ABSTRACT
An inferential schema may be thought of as a claim that given as premisses certain valid propositional schemata, a further propositional schema is also valid. If the inferential schema is valid, then the claim is a good one—the schema is a guarantee of the validity of the conclusion, given the validity of the premisses. An axiomatic system or axiomatization of the propositional calculus consists essentially of: a set of wffs of Propositional Calculus (PC), called the axioms of the system; a set of rules of inference which license operations on wffs of PC and the set of all wffs of PC which can be obtained from the axioms by use of the rules of inference; these new wffs are called theorems of the system, or consequences of the axioms under the stated rules of inference.
