Abstract
The evaluation of arguments and argumentation is best understood epistemologically. Epistemic circularity is not formally defective but it may be epistemologically objectionable. Sorenson's doubts about the syntactic approach to circularity are endorsed with qualifications. One explanation of an argument's goodness is its ability to produce justified belief in its conclusion by means of justified belief in its premises, but matters are not so simple for interpersonal argumentation. Even when an argument's premises and conclusion are justified for a speaker, this justifiedness may not be transmissible to every hearer. Still, an epistemic approaeh is instructive. Arguing in enthymemes can be legitimate, e.g., because enthymemes can help produce justified persuasion in an audience that supplies the missing premises