Popularized by astronomer Carl Sagan, the actual source of the quote I used to title this post may be from Marcello Truzzi, a co-founder of the debunking group called CISCOP. The concept, however, goes back to people such as the French astronomer Pierre-Simon, marquis de Laplace —usually just called "Laplace"— (""The weight of evidence for an extraordinary claim must be proportioned to its strangeness") or even Scottish philosopher David Hume ("A wise man, therefore, proportions his belief to the evidence"). It seems so reasonable. The question, however, is should we accept it as valid? The people at SCEPCOP point out that no matter how reasonable it seems, the debunkers or