The Sagan Standard: Extraordinary Claims Require Extraordinary Evidence - Effectiviology
The Concept Of Extraordinary Claims
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 threshold on the ordinary-extraordinary spectrum that a certain claim needs to cross before it’s considered extraordinary, it’s generally preferable to focus on how extraordinary a claim is instead, and to expect a stand of proof that matches that degree of extraordinariness.
A claim should generally not be viewed as extraordinary simply because it’s novel, but rather because it contradicts existing evidence.
Using double standards intentionally involves an informed, conscious decision to do so and happens mostly when a person thinks that the double standards could help them achieve some goal (helping someone that they favor, hurting someone that they dislike etc.)
Using double standards unintentionally means a person fails to acknowledge the double standard, and is generally driven by some motivation, often emotional in nature.
"We should ignore the theory of evolution because the dictionary says that a theory is just an opinion that you have about something you can't prove."
The person using this fallacy is basing their statement on a specific definition of the word "theory" while ignoring alternative definitions that will better capture the meaning of the term as it's used in a scientific context.
Not every use of a definition is necessarily fallacious. If the definition is properly justified and is selected in a properly justified way, it is generally not fallacious. However, it is fallacious when at least one of the following conditions are true:
There is no valid reason for using the definition.
The definition was cherry-picked out of a range of possible definitions.