This is a collection of new investigations and discoveries on the theory of opposition (square, hexagon, octagon, polyhedra of opposition) by the best specialists from all over the world. 

The papers range from historical considerations to new mathematical developments of the theory of opposition including applications to theology, theory of argumentation and metalogic.

Part I  Introduction.- Part II  Historical Perspectives on the Square.- Part III  Reinterpretations of the Square.- Part IV  Philosophical Perspectives on the Square.- Part V   Theoretical Investigations on the Square.- Part VI  Expansions and Variations of the Square.- Part VII  Applications of the Square.