Sagan’s extraordinary-claims rule fails because what seems extraordinary is subjective

Evidence

The American astronomer Carl Sagan is credited with the sentence: “Extraordinary claims require extraordinary evidence.” According to this, the onus of proof would be on the person who makes the more extraordinary claim that deviates from the scientific consensus. Why this should be so, however, is not obvious to everyone. For some homeopaths, the efficacy of modern medicines, which is comprehensible on the level of individual chemical interactions, may seem more extraordinary than the scientifically untenable, but in a magical sense plausible, similarity principle of their own teaching. As an argument in a discussion with believers, then, Sagan’s claim may be met with the accusation that double standards are being applied. — Holm Gero Hümmler, Ulrike Schiesser, Fact and Prejudice, 764

Categorization

• CANDY: The idea that a homeopath could see modern pharmacology as more extraordinary than their own magical similarity principle is a wry, tweetable inversion.