Based on the Sagan standard, if someone claims that they came across a unicorn during they commute, they would be expected to brig stronger evidence in order to verify that claim than if they claimed that they came across a horse.

• Instead of viewing claims as either ordinary or extraordinary, it’s better to view them as ranging between these two ends of the spectrum, based on how likely they are given everything that is known on the subject.
• It can be difficult to define the exact th...

The Sagan standard is related to astronomer Carl Sagan, who stated that “extraordinary claims require extraordinary evidence” (a dictum abbreviated as ECREE).

There is no clear separation between what is ‘ordinary’ evidence and what is ‘extraordinary’ evidence; the answer is in most cases subjective, though it should nevertheless be based on sound reasoning.

The more unlikely a claim is, the more supporting substantial the evidence that you should require before accepting it as true.