Abstract

This book is an attempt to relate the operative and constructive formulation of symbolic logic carried out by Lorenzen—and to a lesser degree Kolmogorov and Markov—to both Wittgenstein's philosophy of logic as set forth in the Tractatus and later modified in the Investigations, and to Brouwer's critique of classical logic, especially the principles of excluded middle. The first chapter contains an exposition of Wittgenstein's critical analysis of the "mythical" views of Russell and Frege; and it develops his own "operative" theory of elementary logic. The second chapter concerns the relations of the theories of Brouwer and Wittgenstein; the last section is a detailed survey of chiefly Lorenzen's operative logic in which the presentation of a dialogue-like interpretation of logic is exhaustively analyzed: the notion of a "winning strategy" in such a two-person dialogue is set forth, the technique is extended to classical logic from its original, weaker operational form, and its relations to Gentzen's Sequenzen-kalkül is discussed. The work was the author's Habilitationsschrift at Innsbruck University.—P. J. M.