In this paper I propose to continue the analysis of the appeal to authority begun at the last OSSA conference. I proceed by examining the well-documented use of the appeal made by the ancient Roman advocate, Cicero. The fact that Cicero expressed his opinion was expectably sufficient to give his auditors--responsible citizens all--reason to do as he desired. But why? The resolution of this puzzle points to a strong sense in which arguments can be called rhetorical , for the rational (...) force of Cicero's authority depends necessarily on what he says. (shrink)