The mediocrity principle is the

philosophical Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. Some ...

notion that "if an item is drawn at random from one of several sets or categories, it's more likely to come from the most numerous category than from any one of the less numerous categories". The principle has been taken to suggest that there is nothing very unusual about the

evolution of the Solar System The formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a ...

Earth's history The history of Earth concerns the development of planet Earth from its formation to the present day. Nearly all branches of natural science have contributed to understanding of the main events of Earth's past, characterized by constant geologic ...

, the

evolution of biological complexity The evolution of biological complexity is one important outcome of the process of evolution. Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biolog ...

human evolution Human evolution is the evolutionary process within the history of primates that led to the emergence of ''Homo sapiens'' as a distinct species of the hominid family, which includes the great apes. This process involved the gradual development of ...

, or any one

nation A nation is a community of people formed on the basis of a combination of shared features such as language, history, ethnicity, culture and/or society. A nation is thus the collective identity of a group of people understood as defined by those ...

. It is a

heuristic A heuristic (; ), or heuristic technique, is any approach to problem solving or self-discovery that employs a practical method that is not guaranteed to be optimal, perfect, or rational, but is nevertheless sufficient for reaching an immediate, ...

in the vein of the

Copernican principle In physical cosmology, the Copernican principle states that humans, on the Earth or in the Solar System, are not privileged observers of the universe, that observations from the Earth are representative of observations from the average position ...

, and is sometimes used as a philosophical statement about the place of humanity. The idea is to assume mediocrity, rather than starting with the assumption that a phenomenon is special, privileged, exceptional, or even

superior Superior may refer to: *Superior (hierarchy), something which is higher in a hierarchical structure of any kind Places *Superior (proposed U.S. state), an unsuccessful proposal for the Upper Peninsula of Michigan to form a separate state *Lake ...

Extraterrestrial life

The mediocrity principle suggests, given the existence of life on Earth, that should

life Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energ ...

exist elsewhere in the

universe The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...

, it will typically exist on Earth-like planets.

Measurement of distance to stars

The mediocrity principle was implicitly applied during the 17th century, when astronomers attempted to measure the distance between distant

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

s and the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. By assuming that the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

was just an average star, and that some stars seemed brighter simply because they were closer to us, they were able to estimate how far these stars were from the Earth. Although this method was flawed in view of the differences among stars, it gave astronomers at that time a rough idea of how far the stars were from the Earth. For example, James Gregory,

Isaac Newton Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, theologian, and author (described in his time as a "natural philosopher"), widely recognised as one of the grea ...

and

Christiaan Huygens Christiaan Huygens, Lord of Zeelhem, ( , , ; also spelled Huyghens; la, Hugenius; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor, who is regarded as one of the greatest scientists of ...

were able to estimate the distance between

Sirius Sirius is the list of brightest stars, brightest star in the night sky. Its name is derived from the Ancient Greek language, Greek word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinisation ...

and the Earth through this method.

Comparison with other approaches

The mediocrity principle is in contrast with the

anthropic principle The anthropic principle, also known as the "observation selection effect", is the hypothesis, first proposed in 1957 by Robert Dicke, that there is a restrictive lower bound on how statistically probable our observations of the universe are, beca ...

, which asserts that the presence of an intelligent observer (humans) limits the circumstances to bounds under which intelligent life can be observed to exist, no matter how improbable. Both stand in contrast to the fine-tuning hypothesis, which asserts that the natural conditions for intelligent life are implausibly rare. The mediocrity principle implies that Earth-like environments are necessarily common, based in part on the evidence of any happening at all, whereas the anthropic principle suggests that no assertion can be made about the probability of intelligent life based on a sample set of one ( self-described) example, who are necessarily capable of making such an assertion about themselves. It is also possible to handle the Mediocrity Principle as a statistical problem, a case of a single

Data point In statistics, a unit of observation is the unit described by the data that one analyzes. A study may treat groups as a unit of observation with a country as the unit of analysis, drawing conclusions on group characteristics from data collected at ...

statistics, also present in the

German tank problem In the statistical theory of estimation theory, estimation, the German tank problem consists of estimating the maximum of a discrete uniform distribution from sampling without replacement. In simple terms, suppose there exists an unknown number o ...

Longevity estimation

The mediocrity principle can also be used to estimate the future

life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...

of presently observable objects, and is especially useful when no hard

data In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted ...

is available.

Richard Gott Richard Willoughby Gott (born 28 October 1938),Winchester College: A Register. Edited by P.S.W.K. McClure and R.P. Stevens, on behalf of the Wardens and Fellows of Winchester College. 7th edition, 2014. pp. 271 (Short Half 1952 list heading) & ...

extended the mediocrity principle to argue that if there is nothing special about observing an object in the present moment (T_now), then one can expect the present moment to occur randomly between the start (T_start) and the end (T_end) of the observed object's longevity. Therefore, the total longevity of an observable object can be expected (with 50% confidence) to lie in the interval 1/3 ⋅ T_start < T_now < 3 ⋅ T_end. This estimation technique was derived after a 1969 visit to the

Berlin Wall The Berlin Wall (german: Berliner Mauer, ) was a guarded concrete barrier that encircled West Berlin from 1961 to 1989, separating it from East Berlin and East Germany (GDR). Construction of the Berlin Wall was commenced by the government ...

, which was constructed eight years prior. Gott reasoned that there was nothing special about the timing of his visit, so the above equation (with T = 8) estimates that the Berlin Wall would last for at least 2.67 years but would last no longer than 24 years (the Berlin Wall fell 22 years later, in 1991).

Longevity estimation reflects the

maxim Maxim or Maksim may refer to: Entertainment * ''Maxim'' (magazine), an international men's magazine ** ''Maxim'' (Australia), the Australian edition ** ''Maxim'' (India), the Indian edition *Maxim Radio, ''Maxim'' magazine's radio channel on Sir ...

"old things tend to last and new things tend to disappear." Most applications of longevity estimation use a 95% confidence interval, which decreases the precision of the estimate by drastically increasing the interval of estimation. One useful estimation made on this confidence interval is the survival of

homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

, which are thought to have emerged around 200,000 years ago. If there is nothing special about our observation of

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

now, in the 21st century, then longevity estimation (with T = 200,000 and a confidence interval of 95%) yields a projected timespan of between 5,100 and 7.8 million years during which the human species will be extant. Some other projected lifespans (with 95% confidence) include

industrial technology Industrial technology is the use of engineering and manufacturing technology to make production faster, simpler, and more efficient. The industrial technology field employs creative and technically proficient individuals who can help a company ach ...

(estimated to last somewhere between 7 years and 10,000 years), the

internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...

(between 7 months and 975 years), and

Wikipedia Wikipedia is a multilingual free online encyclopedia written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and using a wiki-based editing system. Wikipedia is the largest and most-read refer ...

(between 6 months and 772 years). Jim Holt analyzed longevity estimation and concluded that our understanding of

humor Humour (English in the Commonwealth of Nations, Commonwealth English) or humor (American English) is the tendency of experiences to provoke laughter and provide amusement. The term derives from the humorism, humoral medicine of the ancient Gre ...

and

number A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers c ...

will survive for at least one million years. Humans share these traits with other species, which implies we share these traits with some

common ancestor Common descent is a concept in evolutionary biology applicable when one species is the ancestor of two or more species later in time. All living beings are in fact descendants of a unique ancestor commonly referred to as the last universal comm ...

that lived millions of years ago.

Other uses

David Deutsch David Elieser Deutsch ( ; born 18 May 1953) is a British physicist at the University of Oxford. He is a Visiting Professor in the Department of Atomic and Laser Physics at the Centre for Quantum Computation (CQC) in the Clarendon Laboratory of ...

argues that the mediocrity principle is incorrect from a physical point of view, in reference to either humanity's part of the universe or to its species. Deutsch refers to Stephen Hawking's quote: "The human race is just a chemical scum on a moderate-sized planet, orbiting around a very average star in the outer suburb of one among a hundred

billion Billion is a word for a large number, and it has two distinct definitions: *1,000,000,000, i.e. one thousand million, or (ten to the ninth power), as defined on the short scale. This is its only current meaning in English. * 1,000,000,000,000, i.e ...

galaxies". Deutsch wrote that Earth's neighborhood in the universe is not typical (80% of the universe's matter is

dark matter Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not ab ...

) and that a concentration of mass such as the Solar System is an "isolated, uncommon phenomenon". He also disagrees with

Richard Dawkins Richard Dawkins (born 26 March 1941) is a British evolutionary biologist and author. He is an emeritus fellow of New College, Oxford and was Professor for Public Understanding of Science in the University of Oxford from 1995 to 2008. An ath ...

, who considers that humans, because of natural evolution, are limited to the capabilities of their species. Deutsch responds that even though evolution did not give humans the ability to detect

neutrino A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...

s, scientists can currently detect them, which significantly expands their capabilities beyond what is available as a result of evolution.

Notes

References

* Gonzalez, Richards, ''The Privileged Planet: How Our Place in the Cosmos is Designed for Discovery'', Regnery Publishing,

2004 2004 was designated as an International Year of Rice by the United Nations, and the International Year to Commemorate the Struggle Against Slavery and its Abolition (by UNESCO). Events January * January 3 – Flash Airlines Flight 6 ...

, * Peter Ward and

Donald Brownlee Donald Eugene Brownlee (born December 21, 1943) is a professor of astronomy at the University of Washington at Seattle and the principal investigator for NASA's Stardust mission. In 2000, along with his co-author Peter Ward, he co-originated the ...

, '' Rare Earth: Why Complex Life is Uncommon in the Universe'', Copernicus Books, January

2000 File:2000 Events Collage.png, From left, clockwise: Protests against Bush v. Gore after the 2000 United States presidential election; Heads of state meet for the Millennium Summit; The International Space Station in its infant form as seen from ...

, *

J. Richard Gott III John Richard Gott III (born February 8, 1947) is a professor of astrophysics, astrophysical sciences at Princeton University. He is known for his work on time travel and the Doomsday argument. Exotic matter time travel theories Paul Davies's ...

, ''Implications of the Copernican principle for our future prospects'', Nature. 363: 315-319. May 1993 * Jim Holt, '' When Einstein Walked with Gödel: Excursions to the Edge of Thought'', Farrar, Straus and Giroux, May

2015 File:2015 Events Collage new.png, From top left, clockwise: Civil service in remembrance of November 2015 Paris attacks; Germanwings Flight 9525 was purposely crashed into the French Alps; the rubble of residences in Kathmandu following the Apri ...

External links

Goodwin, Gribbin, and Hendry's 1997 Hubble Parameter measurement relying on the mediocrity principle
The authors call this the 'Principle of Terrestrial Mediocrity' even though the assumption they make is that the Milky Way ''Galaxy'' is typical (rather than Earth). This term was coined by

Alexander Vilenkin Alexander Vilenkin (russian: Алекса́ндр Виле́нкин; uk, Олександр Віленкін; born 13 May 1949) is the Leonard Jane Holmes Bernstein Professor of Evolutionary Science and Director of the Institute of Cosmology a ...

(1995). {{DEFAULTSORT:Mediocrity Principle Earth Philosophy of science Principles Search for extraterrestrial intelligence