Book 5, Chapter 7, Footnote #02
A later restriction made by Whately
In his later editions, Archbishop Whately confines the name of Petitio Principii ``to those cases in which one of the premises either is manifestly the same in sense with the conclusion, or is actually proved from it, or is such as the persons you are addressing are not likely to know, or to admit, except as an inference from the conclusion: as, e. g. if any one should infer the authenticity of a certain history from its recording such and such facts, the reality of which rests on the evidence of that history.''