Abstract

And similar inductive logic, deductive logic problems facing the reasonable defense of deductive logic is an important issue in the philosophy of logic one can not do with the interpretation of inductive logic to defend, using deductive logic of justifying the interpretation will lead to failure. Previous interpretation of the defense, in addition to leading to circular reasoning, but also another reason for the failure to object in the meta-language in justifying the theory of language, which would lead to endless back, and ultimately impossible to escape the scope of the language. Deductive logic reasoning is that people invented tools, but also a strict accordance with the rules of the game, people can not make it ontological or epistemological defense. Like inductive logic, deductive logic also faces the problem of rationality. The justification of deductive logic is one of the most important problems in the philosophy of logic: deduction can neither be justified by inductive logic nor deductive logic. And if we justify of object- language in meta-language, it would result in an unlimited regression which is forever hopeless to get out of language. Deductive logic is a tool invented for inference, yet it is also a game played rigorously according to rules. It cannot be justified by any ontology or epistemology