The aim of this paper is to apply properties of the double dual endofunctor on the category of bounded distributive lattices and some extensions thereof to obtain completeness of certain non-classical propositional logics in a unified way. In particular, we obtain completeness theorems for Moisil calculus, n-valued Łukasiewicz calculus and Nelson calculus. Furthermore we show some conservativeness results by these methods.
We consider the class of pointed varieties of algebras having a lattice term reduct and we show that each such variety gives rise in a natural way, and according to a regular pattern, to at least three interesting logics. Although the mentioned class includes several logically and algebraically significant examples (e.g. Boolean algebras, MV algebras, Boolean algebras with operators, residuated lattices and their subvarieties, algebras from quantum logic or from depth relevant logic), we consider here in greater detail Abelian ℓ-groups, (...) where such logics respectively correspond to: i) Meyer and Slaney’s Abelian logic ; ii) Galli et al.’s logic of equilibrium ; iii) a new logic of “preservation of truth degrees”. (shrink)
In 1956 W. B. Gallie advanced the thesis that certain political concepts, such as that of social justice, are .1 Since then, a considerable literature on the subject has developed, some of it in support of the thesis, some of it in opposition to it.2 W. E. Connolly is a leading supporter of it, and John Gray is a leading opponent of it. However, Connolly's advocacy of it in the second edition of his book is significantly more moderate than that (...) in the first (1974) edition of it. (shrink)