↑ http://www.csmonitor.com/World/Middle-East/2014/0515/Iran-ends-free-vasectomies-with-maximum-baby-push
- ↑ http://www.theguardian.com/world/2014/apr/15/iran-ban-vasectomies-birthrate
- ↑ http://www.dijtokyo.org/publications/WP0604-%20Schad.pdf