Quote by Carl Sagan: “Extraordinary claims require extraordinary evidence.”

This principle is a cornerstone of scientific skepticism, demanding higher standards of proof for assertions that challenge established understanding. It teaches us to be critical thinkers, ensuring that beliefs are proportional to the quality and quantity of supporting evidence, especially for unusual ideas.

Though the concept has older roots, Sagan popularized this "Sagan Standard" in "Cosmos" and other works, particularly in his critiques of pseudoscience and claims of UFOs, urging rational thought amidst growing public fascination with the unexplained.

American astronomer, planetary scientist, cosmologist, astrophysicist, astrobiologist, author, and science communicator. His best known scientific contribution is research on extraterrestrial life, including experimental demonstration of the production of amino acids from basic chemicals by radiation.