The explosion of the hydrogen bomb Ivy Mike

Human extinction, also known as omnicide, is the hypothetical

end End, END, Ending, or variation, may refer to: End *In mathematics: ** End (category theory) ** End (topology) **End (graph theory) ** End (group theory) (a subcase of the previous) **End (endomorphism) *In sports and games **End (gridiron footbal ...

of the human species due to either natural causes such as population decline from

sub-replacement fertility Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation being less populous than the older, previous one in a given area. The United Nations Population Division defines sub-replacement fertilit ...

, an

asteroid impact An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have been found to regularly occur in planetary systems, though the most frequent involve asteroids, comets or me ...

, or large-scale volcanism, or to anthropogenic (human) causes. For the latter, some of the many possible contributors include

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

, global nuclear annihilation,

biological warfare Biological warfare, also known as germ warfare, is the use of biological toxins or infectious agents such as bacteria, viruses, insects, and fungi with the intent to kill, harm or incapacitate humans, animals or plants as an act of war. ...

, and

ecological collapse Ecological collapse refers to a situation where an ecosystem suffers a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction. Usually, an ecological collapse is precipitated by a disast ...

. Other scenarios center on emerging technologies, such as advanced artificial intelligence,

biotechnology Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used ...

, or self-replicating nanobots. The scientific consensus is that there is a relatively low risk of near-term human extinction due to natural causes. The likelihood of human extinction through humankind's own activities, however, is a current area of research and debate.

History of thought

Early history of thinking about human extinction

Before the 18th and 19th centuries, the possibility that humans or other organisms could become extinct was viewed with scepticism. It contradicted the

principle of plenitude The principle of plenitude asserts that the universe contains all possible forms of existence. Arthur Oncken Lovejoy, Arthur Lovejoy, a Intellectual history, historian of ideas, was the first to trace the history of this philosophy, philosophically ...

, a doctrine that all possible things exist. The principle traces back to

Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...

, and was an important tenet of Christian theology. Ancient Western philosophers such as

Plato Plato ( ; grc-gre, Πλάτων ; 428/427 or 424/423 – 348/347 BC) was a Greek philosopher born in Athens during the Classical period in Ancient Greece. He founded the Platonist school of thought and the Academy, the first institution ...

, and

Lucretius Titus Lucretius Carus ( , ; – ) was a Roman poet and philosopher. His only known work is the philosophical poem ''De rerum natura'', a didactic work about the tenets and philosophy of Epicureanism, and which usually is translated into En ...

wrote of the end of humankind only as part of a cycle of renewal. Later philosophers such as

Al-Ghazali Al-Ghazali ( – 19 December 1111; ), full name (), and known in Persian-speaking countries as Imam Muhammad-i Ghazali (Persian: امام محمد غزالی) or in Medieval Europe by the Latinized as Algazelus or Algazel, was a Persian poly ...

William of Ockham William of Ockham, OFM (; also Occam, from la, Gulielmus Occamus; 1287 – 10 April 1347) was an English Franciscan friar, scholastic philosopher, apologist, and Catholic theologian, who is believed to have been born in Ockham, a small vil ...

, and

Gerolamo Cardano Gerolamo Cardano (; also Girolamo or Geronimo; french: link=no, Jérôme Cardan; la, Hieronymus Cardanus; 24 September 1501– 21 September 1576) was an Italian polymath, whose interests and proficiencies ranged through those of mathematician, ...

expanded the study of

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premise ...

and

probability Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speakin ...

and began discussing abstract ''possible'' worlds, including a world without humans. Physicist

Edmond Halley Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720. From an observatory he constructed on Saint Helena in 1676–77, H ...

stated that the extinction of the human race may be beneficial to the future of the world. The notion that species can become extinct gained scientific acceptance during the

Age of Enlightenment The Age of Enlightenment or the Enlightenment; german: Aufklärung, "Enlightenment"; it, L'Illuminismo, "Enlightenment"; pl, Oświecenie, "Enlightenment"; pt, Iluminismo, "Enlightenment"; es, La Ilustración, "Enlightenment" was an intel ...

in the 17th and 18th centuries, and by 1800 Georges Cuvier had identified 23 extinct prehistoric species. The doctrine was further gradually undermined by evidence from the natural sciences, particular the discovery of fossil evidence of species that appeared to no longer exist, and the development of theories of evolution. In ''

On the Origin of Species ''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life''),The book's full original title was ''On the Origin of Species by Me ...

'', Darwin discussed the extinction of species as a natural process and core component of natural selection. Notably, Darwin was skeptical of the possibility of sudden extinctions, viewing it as a gradual process. He held that the abrupt disappearances of species from the fossil record were not evidence of catastrophic extinctions, but rather were a function of unrecognised gaps in the record. As the possibility of extinction became more widely established in the sciences, so did the prospect of human extinction. In the 19th century, human extinction became a popular topic in science (e.g.,

Thomas Robert Malthus Thomas Robert Malthus (; 13/14 February 1766 – 29 December 1834) was an English cleric, scholar and influential economist in the fields of political economy and demography. In his 1798 book '' An Essay on the Principle of Population'', Ma ...

's '' An Essay on the Principle of Population'') and fiction (e.g.,

Mary Shelley Mary Wollstonecraft Shelley (; ; 30 August 1797 – 1 February 1851) was an English novelist who wrote the Gothic novel '' Frankenstein; or, The Modern Prometheus'' (1818), which is considered an early example of science fiction. She also ...

's ''

The Last Man ''The Last Man'' is an apocalyptic, dystopian science fiction novel by Mary Shelley, first published in 1826. The narrative concerns Europe in the late 21st century, ravaged by a mysterious plague pandemic that rapidly sweeps across the enti ...

''). In 1863, a few years after

Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended ...

published ''

'', William King proposed that

Neanderthal Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...

s were an extinct species of the genus ''

Homo ''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...

''. The Romantic authors and poets were particularly interested in the topic.

Lord Byron George Gordon Byron, 6th Baron Byron (22 January 1788 – 19 April 1824), known simply as Lord Byron, was an English romantic poet and peer. He was one of the leading figures of the Romantic movement, and has been regarded as among the ...

wrote about the extinction of life on earth in his 1816 poem "

Darkness Darkness, the direct opposite of lightness, is defined as a lack of illumination, an absence of visible light, or a surface that absorbs light, such as black or brown. Human vision is unable to distinguish colors in conditions of very low ...

", and in 1824 envisaged humanity being threatened by a comet impact, and employing a missile system to defend against it.

's 1826 novel ''

'' is set in a world where humanity has been nearly destroyed by a mysterious plague. At the turn of the 20th century,

Russian cosmism Russian cosmism, also cosmism, is a philosophical and cultural movement that emerged in Russia at the turn of the 19th century, and again, at the beginning of the 20th century. At the beginning of the 20th century, there was a burst of scientifi ...

, a precursor to modern

transhumanism Transhumanism is a philosophical and intellectual movement which advocates the enhancement of the human condition by developing and making widely available sophisticated technologies that can greatly enhance longevity and cognition. Transhuma ...

, advocated avoiding humanity's extinction by colonizing space.

Atomic era

The invention of the atomic bomb prompted a wave of discussion about the risk of human extinction among scientists, intellectuals, and the public at large. In a 1945 essay,

Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British mathematician, philosopher, logician, and public intellectual. He had a considerable influence on mathematics, logic, set theory, linguistics, ...

wrote that " e prospect for the human race is sombre beyond all precedent. Mankind are faced with a clear-cut alternative: either we shall all perish, or we shall have to acquire some slight degree of common sense." In 1950,

Leo Szilard Leo Szilard (; hu, Szilárd Leó, pronounced ; born Leó Spitz; February 11, 1898 – May 30, 1964) was a Hungarian-German-American physicist and inventor. He conceived the nuclear chain reaction in 1933, patented the idea of a nuclear ...

suggested it was technologically feasible to build a

cobalt bomb A cobalt bomb is a type of "salted bomb": a nuclear weapon designed to produce enhanced amounts of radioactive fallout, intended to contaminate a large area with radioactive material, potentially for the purpose of radiological warfare, mutual ...

that could render the planet unlivable. A 1950 Gallup poll found that 19% of Americans believed that another world war would mean "an end to mankind".

Rachel Carson Rachel Louise Carson (May 27, 1907 – April 14, 1964) was an American marine biologist, writer, and conservationist whose influential book '' Silent Spring'' (1962) and other writings are credited with advancing the global environmental ...

's 1962 ''

Silent Spring ''Silent Spring'' is an environmental science book by Rachel Carson. Published on September 27, 1962, the book documented the environmental harm caused by the indiscriminate use of pesticides. Carson accused the chemical industry of spreading d ...

'' raised awareness of environmental catastrophe. In 1983,

Brandon Carter Brandon Carter, (born 1942) is an Australian theoretical physicist, best known for his work on the properties of black holes and for being the first to name and employ the anthropic principle in its contemporary form. He is a researcher at th ...

proposed the

Doomsday argument The Doomsday Argument (DA), or Carter catastrophe, is a probabilistic argument that claims to predict the future population of the human species, based on an estimation of the number of humans born to date. The Doomsday argument was originally ...

, which used

Bayesian probability Bayesian probability is an interpretation of the concept of probability, in which, instead of frequency or propensity of some phenomenon, probability is interpreted as reasonable expectation representing a state of knowledge or as quantification ...

to predict the total number of humans that will ever exist. The discovery of "

nuclear winter Nuclear winter is a severe and prolonged global climatic cooling effect that is hypothesized to occur after widespread firestorms following a large-scale nuclear war. The hypothesis is based on the fact that such fires can inject soot into t ...

" in the early 1980s, a specific mechanism by which nuclear war could result in human extinction, again raised the issue to prominence. Writing about these findings in 1983, Carl Sagan argued that measuring the severity of extinction solely in terms of those who die "conceals its full impact", and that nuclear war "imperils all of our descendants, for as long as there will be humans."

Post Cold War

John Leslie's 1996 book ''The End of The World'' was an academic treatment of the science and ethics of human extinction. In it, Leslie considered a range of threats to humanity and what they have in common. In 2003, British

Astronomer Royal Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the junior is the Astronomer Royal for Scotland dating from 1834. The post ...

Sir

Martin Rees Martin John Rees, Baron Rees of Ludlow One or more of the preceding sentences incorporates text from the royalsociety.org website where: (born 23 June 1942) is a British cosmologist and astrophysicist. He is the fifteenth Astronomer Royal, ...

published ''

Our Final Hour ''Our Final Hour'' is a 2003 book by the British Astronomer Royal Sir Martin Rees. The full title of the book is ''Our Final Hour: A Scientist's Warning: How Terror, Error, and Environmental Disaster Threaten Humankind's Future In This Century— ...

'', in which he argues that advances in certain technologies create new threats for the survival of humankind and that the 21st century may be a critical moment in history when humanity's fate is decided. Edited by Nick Bostrom and Milan M. Ćirković, ''

Global Catastrophic Risks A global catastrophic risk or a doomsday scenario is a hypothetical future event that could damage human well-being on a global scale, even endangering or destroying modern civilization. An event that could cause human extinction or permanen ...

'' was published in 2008, a collection of essays from 26 academics on various global catastrophic and existential risks.

Toby Ord Toby David Godfrey Ord (born July 1979) is an Australian philosopher. He founded Giving What We Can in 2009, an international society whose members pledge to donate at least 10% of their income to effective charities, and is a key figure in the ...

's 2020 book '' The Precipice: Existential Risk and the Future of Humanity'' argues that preventing existential risks is one of the most important moral issues of our time. The book discusses, quantifies, and compares different existential risks, concluding that the greatest risks are presented by unaligned artificial intelligence and biotechnology.

Causes

Potential anthropogenic causes of human extinction include global thermonuclear war, deployment of a highly effective

biological weapon A biological agent (also called bio-agent, biological threat agent, biological warfare agent, biological weapon, or bioweapon) is a bacterium, virus, protozoan, parasite, fungus, or toxin that can be used purposefully as a weapon in bioterroris ...

, an ecological collapse, runaway artificial intelligence, runaway nanotechnology (such as a

grey goo Gray goo (also spelled as grey goo) is a hypothetical global catastrophic scenario involving molecular nanotechnology in which out-of-control self-replicating machines consume all biomass on Earth while building many more of themselves, a sce ...

scenario), a scientific accident involving a

micro black hole Micro black holes, also called mini black holes or quantum mechanical black holes, are hypothetical tiny (<1 ) vacuum metastability disaster,

overpopulation Overpopulation or overabundance is a phenomenon in which a species' population becomes larger than the carrying capacity of its environment. This may be caused by increased birth rates, lowered mortality rates, reduced predation or large scal ...

and increased consumption pose the risk of resource depletion and a concomitant population crash, population decline by choosing to have fewer children, displacement of naturally evolved humans by a new species produced by genetic engineering or technological augmentation. Natural and external extinction risks include high-fatality-rate pandemic, supervolcanic

eruption Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...

, nearby supernova or

gamma-ray burst In gamma-ray astronomy, gamma-ray bursts (GRBs) are immensely energetic explosions that have been observed in distant galaxies. They are the most energetic and luminous electromagnetic events since the Big Bang. Bursts can last from ten millise ...

s, extreme

solar flare A solar flare is an intense localized eruption of electromagnetic radiation in the Sun's atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other sol ...

, or

alien invasion The alien invasion or space invasion is a common feature in science fiction stories and film, in which extraterrestrial lifeforms invade the Earth either to exterminate and supplant human life, enslave it under an intense state, harvest people ...

. Without intervention by unexpected forces, the stellar evolution of the Sun is expected to make Earth uninhabitable, then destroy it. Depending on its ultimate fate, the entire universe may eventually become uninhabitable.

Probability

Natural vs. anthropogenic

Experts generally agree that anthropogenic existential risks are (much) more likely than natural risks. A key difference between these risk types is that empirical evidence can place an upper bound on the level of natural risk. Humanity has existed for at least 200,000 years, over which it has been subject to a roughly constant level of natural risk. If the natural risk were high, then it would be highly unlikely that humanity would have survived as long as it has. Based on a formalization of this argument, researchers have concluded that we can be confident that natural risk is lower than 1 in 14,000 (and likely "less than one in 87,000") per year. Another empirical method to study the likelihood of certain natural risks is to investigate the geological record. For example, a comet or asteroid impact event sufficient in scale to cause an

impact winter An impact winter is a hypothesized period of prolonged cold weather due to the impact of a large asteroid or comet on the Earth's surface. If an asteroid were to strike land or a shallow body of water, it would eject an enormous amount of dust, ...

that would cause human extinction before the year 2100 has been estimated at one-in-a-million. Moreover, large supervolcano eruptions may cause a

volcanic winter A volcanic winter is a reduction in global temperatures caused by volcanic ash and droplets of sulfuric acid and water obscuring the Sun and raising Earth's albedo (increasing the reflection of solar radiation) after a large, particularly explosiv ...

that could endanger the survival of humanity. The geological record suggests that supervolcanic eruptions are estimated to occur on average about once every 50,000 years, though most such eruptions would not reach the scale required to cause human extinction. Famously, the supervolcano Mt. Toba may have almost wiped out humanity at the time of its last eruption (though this is contentious). Since anthropogenic risk is a relatively recent phenomenon, humanity's track record of survival cannot provide similar assurances. Humanity has only survived 77 years since the creation of nuclear weapons, and for future technologies, there is no track record at all. This has led thinkers like Carl Sagan to conclude that humanity is currently in a "time of perils" – a uniquely dangerous period in human history, where it is subject to unprecedented levels of risk, beginning from when humans first started posing risk to themselves through their actions.

Risk estimates

Given the limitations of ordinary observation and modeling, expert elicitation is frequently used instead to obtain probability estimates. In 2008, an informal survey of experts at a conference hosted by the

Future of Humanity Institute The Future of Humanity Institute (FHI) is an interdisciplinary research centre at the University of Oxford investigating big-picture questions about humanity and its prospects. It was founded in 2005 as part of the Faculty of Philosophy and t ...

estimated a 19% risk of human extinction by the year 2100, though, given the survey's limitations, these results should be taken "with a grain of salt".

Table source:
Future of Humanity Institute The Future of Humanity Institute (FHI) is an interdisciplinary research centre at the University of Oxford investigating big-picture questions about humanity and its prospects. It was founded in 2005 as part of the Faculty of Philosophy and t ...
, 2008.

There have been a number of other estimates of existential risk, extinction risk, or a global collapse of civilization: * Humanity has a 95% probability of being extinct in 7,800,000 years, according to J. Richard Gott's formulation of the controversial

, which argues that we have probably already lived through half the duration of human history. * In 1996, John Leslie estimated a 30% risk over the next five centuries (equivalent to around 9% per century, on average). * In 2003,

estimated a 50% chance of collapse of civilisation in the twenty-first century. * The

Global Challenges Foundation The Global Challenges Foundation is a Swedish non-profit organization that seeks to raise awareness of global catastrophic risk and the global governance necessary to handle these risks. This includes examining models for UN reform, as well as i ...

's 2016 annual report estimates an annual probability of human extinction of at least 0.05% per year. * A 2016 survey of AI experts found a median estimate of 5% that human-level AI would cause an outcome that was "extremely bad (e.g. human extinction)". * In 2020,

estimates existential risk in the next century at "1 in 6" in his book '' The Precipice: Existential Risk and the Future of Humanity''. * Metaculus users currently estimate a 3% probability of humanity going extinct before 2100. * In a 2010 interview with ''

The Australian ''The Australian'', with its Saturday edition, ''The Weekend Australian'', is a broadsheet newspaper published by News Corp Australia since 14 July 1964.Bruns, Axel. "3.1. The active audience: Transforming journalism from gatekeeping to gatew ...

'', Australian scientist

Frank Fenner Frank John Fenner (21 December 1914 – 22 November 2010) was an Australian scientist with a distinguished career in the field of virology Virology is the scientific study of biological viruses. It is a subfield of microbiology that focus ...

predicted the extinction of the human race within a century, primarily as the result of

human overpopulation Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and exceptional cognitive skills due to a large and complex Human brain, brain. This has enabled the development of ad ...

, environmental degradation and climate change. * According to a 2020 study published in '' Scientific Reports'', if

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...

and resource

consumption Consumption may refer to: *Resource consumption *Tuberculosis, an infectious disease, historically * Consumption (ecology), receipt of energy by consuming other organisms * Consumption (economics), the purchasing of newly produced goods for curren ...

continue at current rates, they could culminate in a "catastrophic collapse in human population" and possibly "an irreversible collapse of our civilization" in the next 20 to 40 years. According to the most optimistic scenario provided by the study, the chances that human civilization survives are smaller than 10%. To avoid this collapse, the study says, humanity should pass from a civilization dominated by the economy to a "cultural society" that "privileges the interest of the ecosystem above the individual interest of its components, but eventually in accordance with the overall communal interest." * Nick Bostrom, a philosopher at the

University of Oxford , mottoeng = The Lord is my light , established = , endowment = £6.1 billion (including colleges) (2019) , budget = £2.145 billion (2019–20) , chancellor ...

known for his work on

existential risk A global catastrophic risk or a doomsday scenario is a hypothetical future event that could damage human well-being on a global scale, even endangering or destroying modern civilization. An event that could cause human extinction or permanen ...

, argues that it would be "misguided" to assume that the probability of near-term extinction is less than 25% and that it will be "a tall order" for the human race to "get our precautions sufficiently right the first time", given that an existential risk provides no opportunity to learn from failure. * Philosopher John Leslie assigns a 70% chance of humanity surviving the next five centuries, based partly on the controversial philosophical

doomsday argument The Doomsday Argument (DA), or Carter catastrophe, is a probabilistic argument that claims to predict the future population of the human species, based on an estimation of the number of humans born to date. The Doomsday argument was originally ...

that Leslie champions. Leslie's argument is somewhat

frequentist Frequentist inference is a type of statistical inference based in frequentist probability, which treats “probability” in equivalent terms to “frequency” and draws conclusions from sample-data by means of emphasizing the frequency or pro ...

, based on the observation that human extinction has never been observed, but requires subjective anthropic arguments. Leslie also discusses the anthropic survivorship bias (which he calls an "observational selection" effect on page 139) and states that the ''

a priori ("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ...

'' certainty of observing an "undisastrous past" could make it difficult to argue that we must be safe because nothing terrible has yet occurred. He quotes

Holger Bech Nielsen Holger Bech Nielsen (born 25 August 1941) is a Danish theoretical physicist and professor emeritus at the Niels Bohr Institute, at the University of Copenhagen, where he started studying physics in 1961. Work Nielsen has made original contribut ...

's formulation: "We do not even know if there should exist some extremely dangerous decay of say the proton which caused the eradication of the earth, because if it happens we would no longer be there to observe it and if it does not happen there is nothing to observe." * Jean-Marc Salotti calculated the probability of human extinction caused by a giant asteroid impact. It is between 0.03 and 0.3 for the next billion years, if there is no colonization of other planets. According to that study, the most frightening object is a giant long period comet with a warning time of a few years only and therefore no time for any intervention in space or settlement on the Moon or Mars. The probability of a giant comet impact in the next hundred years is 2.2E-12.

Individual vs. species risks

Although existential risks are less manageable by individuals than – for example – health risks, according to Ken Olum,

Joshua Knobe Joshua Michael Knobe (born 1974) is an American experimental philosopher, whose work ranges across issues in philosophy of mind and action and ethics. He is Professor of Cognitive Science and Philosophy at Yale University. He is known for his w ...

, and Alexander Vilenkin, the possibility of human extinction ''does'' have practical implications. For instance, if the "universal"

is accepted it changes the most likely source of disasters, and hence the most efficient means of preventing them. They write: "... you should be more concerned that a large number of asteroids have not yet been detected than about the particular orbit of each one. You should not worry especially about the chance that some specific nearby star will become a supernova, but more about the chance that supernovas are more deadly to nearby life than we believe."

Difficulty

Some scholars argue that certain scenarios such as global thermonuclear war would have difficulty eradicating every last settlement on Earth. Physicist Willard Wells points out that any credible extinction scenario would have to reach into a diverse set of areas, including the underground subways of major cities, the mountains of Tibet, the remotest islands of the South Pacific, and even to McMurdo Station in Antarctica, which has contingency plans and supplies for long isolation. In addition, elaborate bunkers exist for government leaders to occupy during a nuclear war. The existence of

nuclear submarine A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. Nuclear submarines have considerable performance advantages over "conventional" (typically diesel-electric) submarines. Nuclear propulsion, ...

s, which can stay hundreds of meters deep in the ocean for potentially years at a time, should also be considered. Any number of events could lead to a massive loss of human life, but if the last few (see

minimum viable population Minimum viable population (MVP) is a lower bound on the population of a species, such that it can survive in the wild. This term is commonly used in the fields of biology, ecology, and conservation biology. MVP refers to the smallest possible siz ...

) most resilient humans are unlikely to also die off, then that particular human extinction scenario may not seem credible.

Ethics

Value of human life

Placard against human extinction, Extinction Rebellion (cropped)

"Existential risks" are risks that threaten the entire future of humanity, whether by causing human extinction or by otherwise permanently crippling human progress. Multiple scholars have argued based on the size of the "cosmic endowment" that because of the inconceivably large number of potential future lives that are at stake, even small reductions of existential risk have great value. In one of the earliest discussions of ethics of human extinction, Derek Parfit offers the following thought experiment: The scale of what is lost in an existential catastrophe is determined by humanity's long-term potential – what humanity could expect to achieve if it survived. From a

utilitarian In ethical philosophy, utilitarianism is a family of normative ethical theories that prescribe actions that maximize happiness and well-being for all affected individuals. Although different varieties of utilitarianism admit different charac ...

perspective, the value of protecting humanity is the product of its duration (how long humanity survives), its size (how many humans there are over time), and its quality (on average, how good is life for future people). On average, species survive for around a million years before going extinct. Parfit points out that the Earth will remain habitable for around a billion years. And these might be lower bounds on our potential: if humanity is able to expand beyond Earth, it could greatly increase the human population and survive for trillions of years. The size of the foregone potential that would be lost, were humanity to become extinct, is very large. Therefore, reducing existential risk by even a small amount would have a very significant moral value. Carl Sagan wrote in 1983: "If we are required to calibrate extinction in numerical terms, I would be sure to include the number of people in

future generations Future generations are cohorts of hypothetical people not yet born. Future generations are contrasted with current and past generations, and evoked in order to encourage thinking about intergenerational equity. The moral patienthood of future g ...

who would not be born.... (By one calculation), the stakes are one million times greater for extinction than for the more modest nuclear wars that kill "only" hundreds of millions of people. There are many other possible measures of the potential loss – including culture and science, the evolutionary history of the planet, and the significance of the lives of all of our ancestors who contributed to the future of their descendants. Extinction is the undoing of the human enterprise." Philosopher Robert Adams in 1989 rejects Parfit's "impersonal" views but speaks instead of a moral imperative for loyalty and commitment to "the future of humanity as a vast project... The aspiration for a better society – more just, more rewarding, and more peaceful... our interest in the lives of our children and grandchildren, and the hopes that they will be able, in turn, to have the lives of their children and grandchildren as projects." Philosopher Nick Bostrom argues in 2013 that preference-satisfactionist, democratic, custodial, and intuitionist arguments all converge on the common-sense view that preventing existential risk is a high moral priority, even if the exact "degree of badness" of human extinction varies between these philosophies. Parfit argues that the size of the "cosmic endowment" can be calculated from the following argument: If Earth remains habitable for a billion more years and can sustainably support a population of more than a billion humans, then there is a potential for 10 (or 10,000,000,000,000,000) human lives of normal duration.Parfit, D. (1984)

Reasons and Persons ''Reasons and Persons'' is a 1984 book by the philosopher Derek Parfit, in which the author discusses ethics, rationality and personal identity. It is divided into four parts, dedicated to self-defeating theories, rationality and time, personal ...

. Oxford: Clarendon Press. pp. 453–454 Bostrom goes further, stating that if the universe is empty, then the accessible universe can support at least 10 biological human life-years; and, if some humans were uploaded onto computers, could even support the equivalent of 10 cybernetic human life-years. Some economists and philosophers have defended views, including

exponential discounting In economics exponential discounting is a specific form of the discount function, used in the analysis of choice over time (with or without uncertainty). Formally, exponential discounting occurs when total utility is given by :U(\_^)=\sum_^\del ...

and person-affecting views of population ethics, on which future people do not matter (or matter much less), morally speaking. While these views are controversial, even they would agree that an existential catastrophe would be among the worst things imaginable. It would cut short the lives of eight billion presently existing people, destroying all of what makes their lives valuable, and most likely subjecting many of them to profound suffering. So even setting aside the value of future generations, there may be strong reasons to reduce existential risk, grounded in concern for presently existing people. Beyond utilitarianism, other moral perspectives lend support to the importance of reducing existential risk. An existential catastrophe would destroy more than just humanity – it would destroy all cultural artifacts, languages, and traditions, and many of the things we value. So moral viewpoints on which we have duties to protect and cherish things of value would see this as a huge loss that should be avoided. One can also consider reasons grounded in duties to past generations. For instance,

Edmund Burke Edmund Burke (; 12 January NS.html"_;"title="New_Style.html"_;"title="/nowiki>New_Style">NS">New_Style.html"_;"title="/nowiki>New_Style">NS/nowiki>_1729_–_9_July_1797)_was_an_NS.html"_;"title="New_Style.html"_;"title="/nowiki>New_Style">N ...

writes of a "partnership ... between those who are living, those who are dead, and those who are to be born". If one takes seriously the debt humanity owes to past generations, Ord argues the best way of repaying it might be to 'pay it forward', and ensure that humanity's inheritance is passed down to future generations. There are several economists who have discussed the importance of global catastrophic risks. For example,

Martin Weitzman Martin Lawrence Weitzman (April 1, 1942 – August 27, 2019) was an economist and a professor of economics at Harvard University. He was among the most influential economists in the world according to Research Papers in Economics (RePEc). His late ...

argues that most of the expected economic damage from climate change may come from the small chance that warming greatly exceeds the mid-range expectations, resulting in catastrophic damage.

Richard Posner Richard Allen Posner (; born January 11, 1939) is an American jurist and legal scholar who served as a federal appellate judge on the U.S. Court of Appeals for the Seventh Circuit from 1981 to 2017. A senior lecturer at the University of Chic ...

has argued that humanity is doing far too little, in general, about small, hard-to-estimate risks of large-scale catastrophes.

Voluntary extinction

Voluntary Human Extinction Movement - motto

Some philosophers adopt the antinatalist position that human extinction would not be a bad thing, but a good thing.

David Benatar David Benatar (born 8 December 1966) is a South African philosopher, academic and author. He is best known for his advocacy of antinatalism in his book '' Better Never to Have Been: The Harm of Coming into Existence'', in which he argues that ...

argues that coming into existence is always serious harm, and therefore it is better that people do not come into existence in the future. Further, David Benatar, animal rights activist Steven Best, and anarchist

Todd May Todd Gifford May (born May 13, 1955) is a political philosopher who writes on topics of anarchism, poststructuralism, and post-structuralist anarchism. More recently he has published books on existentialism and moral philosophy. He is currentl ...

, posit that human extinction would be a positive thing for the other organisms on the planet, and the planet itself, citing, for example, the omnicidal nature of human civilization. The environmental view in favor of human extinction is shared by the members of Voluntary Human Extinction Movement who call for refraining from reproduction and allowing the human species to go peacefully extinct, thus stopping further environmental degradation.

In fiction

Jean-Baptiste Cousin de Grainville Jean-Baptiste François Xavier Cousin De Grainville (3 April 1746 – 1 February 1805) was a French writer who wrote a seminal work of fantasy literature: '' Le Dernier Homme'' (''The Last Man'') (1805). This was the first modern novel to depict ...

's 1805 ''Le dernier homme'' (''The Last Man''), which depicts human extinction due to infertility, is considered the first modern apocalyptic novel and credited with launching the genre. Other notable early works include

's 1826 ''

'', depicting human extinction caused by a pandemic, and

Olaf Stapledon William Olaf Stapledon (10 May 1886 – 6 September 1950) – known as Olaf Stapledon – was a British philosopher and author of science fiction.Andy Sawyer, " illiamOlaf Stapledon (1886-1950)", in Bould, Mark, et al, eds. ''Fifty Key Figures ...

's 1937 '' Star Maker'', "a comparative study of omnicide". Some 21st century pop-science works, including '' The World Without Us'' by Alan Weisman, and the TV specials ''

Life After People ''Life After People'' is a television series on which scientists, mechanical engineers, and other experts speculate about what might become of planet Earth if humanity suddenly disappeared. The featured experts also talk about the impact of hu ...

'' and '' Aftermath: Population Zero'' pose a

thought experiment A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. History The ancient Greek ''deiknymi'' (), or thought experiment, "was the most anc ...

: what would happen to the rest of the planet if humans suddenly disappeared? A threat of human extinction, such as through a

technological singularity The technological singularity—or simply the singularity—is a hypothetical future point in time at which technological growth becomes uncontrollable and irreversible, resulting in unforeseeable changes to human civilization. According to the m ...

(also called an intelligence explosion), drives the plot of innumerable science fiction stories; an influential early example is the 1951 film adaption of ''

When Worlds Collide ''When Worlds Collide'' is a 1933 science fiction novel co-written by Edwin Balmer and Philip Wylie; they also co-authored the sequel ''After Worlds Collide'' (1934). It was first published as a six-part monthly serial (September 1932 through Fe ...

''. Usually the extinction threat is narrowly avoided, but some exceptions exist, such as ''

R.U.R. ''R.U.R.'' is a 1920 science-fiction play by the Czech writer Karel Čapek. "R.U.R." stands for (Rossum's Universal Robots, a phrase that has been used as a subtitle in English versions). The play had its world premiere on 2 January 1921 in H ...

'' and Steven Spielberg's ''

A.I. Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech rec ...

References

Sources

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History of thought

Early history of thinking about human extinction

Atomic era

Post Cold War

Causes

Probability

Natural vs. anthropogenic

Risk estimates

Individual vs. species risks

Difficulty

Ethics

Value of human life

Voluntary extinction

In fiction

See also

References

Sources

Further reading