Rudolf Carnap

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Paul Rudolf Carnap (born May 18, 1891 in Ronsdorf , today a district of Wuppertal ; † September 14, 1970 in Santa Monica , California ) was a German philosopher and one of the main exponents of logical empiricism . For Carnap, the task of philosophy was the logical analysis of (scientific) language, where he was one of the first theorists to try the logical works of Gottlob Frege , Bertrand Russell and Alfred North Whitehead forepistemological and philosophy of science to make issues available.


Carnap's birthplace in Wuppertal

Rudolf Carnap was born to deeply religious parents. His father, Johannes S. Carnap, who came from a poor weaver family, had made it to prosper as the owner of a weaving mill. Carnap's mother, Anna Carnap, was the daughter of the pedagogue Friedrich Wilhelm Dörpfeld . Carnap's birthplace, the so-called Villa Carnap , is located in Ronsdorf in the street In der Krim in the immediate vicinity of the Ronsdorf facilities .

After the father's death in 1898, the family first moved to Barmen , now also a district of Wuppertal, where the young Carnap attended the humanistic grammar school. In 1909 the family moved to Jena , where the mother's brother Wilhelm Dörpfeld was honorary professor at the university. Here Carnap obtained his Abitur at the Carolo-Alexandrinum high school .

Carnap then studied mathematics , physics and philosophy in Jena (among others with Gottlob Frege ) and Freiburg from 1910 to 1914 . Here he was involved in the youth movement , especially in the so-called Serakreis around Eugen Diederichs and in the Jena Academic Association . When the First World War broke out , he became a soldier in the German army. After the war, Carnap resumed his philosophy studies and received his doctorate in 1921 with the work The Room with the Neo-Kantian Bruno Bauch . In 1926 he completed his habilitation with his first major work, The Logical Structure of the World, at the University of Vienna , where he then worked as a private lecturer until 1931 and, as a leading member, played a major role in the discussions of the Vienna Circle . He was married to Elisabeth Carnap (called Eli, * 1895). Around 1930 she became the partner of the graphologist and philosopher Broder Christiansen . From 1931 to 1935 Carnap held an extraordinary professorship for natural philosophy at the German University in Prague .

In 1936 he emigrated to the USA through the mediation of Charles W. Morris and Willard Van Orman Quine , where he initially taught at the University of Chicago . In 1941 he became a citizen of the United States. From 1952 to 1954 he was a professor at Princeton University before he accepted an appointment at the University of California, Los Angeles in 1954 , where he taught until his retirement in 1961.

He died in Santa Monica on September 14, 1970.

Carnap learned Esperanto at the age of 14 , attended the World Esperanto Congress in 1908 and practically used this language on a trip to Europe. In his autobiography from 1963 he expresses himself very positively about Esperanto.


Already in his youth he internally distanced himself from the religiosity of his parents and, especially in his academic years, increasingly doubted his belief in a personal God and in the supernatural elements of religious doctrines. His worldview subsequently broke away from the supernatural and initially approached a pantheism in the tradition of Goethe and Spinoza . When he realized that pantheism, at best, is tenable as an emotional-ethical view, but has no scientific basis, he finally arrived at a naturalism , according to which all events are part of nature.


Contrary to the widespread prejudice that Carnap was an apolitical positivist (and thus allegedly favoring political and social reaction), Carnap was politically active throughout his life. After he, like many of his friends from the Serakkreis, volunteered for the First World War , out of a sense of duty, but without the initially widespread enthusiasm for war , in which he was wounded and honored for bravery, his experience with the atrocities at the front gave way his initially only romantic-youthful opposition to a more well-founded critical attitude towards war, militarism, nationalism and chauvinism . He then joined the USPD and wrote articles for left-wing underground leaflets such as the Political Circulars , as well as secret circulars with clippings in the foreign press to his friends at the front. Later he belonged to the left wing of the Vienna Circle . In the United States he actively supported the civil rights and anti-Vietnam war movements . The FBI kept a file on Rudolf Carnap.


In his first major work The Logical Structure of the World (1928) Carnap advocated an empirical reconstruction of science. He tried to show that all terms that relate to the physical outside world, the mental states of others or to cultural-social processes can ultimately be traced back to an intrinsic psychological basis (to elementary experiences ), i.e. H. on terms that relate to the respective subjective stream of experience of an observer.

In pseudo-problems in philosophy. The Alien Psychic and the Realism Controversy (1928) and the essay Overcoming Metaphysics by Logical Analysis of Language (1932) he accused the traditional problems of metaphysics of meaninglessness on the basis of verificationistic semantics . Among the contemporary philosophers, he particularly criticized Martin Heidegger . In 1930 he founded the philosophical journal Knowledge with Hans Reichenbach .

In the early 1930s, under the influence of Otto Neurath , Carnap increasingly distanced himself from the idea of ​​a constitutional system with an intrinsic psychological basis and developed, among other things, in his essay The physical language as the universal language of science (1931), a physicalistic conception of language within which intrinsic psychological phenomena are no longer present , but intersubjectively accessible physical objects are the primary reference objects.

In his second major work, Logical Syntax of Language (1934), Carnap argued that philosophy should be replaced by “science logic ” - ie. H. by the logical analysis of scientific language - to replace:

“We want to understand the term 'science logic' in a very broad sense. It is intended to mean the area of ​​all the questions that are usually referred to as pure and applied logic, as a logical analysis of the individual areas of science or science as a whole, as epistemology, as fundamental problems or similar. "

- Rudolf Carnap : Logical Syntax of Language

His third major work Meaning and Necessity: A Study in Semantics and Modal Logic (1947; German importance and necessity ) dealt with the modal logic foundations of the philosophy of language . In the philosophy of the mind , Carnap was close to behaviorism .

Carnap was particularly interested in the construction of formal logic systems. With his “ tolerance principle” and the principle of the conventionality of language forms, however, he always emphasized the multitude of alternative language calculi. He also made significant contributions in the field of probability theory . In his fourth major work Logical Foundations of Probability (1950, German Inductive Logic and Probability as an abridged version) he dealt with questions of inductive probabilities and differentiated between statistical and logical probability. He was reacting to the epistemological work of Karl Popper , whose criticism of inductivism he partially accepted, but whose deductivism he strictly rejected as impracticable for real scientific theories because of their predominantly probabilistic nature. Carnap continued to defend the notion of an increased probability of empirically well-confirmed scientific theories. Today, for example, the Bayesian model of confirming empirical theories is seen as part of Carnap's tradition . In the meantime, as part of the structuralist theory concept , in which model classes take on the role of sentences, it has been possible to introduce the concept of probability in such a way that degrees of confirmation for theories other than zero can be calculated. Since this means that the possibility of calculating degrees of confirmation also for real scientific theories moves into the realm of possibility, this represents an important step in Carnap's tradition.

In meta-ethics he took a position called “ emotivism ” (or “non-cognitivism”), according to which absolute value statements about what should be done have emotive and motivative, but no cognitive, meaning components. This was also the reason why he refrained from including ethical and socio-political thoughts in his philosophical work, which contributed to the error that these were simply not relevant to him.


Carnap had a lasting influence on the development of analytical philosophy , which, however, was v. a. began to detach from him since the middle of the 20th century. The view that the task of philosophy essentially consists in the construction of artificial, logically stringent “scientific languages” was pushed back in the context of the linguistic turn in favor of the analysis of normal colloquial language; Ludwig Wittgenstein's late work was particularly important here, and Carnap presumably took no notice of it.

In his essay "Two Dogmas of Empiricism", Willard van Orman Quine questioned Carnap's strict differentiation between logical-analytical and empirical truths. On the one hand, "analyticity" and "meaning" are problematic or difficult to define terms, on the other hand, the meaning of terms is only to be examined empirically and thus never finally clarified. Carnap opposed this criticism by differentiating between natural and artificial languages; in the latter (which he was mainly concerned with) the meaning of concepts and the logical / analytical truth of sentences could simply be determined by resolution.

In the field of induction, Carnap was particularly criticized by Karl Popper , who in his “Logic of Research” rejected all inductivist positions of confirmation with regard to empirical theories and replaced them with a hypothetical deductivism; He also rejected all attempts to establish an empirical criterion of meaning ; instead, a criterion of demarcation between empirical science and metaphysics should be sought. Carnap tried to defend the idea of ​​an increased probability of empirically proven theories.

Today's analytical philosophers orient themselves more towards the precise style of philosophizing that Carnap tried to establish, less towards its content-related positions. Since the 1980s at the latest, so-called “analytical metaphysics” has been one of the most flourishing branches of analytical philosophy (see also: Analytical ontology ).


In 1948 Carnap was elected to the American Academy of Arts and Sciences . In 1955 he became a corresponding member of the British Academy .

Publications (selection)

  • The space. A contribution to science. Berlin 1922.
  • On the task of physics and the application of the principle of simplicity. In: Kant studies. Volume 28, 1923, pp. 90-107.
  • About the dependence of the properties of space on those of time. In: Kant studies. Volume 30, 1925, pp. 331-345.
  • Physical concept formation. Karlsruhe 1926.
  • Pseudo problems in philosophy. The alien psychic and the realism dispute. Berlin-Schlachtensee 1928. New edition Hamburg 2004, ISBN 978-3-7873-1728-8 .
  • The logical structure of the world . Berlin-Schlachtensee 1928. New edition. Hamburg 1998. ISBN 978-3-7873-1464-5 .
  • Outline of logistics, with special consideration of relational theory and its applications. Vienna 1929.
  • Mathematics as a branch of logic. In: Leaves for German Philosophy. Volume 4, 1930.
  • The logistic foundation of mathematics. In: Knowledge. Vol. 2, 1931/1932, pp. 91-105.
  • Overcoming metaphysics through logical analysis of language. In: Knowledge. Vol. 2, 1931/1932, pp. 219-241
  • The physical language as the universal language of science. In: Knowledge. Vol. 2, 1931/1932, pp. 432-465.
  • Psychology in physical language. In: Knowledge. Vol. 3, 1932/1933, pp. 107-142.
  • Logical syntax of the language. Vienna 1934; 2nd edition 1968.
  • Testability and Meaning. In: Philosophy of Science. Vol. 3, 1936, pp. 419-471, and Vol. 4, 1937, pp. 1-40.
  • as ed. with Otto Neurath and Charles Morris (ed.): International Encyclopedia of Unified Science . Vol. 2 volumes. University of Chicago Press, Chicago / Cambridge University Press, Cambridge 1938 ff .:
  • with Otto Neurath, Niels Bohr , John Dewey , Bertrand Russell and Charles W. Morris : Encylopedia and Unified Science (= International Encyclopedia of Unified Science. Volume 1, No. 1). Chicago 1938.
  • Foundations of Logic and Mathematics (= International Encyclopedia of Unified Science. Volume 1, No. 3). Chicago 1939; 12th edition 1967.
  • Introduction to Semantics . Harvard 1942.
  • Formalization of Logic . Harvard 1943.
  • Meaning and Necessity: A Study in Semantics and Modal Logic , Chicago 1947, exp. 1956 edition.
  • Logical Foundations of Probability . Chicago 1950.
  • Empiricism, Semantics, and Ontology , from Revue Internationale de Philosophie. Vol. 4, 1950 pp. 20-40
  • The Continuum of Inductive Methods. Chicago 1952.
  • Together with Y. Bar Hillel: An outline of the theory of Semantic information . Research Laboratory of Electronic, Massachusetts Institute of Technology , Report No. 247, 1952.
  • Introduction to symbolic logic, with special attention to its applications. Vienna 1954, 2nd edition 1960
  • Introduction to Symbolic Logic with Applications . Dover 1958.
  • Inductive logic and probability . Vienna 1959.
  • Intellectual Autobiography . In: PA Schilpp (Ed.): The Philosophy of Rudolf Carnap . Open Court, La Salle (Illinois) 1963 (see below).
  • Philosophical Foundations of Physics . New York 1966.
  • Introduction to the philosophy of natural science , original title Philosophical Foundations of Physics , trans. by Walter Hoering, Nymphenburger Verlagshandlung, Munich 1969.
  • Studies in inductive logic and probability . Vol. 1, Berkeley 1971.
  • Foundations of Logic and Mathematics (original title Foundations of Logic and Mathematics [1939]). Translated with an afterword and a critical bibliography by Walter Hoering, Munich 1973.
  • Two essays on entropy . Posthumously ed. by Abner Shimony, Berkeley 1977.
  • Studies in inductive logic and probability . Vol. 2, posthumously edited. by RC Jeffrey, Berkeley 1980.
  • Mein Weg in die Philosophie (independently published German translation of “Intellectual Autobiography” [1963]). Stuttgart 1993.


  • Steve Awodey (Ed.): Carnap Brought Home: The View from Jena . Open Court, La Salle, Ill. 2004. ISBN 0-8126-9550-X
  • Creath Friedman (Ed.): The Cambridge Companion to Carnap . Cambridge University Press, Cambridge 2008. ISBN 0-521-54945-0
  • Rudolf Haller : Neopositivism. A historical introduction to the philosophy of the Vienna Circle . Scientific Book Society, Darmstadt 1993.
  • Lothar Krauth: Carnap's philosophy . Springer, Vienna 1970.
  • Thomas Mormann: Rudolf Carnap . CH Beck, Munich 2000.
  • Paul Arthur Schilpp (Ed.): The Philosophy of Rudolf Carnap . Open Court, La Salle (Illinois) 1963.
  • Jan Sebestik, Antonia Soulez: Le Cercle de Vienne: Doctrines et Controverses . L'Harmattan, Paris 2001.
  • Wolfgang Spohn (Ed.): Knowledge Orientated. A Centennial Volume for Rudolf Carnap and Hans Reichenbach . Kluwer Academic Publishers, Dordrecht among others 1991.
  • Pierre Wagner (Ed.): Carnap's Logical Syntax of Language . Palgrave Macmillan, Basingstoke 2009.
  • Pierre Wagner (Ed.): Carnap's Ideal of Explication and Naturalism . Palgrave Macmillan, Basingstoke 2012.

Web links

Commons : Rudolf Carnap  - collection of images, videos and audio files

Individual evidence

  1. a b Rudolf Carnap . Portal Rhenish History; Retrieved February 9, 2013.
  2. ^ Thomas Mormann: Rudolf Carnap . Beck's series Denker, Verlag CH Beck, Munich 2000.
  3. ^ R. Carnap: Intellectual Autobiography . In: PA Schilpp (Ed.): The Philosophy of Rudolf Carnap . Open Court, La Salle (Illinois) 1963.
  4. Thomas Mormann: Introduction . In: Rudolf Carnap: Scheinprobleme in der Philosophie and other metaphysics-critical writings. Hamburg 2004.
  5. ^ Thomas Mormann: Rudolf Carnap . Beck's series Denker, Verlag CH Beck, Munich 2000.
  6. ^ AW Carus: Carnap's intellectual development . In: M. Friedman, R. Creath (editors): The Cambridge Companion to CARNAP . Cambridge University Press, Cambridge 2007, ISBN 978-0-521-54945-5 .
  7. Rudolph Carnap, accessed April 11, 2011.
  8. ^ Rudolf Carnap: Logical Syntax of Language. Vienna 1934. Quoted from: PV Tavanec, VS Švyrjev: The logic of scientific knowledge. In: Studies on the Logic of Scientific Knowledge. Akademie Verlag, Berlin 1967. (Moscow 1964). P. 25. Note 2.
  9. ^ Bernhard Lauth : Probability, Confirmation and Testing from a Structuralist Perspective . In: Balzer, Moulines (Ed.): Structuralist Theory of Science: Focal Issues, New Results . 1996, pp. 115-137.
  10. Wolfgang Balzer: Science and its methods. Principles of the philosophy of science Alber, Freiburg i. B. 1997, ISBN 3-495-47853-1 , p. 314.
  11. Rudolph Carnap: Starting points. My way into philosophy . Stuttgart 1993 (1963), p. 36 f.
  12. Cf. for example the afterword by Willy Hochkeppel in Carnap's autobiography "Mein Weg in die Philosophie", Stuttgart 1993 (1963).
  13. ^ Members of the American Academy. Listed by election year, 1900-1949 . (PDF); accessed on October 11, 2015
  14. ^ Deceased Fellows. British Academy, accessed March 5, 2020 .
  15. Excerpt in: Martin Morgenstern , Robert Zimmer (Ed.): Meeting point philosophy. Realities and worldviews. (Volume 5 of the series) Bayerischer Schulbuch Verlag, Munich 2002, ISBN 3-7627-0326-4 & Patmos, Düsseldorf 2002, ISBN 3-491-75642-1 , pp. 124–127