The theory of the square of opposition has been studied for over 2, 000 years and has seen a resurgence in new theories and research since the second half of the twentieth century. This volume collects papers presented at the Sixth World Congress on the Square of Opposition, held in Crete in 2018, developing an interdisciplinary exploration of the theory. Chapter authors explore subjects such as Aristotle¿s ontological square, logical oppositions in Avicennäs hypothetical logic, and the power of the square of opposition to solve theological problems regarding predestination and theodicy. Other topics covered include:Hegel¿s opposition to diagrams
De Morgan¿s unpublished octagon of opposition
turnstile figures of opposition
institutional model-theoretic treatment of oppositions
Lacan¿s four formulas of sexuation
the theory of oppositional poly-simplexes

The Exoteric Square of Opposition will appeal to pure logicians, historians of logic, semioticians, philosophers, theologians, mathematicians, and psychoanalysts.