Modal logic, an extension of classical logic, investigates the modes of truth such as necessity and possibility. Its development has been closely intertwined with advances in proof theory, a field ...

Tradition states that above the entrance to Plato’s Academy were inscribed the words, “Let no one ignorant of geometry enter here.” A student in the modal logic interim course studies how subjunctives ...

The Journal of Philosophical Logic provides a forum for work at the crossroads of philosophy and logic, old and new, with contributions ranging from conceptual to technical. Accordingly, the Journal ...

Studia Logica: An International Journal for Symbolic Logic, Vol. 101, No. 5 (October 2013), pp. 1061-1072 (12 pages) Every truth-functional three-valued propositional logic can be conservatively ...

In 1959, a paper appeared in The Journal of Symbolic Logic, with the unimpressive-sounding title “A Completeness Theorem in Modal Logic.” A completeness theorem is a guarantee that every universal ...