Reasoning about the Appropriateness of Proponents for Arguments

Formal approaches to modelling argumentation provide ways to present arguments and counterarguments, and to evaluate which arguments are, in a formal sense, warranted. While these proposals allow for evaluating object-level arguments and counterarguments, they do not give sufficient consideration to evaluating the proponents of the arguments. Yet in everyday life we consider both the contents of an argument and its proponent. So if we do not trust a proponent, we may choose to not trust their arguments. Or if we are faced with an argument that we do not have the expertise to assess (for example when deciding whether to agree to having a particular surgical operation), we tend to agree to an argument by someone who is an expert. In general, we see that for each argument, we need to determine the appropriateness of the proponent for it. So for an argument about our health, our doctor is normally an appropriate proponent, but for an argument about our investments, our doctor is normally not an appropriate proponent. In this way, a celebrity is rarely an appropriate proponent for an argument, and a liar is not necessarily an inappropriate proponent for an argument. In this paper, we provide a logic-based framework for evaluating arguments in terms of the appropriateness of the proponents.