The pure calculus of entailment

Abstract

The “implicational paradoxes” are treated by most contemporary logicians somewhat as follows:“The two-valued prepositional calculus sanctions as valid many of the obvious and satisfactory inferences which we recognize intuitively as valid, such as(A→.B→C)→.A→B→.A→C,2andA→B→.B→C→.A→C;it consequently suggests itself as a candidate for a formal analysis of implication.