The Sagan standard is a

neologism A neologism Greek νέο- ''néo''(="new") and λόγος /''lógos'' meaning "speech, utterance"] is a relatively recent or isolated term, word, or phrase that may be in the process of entering common use, but that has not been fully accepted int ...

abbreviating the

aphorism An aphorism (from Greek ἀφορισμός: ''aphorismos'', denoting 'delimitation', 'distinction', and 'definition') is a concise, terse, laconic, or memorable expression of a general truth or principle. Aphorisms are often handed down by ...

that "''extraordinary claims require extraordinary evidence''" (ECREE). It is named after

science communicator Science communication is the practice of informing, educating, raising awareness of science-related topics, and increasing the sense of wonder about scientific discoveries and arguments. Science communicators and audiences are ambiguously def ...

Carl Sagan who used the exact phrase on his television program ''

Cosmos The cosmos (, ) is another name for the Universe. Using the word ''cosmos'' implies viewing the universe as a complex and orderly system or entity. The cosmos, and understandings of the reasons for its existence and significance, are studied in ...

''. Similar statements were previously made by figures such as

Théodore Flournoy Théodore Flournoy (15 August 1854 – 5 November 1920) was a Swiss professor of psychology at the University of Geneva and author of books on parapsychology and spiritism. He studied a wide variety of subjects before he devoted his life to psych ...

in 1899,

Pierre-Simon Laplace Pierre-Simon, marquis de Laplace (; ; 23 March 1749 – 5 March 1827) was a French scholar and polymath whose work was important to the development of engineering, mathematics, statistics, physics, astronomy, and philosophy. He summarized ...

in 1814, and

Thomas Jefferson Thomas Jefferson (April 13, 1743 – July 4, 1826) was an American statesman, diplomat, lawyer, architect, philosopher, and Founding Father who served as the third president of the United States from 1801 to 1809. He was previously the natio ...

in 1808. The formulation "Extraordinary claims require extraordinary proof" was used just two years prior to Sagan, by sociologist

Marcello Truzzi Marcello Truzzi (September 6, 1935 – February 2, 2003) was a professor of sociology at New College of Florida and later at Eastern Michigan University, founding co-chairman of the Committee for the Scientific Investigation of Claims of the P ...

, in 1978.

Application

The Sagan standard, according to Tressoldi (2011), "is at the heart of the

scientific method The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...

, and a model for critical thinking, rational thought and

skepticism Skepticism, also spelled scepticism, is a questioning attitude or doubt toward knowledge claims that are seen as mere belief or dogma. For example, if a person is skeptical about claims made by their government about an ongoing war then the p ...

everywhere". ECREE is related to Occam's razor in the sense that according to such 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 ...

, simpler explanations are preferred to more complicated ones. Only in situations where extraordinary evidence exists would an extraordinary claim be the simplest explanation. A routinized form of this appears in

hypothesis testing A statistical hypothesis test is a method of statistical inference used to decide whether the data at hand sufficiently support a particular hypothesis. Hypothesis testing allows us to make probabilistic statements about population parameters. ...

where the hypothesis that there is no evidence for the proposed phenomenon, what is known as the "

null hypothesis In scientific research, the null hypothesis (often denoted ''H''0) is the claim that no difference or relationship exists between two sets of data or variables being analyzed. The null hypothesis is that any experimentally observed difference is d ...

", is preferred. The formal argument involves assigning a stronger

Bayesian prior In Bayesian probability, Bayesian statistical inference, a prior probability distribution, often simply called the prior, of an uncertain quantity is the probability distribution that would express one's beliefs about this quantity before some e ...

to the acceptance of the null hypothesis as opposed to its rejection. There are no concrete parameters as to what constitutes "extraordinary claims", which raises the issue of whether the standard is subjective. According to Tressoldi this problem is less apparent in clinical medicine and psychology where statistical results can establish the

strength of evidence In biostatistics, Strength of evidence is the strength of a conducted study that can be assessed in health care interventions, e.g. to identify effective health care programs and evaluate the quality of the research in health care. It can be graded ...

. Some would argue that evidence cannot be extraordinary. The definition of evidence, points to the available body of facts or information. Extraordinary claims require extraordinary scrutiny.

History

The aphorism was made popular by astronomer Carl Sagan who used it in the 1980 television show ''

'' in reference to claims about aliens visiting Earth. Sagan made similar statements in a 1977 interview in ''

The Washington Post ''The Washington Post'' (also known as the ''Post'' and, informally, ''WaPo'') is an American daily newspaper published in Washington, D.C. It is the most widely circulated newspaper within the Washington metropolitan area and has a large nati ...

'', and his 1979 book ''

Broca's Brain ''Broca's Brain: Reflections on the Romance of Science'' is a 1979 book by the astrophysicist Carl Sagan. Its chapters were originally articles published between 1974 and 1979 in various magazines, including ''The Atlantic Monthly'', ''The New R ...

'';

did likewise in '' Parapsychology Review'' in 1975 and ''Zetetic Scholar'' in 1978. Two 1978 articles, one in '' U.S. News & World Report'' and another by Koneru Ramakrishna Rao in the '' Journal of Parapsychology'' both quote physicist

Philip Abelson Philip, also Phillip, is a male given name, derived from the Greek (''Philippos'', lit. "horse-loving" or "fond of horses"), from a compound of (''philos'', "dear", "loved", "loving") and (''hippos'', "horse"). Prominent Philips who popularize ...

, then the editor of ''

Science Science is a systematic endeavor that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earli ...

'', using the same phrase. Others had earlier put forward very similar ideas.

Quote Investigator Quote Investigator is a website that fact-checks the reported origins of widely circulated quotes. It was started in 2010 by Gregory F. Sullivan, a former Johns Hopkins University computer scientist who runs the site under the pseudonym Garson O'To ...

cites similar statements from Benjamin Bayly (in 1708), Arthur Ashley Sykes (1740),

Beilby Porteus Beilby Porteus (or Porteous; 8 May 1731 – 13 May 1809), successively Bishop of Chester and of London, was a Church of England reformer and a leading abolitionist in England. He was the first Anglican in a position of authority to seriously c ...

(1800),

Elihu Palmer Elihu Palmer (1764 – April 7, 1806) was an author and advocate of deism in the early days of the United States. Life Elihu Palmer was born in Canterbury, Connecticut in 1764. He studied to be a Presbyterian minister at Dartmouth College, where ...

(1804), and William Craig Brownlee (1824), all of whom used it in the context of the extraordinary claims of Christian theology and the putative extraordinary evidence supplied by the

Bible The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts ...

. Quote Investigator also cites

in essays (1810 and 1814) on the

stability of the Solar System The stability of the Solar System is a subject of much inquiry in astronomy. Though the planets have been stable when historically observed, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ...

, and

Joseph Rinn Joseph Francis Rinn (1868–1952) was an American magician and skeptic of paranormal phenomena. Career Rinn grew up in New York City. He coached Harry Houdini as a teenager in running at the Pastime Athletic Club. He remained a friend to Houdin ...

(1906), a

skeptic Skepticism, also spelled scepticism, is a questioning attitude or doubt toward knowledge claims that are seen as mere belief or dogma. For example, if a person is skeptical about claims made by their government about an ongoing war then the ...

of the

paranormal Paranormal events are purported phenomena described in popular culture, folk, and other non-scientific bodies of knowledge, whose existence within these contexts is described as being beyond the scope of normal scientific understanding. Not ...

in an 1808 letter expresses contemporary skepticism of meteorites thus: "A thousand phenomena present themselves daily which we cannot explain, but where facts are suggested, bearing no analogy with the laws of nature as yet known to us, their verity needs proofs proportioned to their difficulty." Letter to Daniel Salmon on 15 February 1808 discussing the nature and origin of meteorites
U.S. Library of Congress image

References

{{Carl Sagan Adages Carl Sagan Epistemology

Application

History

See also

References