4 articles
General
Counterpart theory
Counterpart theory is David Lewis's 1968 semantic framework for modality: an individual exists in only one possible world, and its modal properties are evaluated through counterparts.
General
Intension
Intension, also called intensionality, is the sense or internal content of a term, as opposed to its extension, the range of things the term applies to.
General
Quantified modal logic
Quantified modal logic (QML) combines a propositional modal logic with first-order quantifiers; the Barcan Formula is valid under constant domains but fails under the varying domains Kripke introduced in 1963.
General
Rigid designator
A rigid designator is an expression, such as a proper name, that names the same object in every possible world, a concept introduced by Saul Kripke.