Kazimierz Ajdukiewicz

Works

• 1934Language and Meaning

  Meaning is fixed by the rules of a language; since different languages yield different, untranslatable pictures of the world, the choice of language decides which world picture we have – radical conventionalism.

• 1935Syntactic Connexion

  Assigns each expression a category and shows by calculation whether a sentence is well formed – the foundation of categorial grammar.

Position

Ajdukiewicz is a central figure of the Lwów–Warsaw School. In “Language and Meaning” and “The World-Picture and the Conceptual Apparatus” (both 1934) he argued that the meaning of an expression is fixed by rules – axiomatic, deductive and empirical – that speakers must accept. Since closed languages with different rules cannot be translated into one another, which judgements we accept depends on the conceptual apparatus we choose. This “radical conventionalism” went beyond Henri Poincaré and Édouard Le Roy; Ajdukiewicz himself gave it up in the late 1930s, conceding that real languages are neither closed nor connected in his sense, and turned to a semantic epistemology and later to a radical empiricism. His 1935 paper on syntactic connexion, building on Husserl’s categories of meaning and Leśniewski’s semantic categories, assigned every expression a category and gave a procedure for testing whether a string is well formed; Yehoshua Bar-Hillel and Joachim Lambek developed it in the 1950s into categorial grammar, a basis of later formal semantics. His view of meaning as acceptance according to rules is discussed today as an early form of inferential role semantics. Critics have objected that such rules are hard to identify in natural languages.

Life & context

Kazimierz Ajdukiewicz was born on 12 December 1890 in Tarnopol in Austrian Galicia (today Ternopil, Ukraine). He studied philosophy, mathematics and physics in Lwów, where Kazimierz Twardowski supervised his doctorate on Kant’s theory of space (1912); he later married Twardowski’s daughter Maria. In 1913 he spent a semester in Göttingen with Edmund Husserl and David Hilbert. During the First World War he served in the Austrian army. After his habilitation in Warsaw (1921) he taught there and in the 1920s returned to Lwów as professor. In 1934–35 he published his main papers on meaning and on syntactic connexion in “Erkenntnis” and “Studia Philosophica”; he also wrote textbooks of logic for schools. He lived through the Second World War in Lwów under Soviet and then German occupation. After 1945 he moved to Poznań, where he was rector of the university from 1948 to 1952, and in 1955 to Warsaw. In 1953 he founded the journal “Studia Logica”. He died in Warsaw on 12 April 1963.

Further main works

• The Main Directions of Philosophy (Główne kierunki filozofii, 1923)
• The World-Picture and the Conceptual Apparatus (Das Weltbild und die Begriffsapparatur, 1934)
• Problems and Theories of Philosophy (Zagadnienia i kierunki filozofii, 1949)
• Pragmatic Logic (Logika pragmatyczna, 1965)