Abstract

Logical argument is one of the strongest kinds of argument, for it can be applied to any domain. In the domain of law, however, many arguments which are not formally valid are still admissible. We consider these arguments to be special-valid. On the other hand, Arguments which have false premises and false conclusions, or false premises and true conclusions are unacceptable in law because in law nothing can follow from false premises. The aim of a legal argument is to persuade audiences to accept the claim, and nobody can accept an invalid argument rationally. In this sense, the validity of legal argument is the same as the soundness of logical argument. Moreover, the premises of legal arguments such as factual propositions are not the facts themselves but legal facts reconstructed by evidence. This paper distinguishes the logical content from the material content of an argument formulates the special-validity system of argument in the framework of law from two perspectives: the internal structure and external structure.