"The phrase "Extraordinary claims require extraordinary evidence" was popularized by Carl Sagan (1934 - 1996), a well-known astronomer and author who hosted a TV series called "Cosmos," published hundreds of scientific articles, and was professor of astronomy at Cornell University in New York. The statement is self explanatory; if someone makes an extraordinary claim, there better be extraordinary evidence to back it up. If, for example, someone made the claim that an alien race has made contact with earth, we would need sufficient evidence to verify the claim, such as an alien space craft, or an actual alien. The extraordinary claim would need extraordinary evidence."
Source: http://carm.org/extraordinary-claims-req...y-evidence
Source: http://carm.org/extraordinary-claims-req...y-evidence