First I want to say that I am not looking for a debate I just want some clarification. Sometimes when people discuss things like life after death or god some people say "Extraordinary claims require extraordinary evidence". How is this scientific? Is there an objective way to determine if a claim is extraordinary and is there an objective way to determine if a piece of evidence is extraordinary? As far as I know the answer is no. With the information I have at hand I have no choice but to conclude that what counts as an extraordinary claim or evidence is completely subjective and therefore not scientific.

So I must ask is the phrase "Extraordinary claims require extraordinary evidence" a valid scientific argument? Once again I am not looking to debate I just want to know if I am taking the phrase in the right context.