Inference, Circularity, and Begging the Question

I develop a syntactic concept of circularity, which I call propositional circularity. With respect to a given use of an argument advanced as a statement of inference for the benefit of a reasoner R, if the direct and indirect premises R would have to accept in order to accept the conclusion includes the conclusion, then the collection of premises is propositionally circular. The argument fails to display a type of inference that R can perform. Appealing to propositional circularity, I articulate a sufficient condition for a use of an argument to beg the question, highlighting why question-begging is a defect.