As the poster for the Centre for Inquiry notes, extraordinary claims require extraordinary evidence. It’s a popular catchphrase for the skeptical movement, but should be an intellectual policy for everyone.
Regardless of what is being claimed, it requires evidence at the same level of the claim.
Anecdote is not evidence, please note, especially personal anecdote even with the corroboration of other witnesses. People often “see” what they choose to see, and interpret events and objects according to preconceived ideas. Seeing UFOs instead of ordinary aircraft, or chemtrails instead of mundane contrails are examples of this. Evidence is something concrete; a body of facts, not simply interpretation or disingenuous claim.
The Centre lists many claims as the poster indicates – a list that continues to grow – along with a brief introduction to each: claims, evidence and conclusion. Some like leprechauns, the Easter Bunny, tooth fairy, dragons and Xenu seem pretty obviously mythological or (like Xenu) totally fabricated. Others will certainly raise an argument among some religious believers or the superstitious – angels, magic, Heaven, hell, the afterlife and similar religious topics included (it does not yet list Santa Claus, but I expect it will come)..
As RationalWiki puts it,
Extraordinary claims require extraordinary evidence was a phrase made popular by Carl Sagan. It is central to scientific method, and a key issue for critical thinking, rational thought and skepticism everywhere.
The actual phrase was coined by sociologist Marcello Truzzi, but it has been around in other forms for several centuries. In his 1748 work, An Enquiry concerning Human Understanding (chap. 10.4.), David Hume wrote:
In our reasonings concerning matter of fact, there are all imaginable degrees of assurance, from the highest certainty to the lowest species of moral evidence. A wise man, therefore, proportions his belief to the evidence… No testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous than the fact which it endeavors to establish.
Simply because a lot of people believe in something, or accept it as factual doesn’t mean it is true. In a letter to Adam Smith, Hume wrote:
Nothing indeed can be a stronger presumption of falsehood than the approbation of the multitude…
The 19th century French scholar, Pierre-Simon Laplace, wrote in an essay in 1812:
The weight of evidence for an extraordinary claim must be proportioned to its strangeness.
Later, in an essay critical of Christianity that remained unpublished until 2005, Laplace wrote,
…first and most infallible of principles … to reject miraculous facts as untrue
The RationalWiki page also notes that one has to weigh,
…the improbability of the evidence presented in proportion to the improbability of the claim being made.
As a general principle in reason and logic, the statement that “extraordinary claims require extraordinary evidence” is true, regardless of whether the claim is one of divine intervention, anti-vaccination dangers, or the misanthropic mewlings of local bloggers. But it should be true of all claims, regardless of the degree of improbability of their claim.
Evidence – not anecdote, not rumour, not gossip – should be presented – although it seldom is in the examples above – so it can be properly weighed and analysed, and held up to the light of intense scrutiny of logic and reason for traces of validity.
When the Buddha visited the Kalamas more than 2,500 years ago, they approached him for guidance on how to assess the competing and often confrontational claims made by competing monks, telling Gautama that these monks:
…expound and explain only their own doctrines; the doctrines of others they despise, revile, and pull to pieces. Venerable sir, there is doubt, there is uncertainty in us concerning them. Which of these reverend monks and brahmans spoke the truth and which falsehood?
Sound like the anti-vaccination movement? Stephen Harper’s anti-Trudeau ads? The ravings of local bloggers? How little has changed in two-and-a-half millennia.
The Buddha warned his audience not to be taken in by their claims, nor by mere gossip, dogma, bias, tradition or even by popular acceptance of a belief. Examine the evidence yourself, he told them. Discover the truth behind the claims, and reject those claims if they fail to pass muster. Use your head.
As Soma Thera wrote of the Kalama Sutra that it:
…sets forth the principles that should be followed by a seeker of truth, and which contains a standard things are judged by…
You’ll find that, when so subjected, most of these claims usually prove to be little more than, in the words of Conrad Black, “diaphanous piffle.” They evaporate in the strong light of reason and fact (at which point the claimants often resort to name calling and vulgarity in response to being exposed).
Use your own facility for critical thinking when you are confronted by anything that strikes you as an ‘extraordinary claim’ – and subject those claims to scrutiny. Do not simply accept a claim without demanding that you see for yourself the evidence accompany it. And ask to see ALL of it, not just the edited and selected bits that support a particular bias.