Contingency Logics and Propositional Quantification
Claudio Pizzi · LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) · 1999
The problem of defining modal operators using contingency as a primitive is discussed by assuming what Lewis and Langford call "Existence Postulate", an axiom which is formulated in the framwork of a modal language with propositional quantifiers. It is shown that the minimal contingency logic K Δ extended with the contingential counterpart of Existence Postulate is definitionally equivalent to the deontic logic KD extended with propositional quantifiers.