Rudolf Carnap

Rudolf Carnap (/ˈkɑːrnæp/;[15] German: [ˈkaɐ̯naːp]; May 18, 1891 – September 14, 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. He is considered "one of the giants among twentieth-century philosophers."[16]

Rudolf Carnap
BornMay 18, 1891
DiedSeptember 14, 1970 (aged 79)
EducationUniversity of Jena (PhD, 1921)
Era20th-century philosophy
RegionWestern philosophy
Vienna Circle
Logical positivism
Logical atomism[2]
Logical behaviorism[3]
ThesisDer Raum (Space) (1921)
Main interests
Logic · Epistemology
Philosophy of science
Notable ideas
Phenomenalism in linguistic terms
Logical behaviorism[3]
Analytic–synthetic distinction (revised)
Internal–external distinction
Semantics for modal logic
Constructed systems
Conceptual schemes
Formal epistemology
Framework-relative constitutive a priori[5]
Beobachtungssatz (observational statement)
Carnap's categoricity (Monomorphie)[7] problem
Forkability theorem (Gabelbarkeitssatz): "every complete axiom system is also categorical (monomorph)"[8][9]
Logical positivism
Epistemic structural realism[10]
L-true (logically true) statements[11]
Carnap sentences[11]
Three kinds of space: formal, physical and perceptual
Elimination of metaphysics through logical analysis[12]
Carnapian explication[13]
Principle of tolerance[14]

Life and work

Wuppertal Ronsdorf - Villa Carnap 01 ies
Carnap's birthplace in Wuppertal

Carnap's father had risen from the status of a poor ribbon-weaver to become the owner of a ribbon-making factory. His mother came from academic stock; her father was an educational reformer and her oldest brother was the archaeologist Wilhelm Dörpfeld. As a ten-year-old, Carnap accompanied his uncle on an expedition to Greece.[17] Carnap was raised in a religious family, but later became an atheist.[18]

He began his formal education at the Barmen Gymnasium. From 1910 to 1914, he attended the University of Jena, intending to write a thesis in physics. But he also studied carefully Kant's Critique of Pure Reason during a course taught by Bruno Bauch, and was one of very few students to attend Gottlob Frege's courses in mathematical logic. While Carnap held moral and political opposition to World War I, he felt obligated to serve in the German army. After three years of service, he was given permission to study physics at the University of Berlin, 1917–18, where Albert Einstein was a newly appointed professor. Carnap then attended the University of Jena, where he wrote a thesis defining an axiomatic theory of space and time. The physics department said it was too philosophical, and Bruno Bauch of the philosophy department said it was pure physics. Carnap then wrote another thesis in 1921, with Bauch's supervision, on the theory of space in a more orthodox Kantian style, and published as Der Raum (Space) in a supplemental issue of Kant-Studien (1922).

Frege's course exposed him to Bertrand Russell's work on logic and philosophy, which put a sense of the aims to his studies. He accepted the effort to surpass traditional philosophy with logical innovations that inform the sciences. He wrote a letter to Russell, who responded by copying by hand long passages from his Principia Mathematica for Carnap's benefit, as neither Carnap nor his university could afford a copy of this epochal work. In 1924 and 1925, he attended seminars led by Edmund Husserl,[19] the founder of phenomenology, and continued to write on physics from a logical positivist perspective.

Carnap discovered a kindred spirit when he met Hans Reichenbach at a 1923 conference. Reichenbach introduced Carnap to Moritz Schlick, a professor at the University of Vienna who offered Carnap a position in his department, which Carnap accepted in 1926. Carnap thereupon joined an informal group of Viennese intellectuals that came to be known as the Vienna Circle, directed largely by Moritz Schlick and including Hans Hahn, Friedrich Waismann, Otto Neurath, and Herbert Feigl, with occasional visits by Hahn's student Kurt Gödel. When Wittgenstein visited Vienna, Carnap would meet with him. He (with Hahn and Neurath) wrote the 1929 manifesto of the Circle, and (with Hans Reichenbach) initiated the philosophy journal Erkenntnis.

In February 1930 Tarski lectured in Vienna, and during November 1930 Carnap visited Warsaw. On these occasions he learned much about Tarski's model theoretic method of semantics. Rose Rand, another philosopher in the Vienna Circle, noted, "Carnap's conception of semantics starts from the basis given in Tarski's work but a distinction is made between logical and non-logical constants and between logical and factual truth... At the same time he worked with the concepts of intension and extension and took these two concepts as a basis of a new method of semantics."[20]

In 1931, Carnap was appointed Professor at the German University of Prague. In 1933, W. V. Quine met Carnap in Prague and discussed the latter's work at some length. Thus began the lifelong mutual respect these two men shared, one that survived Quine's eventual forceful disagreements with a number of Carnap's philosophical conclusions.

Carnap, whose socialist and pacifist beliefs put him at risk in Nazi Germany, emigrated to the United States in 1935 and became a naturalized citizen in 1941. Meanwhile, back in Vienna, Moritz Schlick was murdered in 1936. From 1936 to 1952, Carnap was a professor of philosophy at the University of Chicago. During the late 1930s, Carnap offered an assistant position in philosophy to Carl Gustav Hempel, who accepted and became one of his most significant intellectual collaborator. Thanks partly to Quine's help, Carnap spent the years 1939–41 at Harvard, where he was reunited with Tarski. Carnap (1963) later expressed some irritation about his time at Chicago, where he and Charles W. Morris were the only members of the department committed to the primacy of science and logic. (Their Chicago colleagues included Richard McKeon, Mortimer Adler, Charles Hartshorne, and Manley Thompson.) Carnap's years at Chicago were nonetheless very productive ones. He wrote books on semantics (Carnap 1942, 1943, 1956), modal logic, and on the philosophical foundations of probability and induction (Carnap 1950, 1952).

After a stint at the Institute for Advanced Study in Princeton, he joined the philosophy department at UCLA in 1954, Hans Reichenbach having died the previous year. He had earlier refused an offer of a similar job at the University of California, because accepting that position required that he sign a loyalty oath, a practice to which he was opposed on principle. While at UCLA, he wrote on scientific knowledge, the analyticsynthetic dichotomy, and the verification principle. His writings on thermodynamics and on the foundations of probability and induction, were published posthumously as Carnap (1971, 1977, 1980).

Carnap taught himself Esperanto when he was 14 years of age, and remained sympathetic to it (Carnap 1963). He later attended the World Congress of Esperanto in 1908 and 1922, and employed the language while traveling.

Carnap had four children by his first marriage to Elizabeth Schöndube, which ended in divorce in 1929. He married his second wife, Elizabeth Ina Stöger, in 1933.[17] Ina committed suicide in 1964.

Topics in the development of Carnap's philosophy

Below is an examination of the main topics in the evolution of the philosophy of Rudolf Carnap. It is not exhaustive, but it outlines Carnap's main works and contributions to modern epistemology and philosophy of logic.

PhD dissertation

From 1919 to 1921, Carnap worked on a doctoral thesis called “Der Raum. Ein Beitrag zur Wissenschaftslehre” (1922). In this dissertation on the philosophical foundations of geometry, Carnap tried to provide a logical basis for a theory of space and time in physics. Considering that Carnap was interested in pure mathematics, natural sciences and philosophy, his dissertation can be seen as an attempt to build a bridge between the different disciplines that are geometry, physics and philosophy. For Carnap thought that in many instances those disciplines use the same concepts, but with totally different meanings. The main objective of Carnap's dissertation was to show that the inconsistencies between theories concerning space only existed because philosophers, as well as mathematicians and scientists, were talking about different things while using the same “space” word. Hence, Carnap characteristically argued that there had to be three separate notions of space. “Formal” space is space in the sense of mathematics: it is an abstract system of relations. “Intuitive” space is made of certain contents of intuition independent of single experiences. “Physical” space is made of actual spatial facts given in experience. The upshot is that those three kinds of “space” imply three different kinds of knowledge and thus three different kinds of investigations. It is interesting to note that it is in this dissertation that the main themes of Carnap's philosophy appear, most importantly the idea that many philosophical contradictions appear because of a misuse of language, and a stress on the importance of distinguishing formal and material modes of speech.  

Der Logische Aufbau der Welt

From 1922 to 1925, Carnap worked on a book which became one of his major works, namely Der logische Aufbau der Welt (1928) (translated as “The logical structure of the world”, 1967). That achievement has become a landmark in modern epistemology and can be read as a forceful statement of the philosophical thesis of logical positivism. Indeed, the Aufbau suggests that epistemology, based on modern symbolic logic, is concerned with the logical analysis of scientific propositions, while science itself, based on experience, is the only source of knowledge of the external world, i.e. the world outside the realm of human perception. According to Carnap, philosophical propositions are statements about the language of science; they aren’t true or false, but merely consist of definitions and conventions about the use of certain concepts. In contrast, scientific propositions are factual statements about the external reality. They are meaningful because they are based on the perceptions of the senses. In other words, the truth or falsity of those propositions can be verified by testing their content with further observations.  

In the Aufbau, Carnap wants to display the logical and conceptual structure with which all scientific (factual) statements can be organized. Carnap gives the label “constitutional” to this epistemic-logical project. It is a constructive undertaking that systematizes scientific knowledge according to the notions of symbolic logic. Accordingly, the purpose of this constitutional system is to identify and discern different classes of scientific concepts and to specify the logical relations that link them. In the Aufbau, concepts are taken to denote objects, relations, properties, classes and states. Carnap argues that all concepts must be ranked over a hierarchy. In that hierarchy, all concepts are organized according to a fundamental arrangement where concepts can be reduced and converted to other basic ones. Carnap explains that a concept can be reduced to another when all sentences containing the first concept can be transformed into sentences containing the other. In other words, every scientific sentence should be translatable into another sentence such that the original terms have the same reference as the translated terms. Most significantly, Carnap argues that the basis of this system is psychological. Its content is the “immediately given”, which is made of basic elements, namely perceptual experiences. These basic elements consist of conscious psychological states of a single human subject. In the end, Carnap argues that his constitutional project demonstrates the possibility of defining and uniting all scientific concepts in a single conceptual system on the basis of a few fundamental concepts.    

Overcoming metaphysics

From 1928 to 1934, Carnap published papers (Scheinprobleme in der Philosophie, 1928 – translated as “Pseudoproblems in Philosophy”, 1967) in which he appears overtly skeptical of the aims and methods of metaphysics, i.e. the traditional philosophy that finds its roots in mythical and religious thought. Indeed, he discusses how, in many cases, metaphysics is made of meaningless discussions of pseudo-problems. For Carnap, a pseudo-problem is a philosophical question which, on the surface, handles concepts that refer to our world while, in fact, these concepts do not actually denote real and attested objects. In other words, these pseudo-problems concern statements that do not, in any way, have empirical implications. They do not refer to states of affairs and the things they denote cannot be perceived. Consequently, one of Carnap's main aim has been to redefine the purpose and method of philosophy. According to him, philosophy should not aim at producing any knowledge transcending the knowledge of science. In contrast, by analyzing the language and propositions of science, philosophers should define the logical foundations of scientific knowledge. Using symbolic logic, they should explicate the concepts, methods and justificatory processes that exist in science.

Carnap believed that the difficulty with traditional philosophy lay in the use of concepts that are not useful for science. For Carnap, the scientific legitimacy of these concepts was doubtful, because the sentences containing them do not express facts. Indeed, a logical analysis of those sentences proves that they do not convey the meaning of states of affairs. In other words, theses sentences are meaningless. Carnap explains that to be meaningful, a sentence should be factual. It can be so, for one thing, by being based on experience, i.e. by being formulated with words relating to direct observations. For another, a sentence is factual if one can clearly state what are the observations that could confirm or disconfirm that sentence. After all, Carnap presupposes a specific criterion of meaning, namely the Wittgensteinian principle of verifiability. Indeed, he requires, as a precondition of meaningfulness, that all sentences be verifiable, what implies that a sentence is meaningful only if there is a way to verify if it is true or false. To verify a sentence, one needs to expound the empirical conditions and circumstances that would establish the truth of the sentence. As a result, it is clear for Carnap that metaphysical sentences are meaningless. They include concepts like “god”, “soul” and “the absolute” that transcend experience and cannot be traced back or connected to direct observations. Because those sentences cannot be verified in any way, Carnap suggests that science, as well as philosophy, should neither consider nor contain them.

The logical analysis of language

At that point in his career, Carnap attempted to develop a full theory of the logical structure of scientific language. This theory, exposed in Logische Syntax der Sprache (1934) (translated as “The logical syntax of language”, 1937) gives the foundations to his idea that scientific language has a specific formal structure and that its signs are governed by the rules of deductive logic. Moreover, the theory of logical syntax expounds a method with which one can talk about a language: it is a formal meta-theory about the pure forms of language. In the end, because Carnap argues that philosophy aims at the logical analysis of the language of science and thus is the logic of science, the theory of the logical syntax can be considered as a definite language and a conceptual framework for philosophy.

The logical syntax of language is a formal theory. It is not concerned with the contextualized meaning or the truth-value of sentences. In contrast, it considers the general structure of a given language and explores the different structural relations that connect the elements of that language. Hence, by explaining the different operations that allow specific transformations within the language, the theory is a systematic exposition of the rules that operate within that language. In fact, the basic function of these rules is to provide the principles to safeguard coherence, to avoid contradictions and to deduce justified conclusions. It is to be noted that Carnap sees language as a calculus. This calculus is a systematic arrangement of symbols and relations. The symbols of the language are organized according to the class they belong to and it is through their combination that we can form sentences. The relations are different conditions under which a sentence can be said to follow, or to be the consequence, of another sentence. The definitions included in the calculus state the conditions under which a sentence can be considered of a certain type and how those sentences can be transformed. We can see the logical syntax as a method of formal transformation, i.e. a method for calculating and reasoning with symbols.

It is in the logical syntax that Carnap introduces his notable principle of tolerance. This principle suggests that there is no moral in logic. When it comes to using a language, there is no good or bad, fundamentally true or false. In this perspective, the philosopher's task is not to bring authoritative interdicts prohibiting the use of certain concepts. In contrast, philosophers should seek general agreements over the relevance of certain logical devices. According to Carnap, those agreements are possible only through the detailed presentation of the meaning and use of the expressions of a language. In other words, Carnap believes that every logical language is correct only if this language is supported by exact definitions and not by philosophical presumptions. It is to be noted that Carnap embraces a formal conventionalism. That implies that formal languages are constructed and that everyone is free to choose the language it finds more suited to his purpose. There should not be any controversy over which language is the correct language; what matters is agreeing over which language best suits a particular purpose. Carnap explains that the choice of a language should be guided according to the security it provides against logical inconsistency. Furthermore, practical elements like simplicity and fruitfulness in certain tasks influence the choice of a language. Clearly enough, the principle of tolerance was a sophisticated device introduced by Carnap to dismiss any form of dogmatism in philosophy.    

Inductive logic

After having considered problems in semantics, i.e. the theory of the concepts of meaning and truth (Foundations of Logic and Mathematics, 1939; Introduction to Semantics, 1942; Formalization of Logic, 1943), Carnap turned his attention to the subject of probability and inductive logic. His views on that subject are for the most part exposed in Logical foundations of probability (1950) where Carnap aims to give a sound logical interpretation of probability. Carnap thought that according to certain conditions, the concept of probability had to be interpreted as a purely logical concept. In this view, probability is a basic concept anchored in all inductive inferences, whereby the conclusion of every inference that holds without deductive necessity is said be more or less likely to be the case. In fact, Carnap claims that the problem of induction is a matter of finding a precise explanation of the logical relation that holds between a hypothesis and the evidence that supports it. An inductive logic is thus based on the idea that probability is a logical relation between two types of statements: the hypothesis (conclusion) and the premises (evidence). Accordingly, a theory of induction should explain how, by pure logical analysis, we can ascertain that certain evidence establishes a degree of confirmation strong enough to confirm a given hypothesis.

Carnap was convinced that there was a logical as well as an empirical dimension in science. He believed that one had to isolate the experiential elements from the logical elements of a given body of knowledge. Hence, the empirical concept of frequency used in statistics to describe the general features of certain phenomena can be distinguished from the analytical concepts of probability logic that merely describe logical relations between sentences. For Carnap, the statistical and the logical concepts must be investigated separately. Having insisted on this distinction, Carnap defines two concepts of probability. The first one is logical and deals with the degree to which a given hypothesis is confirmed by a piece of evidence. It is the degree of confirmation. The second is empirical, and relates to the long run rate of one observable feature of nature relative to another. It is the relative frequency. Statements belonging to the second concepts are about reality and describe states of affairs. They are empirical and, therefore, must be based on experimental procedures and the observation of relevant facts. On the contrary, statements belonging to the first concept do not say anything about facts. Their meaning can be grasped solely with an analysis of the signs they contain. They are analytical sentences, i.e. true by virtue of their logical meaning. Even though these sentences could refer to states of affairs, their meaning is given by the symbols and relations they contain. In other words, the probability of a conclusion is given by the logical relation it has to the evidence. The evaluation of the degree of confirmation of a hypothesis is thus a problem of meaning analysis.

Clearly, the probability of a statement about relative frequency can be unknown; because it depends on the observation of certain phenomena, one may not possess the information needed to establish the value of that probability. Consequently, the value of that statement can be confirmed only if it is corroborated with facts. In contrast, the probability of a statement about the degree of confirmation could be unknown, in the sense that one may miss the correct logical method to evaluate its exact value. But, such a statement can always receive a certain logical value, given the fact that this value only depends on the meaning of its symbols.              

Primary source materials

The Carnap Papers consist of approximately 10,000 personal letters of correspondence. The papers were donated by his daughter, Hanna Carnap-Thost in 1974. Documents that contain financial, medical, and personal information are restricted.[21] These were written over his entire life and career. Carnap used the mail regularly to discuss philosophical problems with hundreds of others. The most notable were: Herbert Feigl, Carl Gustav Hempel, Felix Kaufmann, Otto Neurath, and Moritz Schlick. Photographs are also part of the collection and were taken throughout his life. Family pictures and photographs of his peers and colleagues are also stored in the collection. Some of the correspondence is considered notable and consist of his student notes, his seminars with Frege, (describing the Begriffsschrift and the logic in mathematics). Carnap's notes from Russell's seminar in Chicago, and notes he took from discussions with Tarski, Heisenberg, Quine, Hempel, Gödel, Jeffrey are part of the University of Pittsburgh's Archives and Collections. Digitized contents include:

  • Notes (old), 1958-1966[22]

More than 1,000 pages of lecture outlines are preserved that cover the courses that Carnap taught in the United States, Prague, and Vienna, Prague. Drafts of his published works and unpublished works are part of the collection. includes manuscript drafts and typescripts both for his published works and for many unpublished papers and books. A partial listing include his first formulations of his "Aufbau". "Quasizerlegung"(1932), and "Vom Chaos zur Wirklichkeit"(1922) "Topologie der Raum-Zeit-Welt" (Topology of the Space-Time World, 1924) is his later 104-page piece about a logical reconstruction of the space-time framework without the use of mathematics. The holdings include a large number of unpublished papers. Much material is written in an older German shorthand, the Stolze-Schrey system. He employed this writing system extensively beginning in his student days.[21] Much of the content has been digitized. The University of California also maintains a collection of Rudolf Carnap Papers. Microfilm copies of his papers are maintained by the Philosophical Archives at the University of Konstanz in Germany.[23]

Selected publications

  • 1922. Der Raum: Ein Beitrag zur Wissenschaftslehre, Kant-Studien, Ergänzungshefte, no. 56. His Ph.D. thesis.
  • 1926. Physikalische Begriffsbildung. Karlsruhe: Braun.
  • 1928. Scheinprobleme in der Philosophie (Pseudoproblems of Philosophy). Berlin: Weltkreis-Verlag.
  • 1928. Der Logische Aufbau der Welt. Leipzig: Felix Meiner Verlag. English translation by Rolf A. George, 1967. The Logical Structure of the World. Pseudoproblems in Philosophy. University of California Press. ISBN 0-812-69523-2
  • 1929. Abriss der Logistik, mit besonderer Berücksichtigung der Relationstheorie und ihrer Anwendungen. Springer.[24]
  • 1934. Logische Syntax der Sprache. English translation 1937, The Logical Syntax of Language. Kegan Paul.[25]
  • 1996 (1935). Philosophy and Logical Syntax. Bristol UK: Thoemmes. Excerpt.
  • 1939, Foundations of Logic and Mathematics in International Encyclopedia of Unified Science, Vol. I, no. 3. University of Chicago Press.[26]
  • 1942. Introduction to Semantics. Harvard Uni. Press.
  • 1943. Formalization of Logic. Harvard Uni. Press.
  • 1945. On Inductive Logic in Philosophy of Science, Vol.12, p. 72-97.
  • 1945. The Two Concepts of Probability in Philosophy and Phenomenological Research, Vol.5, No.4 (Jun), p. 513-532.
  • 1947. On the Application of Inductive Logic] in Philosophy and Phenomenological Research, Vol. 8, p. 133-148.
  • 1956 (1947). Meaning and Necessity: a Study in Semantics and Modal Logic. University of Chicago Press.
  • 1950. Logical Foundations of Probability. University of Chicago Press. Pp. 3–15 online.
  • 1950. "Empiricism, Semantics, Ontology", Revue Internationale de Philosophie 4: 20–40.
  • 1952. The Continuum of Inductive Methods. University of Chicago Press.
  • 1958. Introduction to Symbolic Logic and its Applications. Dover publications, New York. ISBN 9780486604534
  • 1963, "Intellectual Autobiography" in Schilpp (1963: 1–84).
  • 1966. Philosophical Foundations of Physics. Martin Gardner, ed. Basic Books. Online excerpt.
  • 1971. Studies in inductive logic and probability, Vol. 1. University of California Press.
  • 1977. Two essays on entropy. Shimony, Abner, ed. University of California Press.
  • 1980. Studies in inductive logic and probability, Vol. 2. Jeffrey, R. C., ed. University of California Press.
  • 2000. Untersuchungen zur Allgemeinen Axiomatik. Edited from unpublished manuscript by T. Bonk and J. Mosterín. Darmstadt: Wissenschaftliche Buchgesellschaft. 167 pp. ISBN 3-534-14298-5.

Online bibliography. Under construction, with no entries dated later than 1937.


  • Interview with Rudolf Carnap, German TV, 1964.


  1. ^ "Review of Gonzalo Rodriguez-Pereyra, Resemblance Nominalism: A Solution to the Problem of Universals" –
  2. ^ Carnap, R. (1934), "On the Character of Philosophic Problems (Über den Charakter der philosophischen Probleme)," translation by W. M. Malisoff, Philosophy of Science, 1, pp. 5–19.
  3. ^ a b Zalta, Edward N. (ed.). "Behaviorism". Stanford Encyclopedia of Philosophy.
  4. ^ Physicalism (Stanford Encyclopedia of Philosophy)
  5. ^ Arthur Sullivan, The Constitutive A Priori: Developing and Extending an Epistemological Framework, Lexington Books, 2018, p. 106.
  6. ^ Rudolf Carnap, The Logical Syntax of Language, Routledge & Kegan Paul, 1937, pp. 13–14.
  7. ^ A. W. Carus, Carnap and Twentieth-Century Thought: Explication as Enlightenment, Cambridge University Press, 2007, p. 222.
  8. ^ A. W. Carus, Carnap and Twentieth-Century Thought: Explication as Enlightenment, Cambridge University Press, 2007, pp. 223 and 227; Thomas Uebel, Empiricism at the Crossroads: The Vienna Circle's Protocol-Sentence Debate Revisited, Open Court, 2015, p. 142.
  9. ^ Steve Awodey pronounces Carnap's Gabelbarkeitssatz-related pursuits "ill-fated" (Steve Awodey, "Structuralism, Invariance, and Univalence" (March 4, 2014)).
  10. ^ "Structural Realism": entry by James Ladyman in the Stanford Encyclopedia of Philosophy
  11. ^ a b c Carnap, Rudolf – Internet Encyclopedia of Philosophy
  12. ^ Rudolf Carnap, "Überwindung der Metaphysik durch logische Analyse der Sprache", Erkenntnis II (1932): 219–241.
  13. ^ Dutilh Novaes, Catarina; Reck, Erich (2017). "Carnapian explication, formalisms as cognitive tools, and the paradox of adequate formalization". Synthese. 194: 195–215. doi:10.1007/s11229-015-0816-z.
  14. ^ Richardson, Alan; Isaacson, Dan (1994). "Carnap's Principle of Tolerance". Proceedings of the Aristotelian Society, Supplementary Volumes. 68: 67–83. JSTOR 4107023.
  15. ^ "Carnap". Random House Webster's Unabridged Dictionary.
  16. ^ California Digital Library
  17. ^ a b Quine, W.V. and Rudolf Carnap (1990). Dear Carnap, Dear Van: The Quine-Carnap Correspondence and Related Work. Berkeley, CA: University of California Press. p. 23.
  18. ^ "Carnap had a modest but deeply religious family background, which might explain why, although he later became an atheist, he maintained a respectful and tolerant attitude in matters of faith throughout his life." Buldt, Bernd: "Carnap, Paul Rudolf", Complete Dictionary of Scientific Biography Vol. 20 p.43. Detroit: Charles Scribner's Sons, 2008.
  19. ^ Smith, D. W., and Thomasson, Amie L. (eds.), 2005, Phenomenology and Philosophy of Mind. Oxford and New York: Oxford University Press, p. 8 n. 18.
  20. ^ Rand, Rose. "Reading Notes and Summaries on Works by Rudolph Carnap, 1932 and Undated" (PDF). Rose Rand Papers. Special Collections Department, University of Pittsburgh. Retrieved May 16, 2013.
  21. ^ a b "Guides to Archives and Manuscript Collections at the University of Pittsburgh Library System". Missing or empty |url= (help); |access-date= requires |url= (help)
  22. ^ "AS Notes (old), 1958-1966 Box 19, Folder 7 Rudolf Carnap Papers, 1905-1970, ASP.1974.01, Special Collections Department, University of Pittsburgh" (PDF). Retrieved 2015-12-02.
  23. ^ "Finding Aid for the Rudolf Carnap papers, 1920-1968". Retrieved 2015-12-02.
  24. ^ Weiss, Paul (1929). "Review: Abriss der Logistik by Rudolf Carnap" (PDF). Bull. Amer. Math. Soc. 35 (6): 880–881. doi:10.1090/s0002-9904-1929-04818-3.
  25. ^ Mac Lane, Saunders (1938). "Review: The Logical Syntax of Language by Rudolf Carnap, translated from the German by Amethe Smeaton" (PDF). Bull. Amer. Math. Soc. 44 (3): 171–176. doi:10.1090/S0002-9904-1938-06694-3.
  26. ^ Church, Alonzo (1939). "Review: Foundations of Logic and Mathematics by Rudolf Carnap" (PDF). Bull. Amer. Math. Soc. 45 (11): 821–822. doi:10.1090/s0002-9904-1939-07085-7.


  • Richard Creath, Michael Friedman, ed. (2007). The Cambridge companion to Carnap. Cambridge University Press. ISBN 0521840155.
  • Roger F Gibson, ed. (2004). The Cambridge companion to Quine. Cambridge University Press. ISBN 0521639492.
  • Ivor Grattan-Guinness, 2000. In Search of Mathematical Roots. Princeton Uni. Press.
  • Thomas Mormann, 2000. "Rudolf Carnap" (book). München, Beck.
  • Willard Quine
    • 1951, Two Dogmas of Empiricism. The Philosophical Review 60: 20–43. Reprinted in his 1953 From a Logical Point of View. Harvard University Press.
    • 1985, The Time of My Life: An Autobiography. MIT Press.
  • Richardson, Alan W., 1998. Carnap's construction of the world : the Aufbau and the emergence of logical empiricism. Cambridge Uni. Press.
  • Schilpp, P. A., ed., 1963. The Philosophy of Rudolf Carnap. LaSalle IL: Open Court.
  • Spohn, Wolfgang, ed., 1991. Erkenntnis Orientated: A Centennial Volume for Rudolf Carnap and Hans Reichenbach. Kluwer Academic Publishers.
  • 1991. Logic, Language, and the Structure of Scientific Theories: Proceedings of the Carnap-Reichenbach Centennial, University of Konstanz, May 21–24, 1991. University of Pittsburgh Press.
  • Wagner, Pierre, ed., 2009. Carnap's Logical Syntax of Language. Palgrave Macmillan.
  • Wagner, Pierre, ed., 2012. Carnap's Ideal of Explication and Naturalism. Palgrave Macmillan.

Further reading

  • Holt, Jim, "Positive Thinking" (review of Karl Sigmund, Exact Thinking in Demented Times: The Vienna Circle and the Epic Quest for the Foundations of Science, Basic Books, 449 pp.), The New York Review of Books, vol. LXIV, no. 20 (21 December 2017), pp. 74–76.

External links

Carnap Papers

The Rudolf Carnap Papers are a large collection of documents and photographs that record much of his life and career. They are used by scholars and historians not only for research into the life of Rudolf Carnap but also for research into his theories and the theories of other scholars with whom he corresponded. The Carnap papers are restored, maintained, cataloged and housed in the Archives Service Center, University Library System, University of Pittsburgh. They include extensive correspondence with others, lecture outlines for courses that he taught, and drafts of his published works and unpublished manuscripts. Much of the content of the Rudolf Carnap papers is available electronically and searchable through the finding aid through the archives. His work on metaphysics being essentially a question of semantics is still cited and have been further expanded by other scholars. His papers document his being considered a major contributor on the question of metaphysics. He was also a member of the Vienna Circle.

Constructional system

A constructional system or a constitution system is a system of objects or concepts of a certain domain in which all objects or concepts of that domain can be logically constructed from a proper subset of those objects or concepts, called the basis of the system. The notion of constructional systems can be traced back to Bertrand Russell, who wrote in 1914 that

The supreme maxim in scientific philosophising is this: wherever possible logical constructions are to be substituted for inferred entities.

German philosopher Rudolf Carnap in his Der logische Aufbau der Welt (1928) (referring to them as "Konstitutionssystems") and American philosopher Nelson Goodman in his The Structure of Appearance (1951) studied the structure of constructional systems.

Descriptive interpretation

According to Rudolf Carnap, in logic, an interpretation is a descriptive interpretation (also called a factual interpretation) if at least one of the undefined symbols of its formal system becomes, in the interpretation, a descriptive sign (i.e., the name of single objects, or observable properties). In his Introduction to Semantics (Harvard Uni. Press, 1942) he makes a distinction between formal interpretations which are logical interpretations (also called mathematical interpretation or logico-mathematical interpretation) and descriptive interpretations: a formal interpretation is a descriptive interpretation if it is not a logical interpretation.Attempts to axiomatize the empirical sciences, Carnap said, use a descriptive interpretation to model reality.: the aim of these attempts is to construct a formal system for which reality is the only interpretation. - the world is an interpretation (or model) of these sciences, only insofar as these sciences are true.Any non-empty set may be chosen as the domain of a descriptive interpretation, and all n-ary relations among the elements of the domain are candidates for assignment to any predicate of degree n.

Ernest Nagel

Ernest Nagel (November 16, 1901 – September 20, 1985) was an American philosopher of science. Along with Rudolf Carnap, Hans Reichenbach, and Carl Hempel, he is sometimes seen as one of the major figures of the logical positivist movement.


As introduced by Kurt Lewin, genidentity is an existential relationship underlying the genesis of an object from one moment to the next. What we usually consider to be an object really consists of multiple entities, which are the phases of the object at various times. Two objects are not identical because they have the same properties in common, but because one has developed from the other.

Lewin introduced the concept in his 1922 Habilitationsschrift Der Begriff der Genese in Physik, Biologie und Entwicklungsgeschichte. It is today perhaps the only surviving evidence of Lewin's influence on the philosophy of science. However, this concept never became an object of widespread discussion and debate in its own terms. Rather, it was extracted from its context by philosophers such as Rudolf Carnap, Hans Hermes, Hans Reichenbach, Adolph Grünbaum, and Bas van Fraassen who incorporated this concept into their own theories such as the topology of the universe or the axiomatization of mechanics. Lewin's idea was to compare and contrast the concept of genidentity in various branches of science, thereby laying bare the characteristic structure of each and making their classification possible in the first place.

Gustav Bergmann

Gustav Bergmann (May 4, 1906 – April 21, 1987) was an Austrian-born American philosopher. He studied at the University of Vienna and was a member of the Vienna Circle. Bergmann was influenced by the philosophers Moritz Schlick, Friedrich Waismann, and Rudolf Carnap who were members of the Circle. In the United States, he was a professor of philosophy and psychology at the University of Iowa.

Hans Reichenbach

Hans Reichenbach (September 26, 1891 – April 9, 1953) was a leading philosopher of science, educator, and proponent of logical empiricism. He was influential in the areas of science, education, and of logical empiricism. He founded the Gesellschaft für empirische Philosophie (Society for Empirical Philosophy) in Berlin in 1928, also known as the “Berlin Circle”. Carl Gustav Hempel, Richard von Mises, David Hilbert and Kurt Grelling all became members of the Berlin Circle. He authored The Rise of Scientific Philosophy. In 1930, Reichenbach and Rudolf Carnap became editors of the journal Erkenntnis (Knowledge). He also made lasting contributions to the study of empiricism based on a theory of probability; the logic and the philosophy of mathematics; space, time, and relativity theory; analysis of probabilistic reasoning; and quantum mechanics.

Index of philosophy of language articles

This is an index of articles in philosophy of language

A.P. Martinich


Adolph Stöhr

Alexis Kagame

Alfred Jules Ayer

Alphabet of human thought


Analytic-synthetic distinction


Andrea Bonomi

Applicative Universal Grammar

Archie J. Bahm

Arda Denkel


Artificial intelligence

Association for Logic, Language and Information

Avrum Stroll

Barry Loewer

Berlin Circle

Bertrand Russell

Bob Hale (philosopher)

Calculus ratiocinator

Carl Gustav Hempel

Ramsey sentence


Category mistake

Causal theory of reference

César Chesneau Dumarsais

Cheung Kam Ching

Circular definition

Claude Lévi-Strauss

Cognitive synonymy

Colloquial language

Computational humor


Concept and object

Conceptual metaphor

Context-sensitive grammar

Context principle


Contrast theory of meaning


Cooperative principle

Cora Diamond


Dagfinn Føllesdal

David Efird

David Kellogg Lewis

De dicto and de re



Descriptivist theory of names

Direct reference theory

Direction of fit

Discourse ethics

Disquotational principle

Donald Davidson (philosopher)

Donkey pronoun


Duns Scotus

Empty name

Engineered language

Enumerative definition


Ethics and Language

Eugen Rosenstock-Huessy

European Summer School in Logic, Language and Information


Extensional definition

F. H. Bradley

Family resemblance

Felicity conditions

Ferdinand Ebner

Failure to refer

Form of life (philosophy)

Franz Rosenzweig

Frege's Puzzle

Friedrich Waismann

Function and Concept

G. E. M. Anscombe

Gareth Evans (philosopher)

Genus–differentia definition

George Orwell

Gilbert Ryle

Gordon Park Baker

Gottlob Frege


Hans Kamp

Hector-Neri Castañeda

Henri Bergson

Ideal speech situation

Illocutionary act


Indeterminacy (philosophy)

Indeterminacy of translation


Indirect self-reference

Inferential role semantics

Ingeborg Bachmann


Intensional definition

Internalism and externalism

Interpretation (logic)

J. L. Austin

Jacques Bouveresse

James F. Conant

Jody Azzouni

John Etchemendy

John McDowell

Jonathan Bennett (philosopher)

Journal of Logic, Language and Information

Karl-Otto Apel

Katarzyna Jaszczolt

Keith Donnellan

Kent Bach

Kit Fine


Language and thought

Language of thought

Language, Truth, and Logic

Latitudinarianism (philosophy)

Lexical definition

Lexis (Aristotle)

Linguistic determinism

Linguistic relativity

Linguistic turn

Linguistics and Philosophy

List of philosophers of language

Logical atomism

Logical form

Logical positivism

Ludwig Wittgenstein

Marilyn Frye

Martian scientist

Max Black

Meaning (linguistics)

Meaning (non-linguistic)

Meaning (philosophy of language)

Meaning (semiotics)

Mediated reference theory

Meinong's jungle

Mental representation

Mental space


Metaphor in philosophy

Michael Devitt

Michael Dummett

Modal property


Modularity of mind

Moritz Schlick

Mumbo Jumbo (phrase)

Naming and Necessity

Nelson Goodman

New Foundations

Nino Cocchiarella

Noam Chomsky



Non-rigid designator


Norm (philosophy)

Object language

On Denoting

Ontological commitment

Operational definition

Ordinary language philosophy

Ostensive definition

Otto Neurath

P. F. Strawson

Paradigm-case argument


Paul Boghossian

Paul Grice

Performative contradiction

Performative text

Performative utterance

Persuasive definition

Peter Abelard

Peter Millican

Philosophical interpretation of classical physics

Philosophical Investigations

Philosophy and literature

Philosophy of language

Pirmin Stekeler-Weithofer

Plato's Problem

Port-Royal Grammar


Precising definition

Principle of charity

Principle of compositionality

Private language argument

Proper name (philosophy)




Radical translation

Rational reconstruction

Redundancy theory of truth


Relevance theory

Rhetoric of social intervention model

Richard von Mises

Rigid designator

Robert Brandom

Robert Maximilian de Gaynesford

Robert Stalnaker

Round square copula

Rudolf Carnap

S. Morris Engel

Saul Kripke

Scalar implicature

Scientific essentialism

Sebastian Shaumyan

Secondary reference


Semantic externalism

Semantic holism




Sense and reference

Sense and Sensibilia (Austin)



Singular term

Slingshot argument

Social semiotics

Speech act


Stanley Cavell

Statement (logic)

Stipulative definition


Supposition theory

Susan Stebbing




Symbol grounding


The Naturalization of Intentionality

Theoretical definition

Theory of descriptions

Þorsteinn Gylfason

Tractatus Logico-Philosophicus

Transparency (linguistic)

True name

Truth-conditional semantics

Truth-value link


Two Dogmas of Empiricism

Type physicalism

Universal grammar

Universal language

Universal pragmatics

Use–mention distinction


Verification theory


Vienna Circle

Virgil Aldrich

Walter Benjamin

Willard Van Orman Quine

William Alston

William C. Dowling

William Crathorn

Wittgenstein on Rules and Private Language

Word and Object

Word sense

Yehoshua Bar-Hillel

Zeno Vendler


Internal–external distinction

The internal–external distinction is a distinction used in philosophy to divide an ontology into two parts: an internal part consisting of a linguistic framework and observations related to that framework, and an external part concerning practical questions about the utility of that framework. This division was introduced by Rudolf Carnap in his work Empiricism, Semantics, and Ontology. It was subsequently criticized at length by Willard Van Orman Quine in a number of works, and was considered for some time to have been discredited. However, recently a number of authors have come to the support of some or another version of Carnap's approach.

Library of Living Philosophers

The Library of Living Philosophers is a series of books conceived of and started by Paul Arthur Schilpp in 1939; Schilpp remained editor until 1981. The series has since been edited by Lewis Edwin Hahn (1981-2001), Randall Auxier (2001-2013), and Douglas R. Anderson (2013-2015). The Library of Living Philosophers is currently edited by Sarah Beardsworth (2015-present). Each volume is devoted to a single living philosopher of note, and contains, alongside an "intellectual autobiography" of its subject and a complete bibliography, a collection of critical and interpretive essays by several dozen contemporary philosophers on aspects of the subject's work, with responses by the subject. The Library was originally conceived as a means by which a philosopher could reply to his or her interpreters while still alive, hopefully resolving endless philosophical disputes about what someone "really meant." While its success in this line has been questionable—a reply, after all, can stand just as much in need of interpretation as an original essay—the series has become a noted philosophical resource and the site of much significant contemporary argument.

The series was published by Northwestern University from its inception through 1949; by Tudor Publishing Co. from 1952 to 1959; and since then by Open Court. The series is owned by Southern Illinois University Carbondale.

Subjects of the Library, to date, are:

John Dewey (1939)

George Santayana (1940)

Alfred North Whitehead (1941)

G. E. Moore (1942)

Bertrand Russell (1944)

Ernst Cassirer (1949)

Albert Einstein (1949)

Sarvepalli Radhakrishnan (1952)

Karl Jaspers (1957)

C. D. Broad (1959)

Rudolf Carnap (1963)

Martin Buber (1967)

C. I. Lewis (1968)

Karl Popper (1974)

Brand Blanshard (1980)

Jean-Paul Sartre (1981)

Gabriel Marcel (1984)

W. V. Quine (1986)

Georg Henrik von Wright (1989)

Charles Hartshorne (1991)

A. J. Ayer (1992)

Paul Ricoeur (1995)

Paul Weiss (1995)

Hans-Georg Gadamer (1997)

Roderick Chisholm (1997)

P. F. Strawson (1998)

Donald Davidson (1999)

Seyyed Hossein Nasr (2000)

Marjorie Grene (2002)

Jaakko Hintikka (2006)

Michael Dummett (2007)

Richard Rorty (2010)

Arthur Danto (2013)

Hilary Putnam (2015)

Umberto Eco (2017)Volumes projected on as of 2015: Martha C. Nussbaum, and Julia Kristeva

List of mathematical probabilists

See probabilism for the followers of such a theory in theology or philosophy.This list contains only probabilists in the sense of mathematicians specializing in probability theory.

This list is incomplete; please add to it.David Aldous (1952–)

Robert Azencott - Professor of Mathematics, University of Houston, Emeritus Professor, Ecole Normale Superieure, France

Thomas Bayes (1702–1761) - British mathematician and Presbyterian minister, known for Bayes' theorem

Gerard Ben-Arous - Courant Institute of Mathematical Sciences

Itai Benjamini

Jakob Bernoulli (1654–1705) - Switzerland, known for Bernoulli trials

Joseph Louis François Bertrand (1822–1900)

Abram Samoilovitch Besicovitch (1891–1970)

Patrick Billingsley (1925–2011)

Carlo Emilio Bonferroni (1892–1960)

Émile Borel (1871–1956)

Kai Lai Chung (1917–2009)

Erhan Cinlar

Harald Cramér (1893–1985)

Persi Diaconis (1945–)

Joseph Leo Doob (1910–2004)

Lester Dubins (1920–2010)

Eugene Dynkin (1924–2014)

Robert J. Elliott (1940–)

Paul Erdős (1913–1996)

Alison Etheridge

Steve Evans

William Feller (1906–1970)

Bruno de Finetti (1906–1985) - Italian probabilist and statistician

Geoffrey Grimmett (1950–)

Alice Guionnet

Ian Hacking (1936–)

Paul Halmos (1916–2006)

Joseph Halpern

David Heath

Wassily Hoeffding (1914–1991)

Kiyoshi Itō (1915–2008)

Edwin Thompson Jaynes (1922–1998)

Mark Kac (1914–1984)

Olav Kallenberg

Rudolf E. Kálmán (1930–2016)

Samuel Karlin (1924–2007)

David George Kendall (1918–2007)

Richard Kenyon - Brown University

Harry Kesten (1931–)

John Maynard Keynes (1883–1946) - best known for his pioneering work in economics

Aleksandr Khinchin (1894–1959)

Andrey Kolmogorov (1903–1987)

Pierre-Simon Laplace (1749–1827)

Gregory Lawler

Lucien Le Cam (1924–2000)

Jean-François Le Gall

Paul Lévy (1886–1971)

Jarl Waldemar Lindeberg (1876–1932)

Andrey Markov (1856–1922)

Stefan Mazurkiewicz (1888–1945)

Henry McKean (1930–)

Paul-André Meyer (1934–2003)

Richard von Mises (1883–1953)

Abraham de Moivre (1667–1754)

Octav Onicescu (1892–1983)

K. R. Parthasarathy

Blaise Pascal (1623–1662)

Charles E. M. Pearce (1940–)

Judea Pearl (1936–)

Yuval Peres

Edwin A. Perkins

Siméon Denis Poisson (1781–1840)

Yuri Vasilevich Prokhorov (1929–)

Frank P. Ramsey (1903–1930)

Alfréd Rényi (1921–1970)

Oded Schramm (1961–2008)

Romano Scozzafava

Scott Sheffield

Albert Shiryaev (1934–)

Yakov Sinai (1935–)

Ray Solomonoff (1926–2009)

Frank Spitzer (1926–1992)

Ruslan L. Stratonovich (1930–1997)

Daniel W. Stroock (1940–)

Alain-Sol Sznitman

Michel Talagrand (1952–)

Heinrich Emil Timerding (1873–1945)

Andrei Toom (1942–)

S. R. Srinivasa Varadhan (1940–) - 2007 Abel Prize laureate

Bálint Virág (1973–)

Wendelin Werner (1968–)

Norbert Wiener (1894–1964)

David Williams

Ofer Zeitouni (1960–) - Weizmann Institute

Rudolf Carnap (1891–1970) - one of the giants among twentieth-century philosophers (best known for confirmation probability)

Harold Jeffreys (1891–1989) - one of the giants within Bayesian statistics school

Richard Jeffrey (1926–2002) - best known for the philosophy of radical probabilism and Jeffrey conditioning

Terence Tao

Richard M. Dudley

William Timothy Gowers

Bálint Tóth

List of philosophers of language

This is a list of philosophers of language.

Virgil Aldrich

William Alston

G. E. M. Anscombe

Karl-Otto Apel


J. L. Austin

Alfred Jules Ayer

Joxe Azurmendi

Jody Azzouni

Kent Bach

Ingeborg Bachmann

Archie J. Bahm

Yehoshua Bar-Hillel

Walter Benjamin

Jonathan Bennett

Henri Bergson

Max Black

Paul Boghossian

Andrea Bonomi

Jacques Bouveresse

F. H. Bradley

Robert Brandom

Berit Brogaard

Herman Cappelen

Rudolf Carnap

Hector-Neri Castañeda

Stanley Cavell

David Chalmers

Cheung Kam Ching

Noam Chomsky

Alonzo Church

Nino Cocchiarella

James F. Conant

William Crathorn

Donald Davidson

Arda Denkel

Michael Devitt

Keith Donnellan

William C. Dowling

César Chesneau Dumarsais

Michael Dummett

David Efird

S. Morris Engel

John Etchemendy

Gareth Evans

Kit Fine

Dagfinn Føllesdal

Gottlob Frege

Marilyn Frye

Robert Maximilian de Gaynesford

Peter Geach

Alexander George

Allan Gibbard

Gongsun Long

Nelson Goodman

Paul Grice

Jeroen Groenendijk

Samuel Guttenplan

Þorsteinn Gylfason

Susan Haack

Jürgen Habermas

Peter Hacker

Ian Hacking

Axel Hägerström

Bob Hale

Oswald Hanfling

Gilbert Harman

John Hawthorne

Jaakko Hintikka

William Hirstein

Richard Hönigswald

Jennifer Hornsby

Paul Horwich

Wilhelm von Humboldt

Carrie Ichikawa Jenkins

David Kaplan

Jerrold Katz

Saul Kripke

Mark Lance

Stephen Laurence

Ernest Lepore

David Kellogg Lewis

John Locke

Béatrice Longuenesse

Paul Lorenzen

William Lycan

John McDowell

Colin McGinn

Merab Mamardashvili

Ruth Barcan Marcus

José Medina

Maurice Merleau-Ponty

John Stuart Mill

Ruth Millikan

Richard Montague

Charles W. Morris

Adam Morton

Stephen Neale

William of Ockham

Jesús Padilla Gálvez

Peter Pagin

L.A. Paul

Charles Sanders Peirce

Carlo Penco

John Perry

Gualtiero Piccinini

Steven Pinker


Hilary Putnam

Willard Van Orman Quine

Adolf Reinach

Denise Riley

Richard Rorty


Jay Rosenberg

Bertrand Russell's views on philosophy

Bertrand Russell

Gilbert Ryle

Robert Rynasiewicz

Mark Sainsbury

Nathan Salmon

Stephen Schiffer

Duns Scotus

John Searle

Susanna Siegel

Brian Skyrms

Quentin Smith

Scott Soames

David Sosa

Robert Stalnaker

Jason Stanley

Jaun Elia

Stephen Yablo

P. F. Strawson

Alfred Tarski

Kenneth Allen Taylor

Ernst Tugendhat

Michael Tye

Zeno Vendler

Vācaspati Miśra

Friedrich Waismann

Brian Weatherson

Michael Williams

Timothy Williamson

John Wisdom

Ludwig Wittgenstein

Crispin Wright

Georg Henrik von Wright

Edward N. Zalta

Eddy Zemach

Paul Ziff

Dean Zimmerman

Logical atomism

Logical atomism is a philosophy that originated in the early 20th century with the development of analytic philosophy. Its principal exponent was the British philosopher Bertrand Russell. It is also widely held that the early work (the Tractatus and pre-Tractatus writings) of his Austrian-born pupil and colleague, Ludwig Wittgenstein, defend a version of logical atomism. Some philosophers in the Vienna Circle were also influenced by logical atomism. Rudolf Carnap was also deeply sympathetic to some of the philosophical aims of logical atomism. Gustav Bergmann also developed a form of logical atomism that focused on an ideal phenomalistic language, particularly in his discussions of J.O. Urmson's work on analysis.The name for this kind of theory was coined in March 1911 by Russell, in a work published in French titled "Le Réalisme analytique" (published in translation as "Analytic Realism" in Volume 6 of The Collected Papers of Bertrand Russell). Russell was developing and responding to what he called "logical holism"—i.e., the belief that the world operates in such a way that no part can be known without the whole being known first. This belief is commonly called monism, and Russell (and G. E. Moore) criticized the absolute idealism dominant then in Britain and exemplified in works of F. H. Bradley and J. M. E. McTaggart. Logical atomism is partly understood as a developed alternative to logical holism, or the "monistic logic" of Idealists, on which logical analysis is a kind of falsification.

The theory holds that the world consists of ultimate logical "facts" (or "atoms") that cannot be broken down any further. Having originally propounded this stance in his Tractatus Logico-Philosophicus, Wittgenstein rejected it in his later Philosophical Investigations (§§46–49, §81, §91).

Logical behaviorism

Logical behaviorism (also known as analytical behaviorism) is a theory of mind that mental concepts can be explained in terms of behavioral concepts.Logical behaviorism was first stated by the Vienna Circle, especially Rudolf Carnap. Other philosophers with sympathies for behaviorism included C. G. Hempel, Ludwig Wittgenstein, and W. V. O. Quine (1960). A more moderate form of analytical behaviorism was put forward by the Oxford philosopher Gilbert Ryle in his book The Concept of Mind (1949).

Logical positivism

Logical positivism and logical empiricism, which together formed neopositivism, was a movement in Western philosophy whose central thesis was verificationism, a theory of knowledge which asserted that only statements verifiable through empirical observation are meaningful. The movement flourished in the 1920s and 1930s in several European centers.

Efforts to convert philosophy to this new "scientific philosophy", shared with empirical sciences' best examples, such as Albert Einstein's general theory of relativity, sought to prevent confusion rooted in unclear language and unverifiable claims.The Berlin Circle and Vienna Circle—groups of philosophers, scientists, and mathematicians in Berlin and Vienna—propounded logical positivism, starting in the late 1920s.

Meaning and Necessity

Meaning and Necessity: A Study in Semantics and Modal Logic (1947; enlarged edition 1956) is a book about semantics and modal logic by the philosopher Rudolf Carnap. The book, in which Carnap discusses the nature of linguistic expressions, was a continuation of his previous work in semantics in Introduction to Semantics (1942) and Formalization of Logic (1943). Considered an important discussion of semantics, it was influential and provided a basis for further developments in modal logic.

Meaning postulate

In semantics, a meaning postulate is the notion that lexical items can be defined in terms of relations with other lexical items. The classic example (formulated by Rudolf Carnap) is: bachelor = unmarried male.

Meaning Postulate is a formula to express an aspect of the sense of a predicate. The formula is expressed with - so-called - connectives.

The used connectives are:

paraphrase ≡ "if and only if"

entailment → "if"

binary antonomy ~ "not"

Following examples will simplify this:

1. "If and only if X is a man, then X is a human being." In meaning postulate this would look like this:


2. "If X is a girl, then X is female." In meaning postulate this would look like this:


3. "X is not awake, therefore X is asleep." In meaning postulate this would look like this:


Scientific evidence

Scientific evidence is evidence which serves to either support or counter a scientific theory or hypothesis. Such evidence is expected to be empirical evidence and interpretation in accordance with scientific method. Standards for scientific evidence vary according to the field of inquiry, but the strength of scientific evidence is generally based on the results of statistical analysis and the strength of scientific controls.

Vienna Circle

The Vienna Circle (German: Wiener Kreis) of Logical Empiricism was a group of philosophers and scientists drawn from the natural and social sciences, logic and mathematics who met regularly from 1924 to 1936 at the University of Vienna, chaired by Moritz Schlick.

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