12th January 2012

Sagan’s Standard

Carl Sagan

Extraordinary claims require extraordinary proof.

Cornell astronomer Carl Sagan was credited with originating this high standard of proof by William Schopf at the news conference at which NASA announced the discovery of microfossils, of apparently primitive organic forms, in a meteorite that had come to Earth from Mars (New York Times, August 8th 1996). Schopf, a paleobiologist at the University of California at Los Angeles, had doubts about the analysis of the meteorite, as indicated by his appeal to Sagan’s Standard. Before accepting the claim of life on Mars, he wanted to see more evidence, including the presence of a population of organisms with traces of cell walls and cell divisions showing their life cycle.

Sagan’s Standard is a distillation in effect of Scottish philosopher David Hume’s rule for judging miracles: “No testimony is sufficient to establish a miracle unless the testimony be of such kind that its falsehood would be more miraculous than the fact which it endeavors to establish” (An Enquiry Concerning Human Understanding ‘Of Miracles’ 1748).

Discussion of Sagan’s Standard

Post your comment here

Submit a new law     (guidelines)


I agree to the submission terms *

Subscribe via email