ABSTRACT
There are forms of reasoning, e.g., reasoning with defaults, whose formalization is convenient for applications to Artificial Intelligence, although strictly speaking they ought to be regarded as fallacious and would indeed lead to fallacy if their range of application wasn’t clearly defined. The “user manual” for such logics (implicitly or explicitly) contains a translation into the syntax and the semantics of ordinary propositional or first-order theories. In this way, “default logics” are shown to be no threat to the “unity of logic”.
