Dialogical logic

Dialogical logic (German: dialogische Logik, also known as the logic of dialogues) is a pragmatic approach to the semantics of logic developed in the 1950s by Paul Lorenzen and Kuno Lorenz. It models logical reasoning as a dialogue game between two participants—a "Proponent" who asserts and defends a thesis and an "Opponent" who challenges it—using concepts from game theory such as "winning a play" and "winning strategy." In this framework, a formula is considered logically valid if the Proponent has a winning strategy for its defense against all possible challenges.

Though dialogical logic was among the first approaches to logical semantics using game-theoretical concepts, it should be distinguished from broader concept of game semantics. While both share game-theoretical foundations, they differ in philosophical background and technical development. Dialogical logic emphasizes the normative practice of reasoning and argumentation, drawing inspiration from constructivist philosophy, whereas other game-semantic approaches like Jaakko Hintikka's game-theoretical semantics (GTS) have different theoretical motivations and formal implementations.

Originally focused on providing alternative semantics for classical logic and intuitionistic logic, dialogical logic has evolved into a general framework for studying meaning, knowledge, and inference in interactiv e contexts. Recent developments include the study of cooperative dialogues beyond strictly adversarial games, and dialogues deploying a fully interpreted language (referred to as "dialogues with content"), extending its applications to philosophy of language, epistemology, and argumentation theory.