Begging the question

In classical rhetoric and logic, begging the question or assuming the conclusion (Latin: petitio principii) is an informal fallacy that occurs when an argument's premises assume the truth of the conclusion. Historically, begging the question refers to a fault in a dialectical argument in which the speaker assumes some premise that has not been demonstrated to be true. In modern philosophical usage, it has come to refer to an argument in which the premises assume the conclusion without supporting it. This makes it an example of circular reasoning. An example is: “Wool sweaters are better than nylon jackets as fall attire because wool sweaters have higher wool content". The claim here is that wool sweaters are better than nylon jackets as fall attire. But the claim's justification begs the question, because it presupposes that wool is better than nylon. An essentialist analysis of this claim observes that anything made of wool intrinsically has more "wool content" than anything not made of wool, giving the claim weak explanatory power for wool's superiority to nylon. In modern times, "beg the question" has taken on the common meaning of "raises the question", a usage distinct from the study of logic. This usage is criticized for diluting the original meaning of the phrase.