The German-American philosopher Rudolf Carnap (1891-1970) was the most prominent representative of the school of logical positivism, sometimes called logical empiricism.
Rudolf Carnap was born on May 18, 1891, in Ronsdorf, Germany. From 1910 to 1914 he studied philosophy and science at the universities of Jena and Freiburg. At Jena, Gottlob Frege, the pioneering mathematical logician, directed his thinking. Carnap served as an officer in the Germany army during World War I, later resuming his studies at Jena, where he received his doctorate in 1921. As a student, Carnap came under the influence of Bertrand Russell and his writings on logic and epistemology.
In 1923 Carnap met Hans Reichenbach, with whom he later founded and edited Erkenntnis (1930-1940), the journal of the logical empiricists. Through Reichenbach he met Moritz Schlick, head of the Philosophical Circle at the University of Vienna. In 1926 Carnap became instructor of philosophy there and participated in the Circle. Ludwig Wittgenstein attended meetings of the Circle in 1927, becoming another influence on Carnap's thought.
Carnap won wide recognition among philosophers with the publication of the Logische Aufbau der Welt (Logical Structure of the World) in 1928. He offered a new methodology, which called for the reduction of all knowledge to private, subjective sense-data in order to construct a technical system to embrace all known-objects and to solve philosophical problems. In 1928 Carnap also published Scheinprobleme in der Philosophie (Fictitious Problems in Philosophy). Following Wittgenstein, he sought to show that metaphysical problems are pseudoproblems and that metaphysical sentences are "non-sense."
In 1931 Carnap became professor of natural philosophy at the German university in Prague. In 1933 he married Elizabeth Ina von Stöger.
Carnap's investigations into logic and mathematics came to fruition with the publication of The Logical Syntax of Language (1934). Utilizing the distinction between "metalanguage" and "object language" advanced by Polish logicians, Carnap sought to develop a metalanguage (which he called "logical syntax") to elucidate and formalize the basic terms, formation rules, and transformation rules of object languages—that is, systems of logic and mathematics. He proposed his famous "principle of tolerance," which permits anyone to construct any language he wishes.
Fleeing from Nazism, Carnap went to the United States in December 1935. A few months later he was appointed professor of philosophy at the University of Chicago. In 1941 he became a naturalized citizen. Except for leaves to research or to teach elsewhere, he remained at Chicago until 1952.
At the university Carnap joined Otto Neurath and Charles W. Morris to found and edit the International Encyclopedia of Unified Science. Carnap's contribution to the encyclopedia is entitled Foundations of Logic and Mathematics (1930). This work displays a radical shift in his thinking. Persuaded by Alfred Tarski, Carnap had become convinced that the logical analysis of language extends beyond logical syntax and includes semantics, which deals with the reference of language to objects and contains the concepts of meaning and truth. Thus Carnap initiated a series of studies in semantics: Introduction to Semantics (1942), Formalization of Logic (1943), and Meaning and Necessity (1947).
In 1950 Carnap's massive book, The Logical Foundations of Probability, climaxed his investigations into the logic of empirical knowledge. From 1952 to 1954 Carnap advanced his researches into the logic of science at the Institute for Advanced Study in Princeton. In 1954 he accepted the chair in philosophy at the University of California, Los Angeles, made vacant by the death of Reichenbach. Retiring from teaching in 1961, he continued as a research professor until his death on Sept. 14, 1970, in Santa Monica, Calif.
P. A. Schillp, ed., The Philosophy of Rudolf Carnap (1963), containing Carnap's intellectual autobiography, is basic. Carnap's views receive some attention in Julian Weinberg, An Examination of Logical Positivism (1936); Victor Kraft, The Vienna Circle (1950); and Joergen Joergensens, The Development of Logical Positivism (1951). See also Wolfgang Stegmuller, Die Wahrheitsidee und die Idee der Semantik (1957); B. H. Kazemeir and D. Vuijsje, eds., Logic and Language (1962); Alan Hausman and Fred Wilson, Carnap and Goodman (1967); and Arne Naess, Four Modern Philosophers. □
Philosopher; b. Ronsdorf, Germany, 1891; d. Los Angeles, Calif., Sept. 14, 1970. Carnap was the most prominent representative of logical empiricism (also called logical positivism and neopositivism). He was privat-dozent at Vienna from 1926 to 1931, professor at Prague from 1931 to 1936, at Chicago from 1936 to 1952, and at Los Angeles from 1954 to 1961. His principal contributions were in the areas of meaning, logic, philosophy of science, and philosophy of probability.
In the theory of meaning, his work centered on the verification theory of meaning, the view that the meaning of sentences consists in the conditions of their verification. Carnap's initial formulation identified verifiability with translatability into phenomenalist language (not, however, using visually oriented "sense-data" as primitive) and the task of philosophy with the "logical construction" of all human knowledge. As a by-product of this analysis, he deduced the meaninglessness of metaphysics as a result of its untranslatability.
Convinced in the early 1930s by his research and by discussions with his colleagues of the Vienna Circle (of which he was a leading member) of the untenability of his original position, Carnap rejected phenomenalism for physicalism, reinterpreting the empirical basis of protocol statements concerning physical observations and measurements and rejoining translatability—being able to eliminate theoretical terms—in favor of testability— being able to test derived observations—as the criterion of meaning. This he liberalized further in the 1950s, finally arriving at the requirement that a sentence is meaningful if it really adds to the observation statements derivable from a theory. Carnap nevertheless felt that the more liberal criterion ruled out metaphysics while retaining established science.
In logic, Carnap developed logical syntax, which he hoped could be used to establish his philosophical view but whose influence has proved greater in pure logical theory. He also contributed substantially to formal semantic theory. More important yet was his work on modal logic, which introduced the semantic treatment later developed by Kripke.
Much of the work of his last decades was devoted to establishing the possibility of constructing the logical concept of probability by semantic concepts. This work, successful technically, failed to have the philosophical impact he anticipated because of his inability to establish convincingly a unique probability concept.
Carnap's intellectual honesty and his demonstration of the power of modern logic has had an overwhelming influence on a whole generation of philosophers.
Bibliography: Carnap's most influential studies: Die logische Syntax der Sprache (Vienna 1934), tr. The Logical Syntax of Language (London 1937). "Testability and Meaning," Philosophy of Science 3 (1936) 419–471, 4 (1937) 1–40. Meaning and Necessity (Chicago 1947). Logical Foundations of Probability (Chicago 1950). "The Methodological Character of Theoretical Concepts," in feigl et al., Minnesota Studies in the Philosophy of Science 1 (Minneapolis 1956) 38–76. Philosophical Foundations of Physics (New York 1966). Other important works: Der Raum, Logical Construction of the World, Pseudo-Problems in Philosophy, Philosophy and Logical Syntax, Introduction to Semantics and Introduction to Symbolic Logic. Significant books on Carnap: krauth, Die Philosophie Carnaps (Vienna 1970). p. a. schilpp, ed., The Philosophy of Rudolf Carnap (La Salle, Ill. 1963). barone, Filosofia 4.353–392. caponigri, Les grandes courants de la pensée mondiale contemporaine, ser. 3, 1.267–295.
[n. m. martin]