Jan Dejnožka, The Concept of Relevance and the Logic Diagram Tradition

This book offers a new interpretation of relevance in logic. It does so by reuniting two areas of logical research that have been historically unrelated: diagrammatic logic and relevance logic. Dejnoˇzka offers one main argument for their reunifica- tion: (1) If the premises of an argument contain its conclusion, the argument is relevantly valid. (2) If the diagram of the premises of an argument is ipso facto the diagram of the conclusion, then the premises contain the conclusion. (3) Ar- guments which according to standard relevantists are invalid can be represented in diagrams so as to show that the premises contain the conclusion. (4) Therefore, such arguments are relevantly valid.