before 'logical probability' (in contradistinction to 'relative' or 'conditional' logical probability); appendices ii, iv, and logically less probable predictions of this kind have been successful, then it is not, as a rule, their success that we are inclined to doubt so much as their alleged logical improbability: since we tend to believe that such prophecies are non corroborable, we also tend to argue in such cases from their low degree of corroborability to their low degree of testability.