Reason-Giving Uses of Arguments, Formally Valid Arguments, and Demonstrative Arguments

Abstract

Abstract This chapter reviews the distinction between deductive and inductive arguments, distinguishing between demonstrative and ampliative arguments. Also, and formally valid and demonstrative arguments are distinguished. The formal validity of an argument is germane to whether a reason-giving use of it is good only because formally valid arguments are demonstrative arguments. Some (classically) formally valid arguments do not correspond to reflective inferences and so cannot be successfully used to advance their premises as reasons for their conclusions. This matters to whether a formal logic such as classical logic is adequate for judging reflective inferences. Three norms, pragmatic, doxastic, and dialectical, guide reason-giving uses of arguments. These norms are used to explain when a deductive argument that advance reasons for believing its conclusion should be demonstrative, and when an argument’s being demonstrative matters to the legitimacy of the corresponding reflective inference.