[Revised entry by James Garson on January 23, 2023.
Changes to: Main text, Bibliography]
A modal is an expression (like ‘necessarily’ or ‘possibly’) that is used to qualify the truth of a judgement. Modal logic is, strictly speaking, the study of the deductive behavior of the expressions ‘it is necessary that’ and ‘it is possible that’. However, the term ‘modal logic’ may be used more broadly for a family of related systems. These include logics for belief, for tense and other temporal expressions, for the deontic (moral) expressions such as…
Originally appeared on Stanford Encyclopedia of Philosophy Read More
