Logical positivism

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Logical positivism (later and more accurately called logical empiricism) is a school of philosophy that combines empiricism—the idea that observational evidence is indispensable for knowledge of the world we live in—with a version of rationalism—the idea that our knowledge includes a component that is not derived from observation.

A central tenet of logical positivism is that metaphysical, theological, and ethical sentences are "cognitively meaningless,"[1] and serve merely to express the feelings or desires of a speaker. Only mathematical, logical and scientific statements are literally meaningful, or have truth values.

Logical positivism grew from the discussions of the Moritz Schlick's Vienna Circle and Hans Reichenbach's Berlin Circle in the 1920s and 1930s. The movement is known for its espousal of verificationism, its admiration for science and technical rigor, and its commitment to the analytic-synthetic distinction. The logical positivists agreed that there are no synthetic a priori propositions, though they disagreed with earlier positivists, such as Ernst Mach, who held that the a priori had no place in science.

Contents

[edit] The Origins of Logical Positivism

The chief influences on the early logical positivists were Ernst Mach and Ludwig Wittgenstein.

Mach's influence is most apparent in the logical positivists' persistent concern with metaphysics, the unity of science, and the interpretation of the theoretical terms of science, as well as the doctrines of reductionism and phenomenalism, later abandoned by many positivists.

Wittgenstein's Tractatus was a text of great importance for the positivists. The use of the tools of modern logic for linguistic reform, the conception of philosophy as a "critique of language," and the possibility of drawing a theoretically principled distinction between intelligible and nonsensical discourse were all appealing to the logical positivists. Many positivists adopted a correspondence theory of truth similar to that of the Tractatus, although some, like Otto Neurath, preferred a form of coherentism. Wittgenstein's influence is further evident in certain formulations of the verifiability principle. Compare, for example, Proposition 4.024 of the Tractatus, where Wittgenstein asserts that we understand a proposition when we know what happens if it is true, with Schlick's assertion that "To state the circumstances under which a proposition is true is the same as stating its meaning".[2] The tractarian doctrine that the truths of logic are tautologies was widely held among the logical positivists. Wittgenstein also influenced the logical positivists' interpretation of probability. It should be noted that not all logical positivists' reactions to the Tractatus were positive; according to Neurath, it was full of metaphysics.[3]

Recent developments in logic and the foundations of mathematics, especially Russell and Whitehead's monumental Principia Mathematica, impressed the more mathematically minded logical positivists such as Hans Hahn and Rudolf Carnap. "Language-planning" and syntactical techniques derived from these developments were used to defend logicism in the philosophy of mathematics and various reductionist theses. Russell's theory of types was employed to explosive effect in Carnap's early anti-metaphysical polemics.[4]

Immanuel Kant was something of a punching bag in many of the logical positivists' early debates, but his influence shows through. His doctrine of synthetic a priori truths was the view to overthrow, and his notion of the thing in itself commanded its fair share of attention. More positively, Kantian views about the nature of physical objects pervade the "protocol sentence" debate[5], and the positivists all shared somewhat Kantian views about the relationship between philosophy and science.[6]

[edit] The Basic Tenets of Logical Positivism

Although the logical positivists held a wide range of beliefs on many matters, they were all interested in science and skeptical of theology and metaphysics. Early on, most logical positivists believed that all knowledge is based on logical inference from simple "protocol sentences" grounded in observable facts. Many logical positivists supported forms of materialism, philosophical naturalism, and empiricism.

Logical positivism is perhaps best known for the verifiability criterion of meaning, which asserts that a statement is meaningful if and only if it is empirically verifiable. One intended consequence of the verification criterion is that all non-empirical forms of discourse, including ethics and aesthetics, are not "literally" or "cognitively" meaningful, and thus belong to "metaphysics".

[edit] Unified Science

An important objective pursued by logical positivism is "unified science"; that is, the development of a common language or, in Neurath's phrase, a "universal slang" in which all scientific propositions can be expressed.[7] The adequacy of proposals or fragments of proposals for such a language was often asserted on the basis of various "reductions" or "explications" of the terms of one special science to the terms of another, putatively more fundamental one. Sometimes these reductions took the form of set-theoretic manipulations of a handful of logically primitive concepts;[8] sometimes these reductions took the form of allegedly analytic or a priori deductive relationships.[9]. A number of publications over a period of thirty years would attempt to elucidate this concept.

[edit] Einheitswissenschaft (Unified Science)

The Vienna Circle published a collection called Einheitswissenschaft (Unified Science)—edited by Rudolf Carnap, Philipp Frank, Hans Hahn, Otto Neurath, Jorgen Jorgensen (after Hahn's death) and Charles Morris—the aim of which was to present a unified vision of science. The collection was dismissed, after the publication of several monographies, because of the problems arising from World War II. The list of philosophers and scientists who contributed to these works is impressive. The complete list of contributors is given here for the historical record.

Einheitswissenschaft (Unified Science), edited by Carnap, Frank, Hahn, Neurath, Jorgensen (after Hahn's death), and Morris (from 1938):

These works are translated in Unified Science: The Vienna Circle Monograph Series, originally edited by Otto Neurath:, Kluwer, 1987.

[edit] International Encyclopedia of Unified Science

In 1938 the publication of the International Encyclopedia of Unified Science started under the auspice of logical positivists. It was an ambitious project, and never completed. Only the first section, Foundations of the Unity of Sciences, was published; it contained two volumes, for a total of twenty monographs published from 1938 to 1969:

  • Otto Neurath, Niels Bohr, John Dewey, Bertrand Russell, Rudolf Carnap, Charles Morris, Encyclopedia and unified science, 1938, vol.1 n.1
  • Charles Morris, Foundations of the theory of signs, 1938, vol.1 n.2
  • Victor Lenzen, Procedures of empirical sciences, 1938, vol.1 n.5
  • Rudolf Carnap, Foundations of logic and mathematics, 1939, vol.1 n.3
  • Leonard Bloomfield, Linguistic aspects of science, 1939, vol.1 n.4
  • Ernest Nagel, Principles of the theory of probability, 1939, vol.1 n.6
  • John Dewey, Theory of valuation, 1939, vol.2 n.4
  • Giorgio De Santillana and Egdard Zilsel, The development of rationalism and empiricism, 1941, vol.2 n.8
  • Otto Neurath, Foundations of social sciences, 1944, vol.2 n.1
  • Joseph Henri Woodger, The technique of theory construction, 1949, vol.2 n.5
  • Philipp Frank, Foundations of physics, 1946, vol.1 n.7
  • Erwin Frinlay-Freundlich, Cosmology, 1951, vol.1 n.8
  • Jorgen Jorgensen, The development of logical empiricism, 1951, vol.2 n.9
  • Egon Brunswik, The conceptual framework of psychology, 1952, vol.1 n.10
  • Carl Hempel, Fundamentals of concept formation in empirical science, 1952, vol.2 n.7
  • Felix Mainx, Foundations of biology, 1955, vol.1 n.9
  • Abraham Edel, Science and the structure of ethics, 1961, vol.2 n.3
  • Thomas Kuhn, The structure of scientific revolutions, 1962, vol.2 n.2
  • Gherard Tintner, Methodology of mathematical economics and econometrics, 1968, vol.2 n.6
  • Herbert Feigl and Charles Morris, Bibliography and index, 1969, vol.2 n.10

Perhaps the most famous work published in the International Encyclopedia of Unified Science is Thomas Kuhn's The Structure of Scientific Revolutions. However, every entry in the encyclopedia is of substantial scientific and philosophical value.

[edit] Monographs on the Scientific World-Conception

A third collection was published by the Vienna Circle from 1928 to 1937. This collection was entitled Schriften zur wissenschaftlichen Weltauffassung (Monographs on the Scientific World-Conception), and was edited by Schlick and Frank. Scientists and philosophers such as Karl Popper contributed. The contributors and monographs were:

  • Richard von Mises, Wahrscheinlichkeit, Statistik und Wahrheit, 1928 (Probability, Statistics, and Truth, New York: MacMillan Company, 1939)
  • Rudolf Carnap, Abriss der Logistik, 1929
  • Moritz Schlick, Fragen der Ethik, 1930 (Problems of Ethics, New York: Prentice-Hall, 1939)
  • Otto Neurath, Empirische Soziologie, 1931
  • Philipp Frank, Das Kausalgesetz und seine Grenzen, 1932 (The Law of Causality and its Limits, Dordrecht; Boston: Kluwer, 1997)
  • Otto Kant, Zur Biologie der Ethik, 1932
  • Rudolf Carnap, Logische Syntax der Sprache, 1934 (The Logical Syntax of Language, New York: Humanities, 1937)
  • Karl Popper, Logik der Forschung, 1934 (The Logic of Scientific Discovery, New York: Basic Books, 1959)
  • Josef Schächeter, Prolegomena zu einer kritischen Grammatik, 1935 (Prolegomena to a Critical Grammar, Dordrecht; Boston: D. Reidel Pub. Co., 1973)
  • Victor Kraft, Die Grundlagen einer wissenschaftliche Wertlehre, 1937 (Foundations for a Scientific Analysis of Value, Dordrecht; Boston: D. Reidel Pub. Co., 1981)

[edit] Philosophers associated with logical positivism

There is an extensive list of philosophers who are associated to some degree with logical positivism.

[edit] The Vienna Circle

[edit] Germany and the Berlin Circle

In Germany, members of the Berlin Circle contributed in an essential way to the development of logical positivism:

[edit] Scandinavia

  • As early as 1930 Scandinavian philosophers were interested in logical positivism. Two of them, Swedish Åke Petzäll and Finnish Eino Kaila, employed for the first time the expression "logical neopositivism" for denoting the new philosophical movements (A. Petzäll, Der logistische Neupositivismus, 1930; and E. Kaila, "Der logistische Neupositivismus" in Annales Universitatis Aboensis, 1930). Petzäll was mainly influenced by the Vienna Circle and in 1930 or 1931 he went to Vienna, where he took part in theVienna Circle's meetings. Later he founded a new journal, Theoria, published in Göteborg; in that journal Hempel published his very first description of the paradoxes of confirmation (Le problème de la vérité, 1937). Eino Kaila published in 1939 a work pervaded by the principles of logical positivism (The human knowledge, in Finnish). He taught philosophy at the University of Helsinki. Among his students was Georg Henrik von Wright, who published a study about logical positivism (The Logical Empiricism, 1943, in Finnish). Wright contributed to the development of modal logic and deontic logic. Finn Jaakko Hintikka, who had Wright as a teacher, pursued Carnap's studies on inductive logic. Hintikka's article "A two-dimensional continuum of inductive methods" in Aspects of inductive logic (eds. J. Hintikka and P. Suppes, 1966), extended the methods Carnap used in The Continuum of Inductive Methods, 1952.
  • Danish philosopher Jorgen Jorgensen very actively collaborated with neopositivists. After Hans Hahn's death in 1934, Jørgensen became an editor of the Vienna Circle's series Unified Science; later he collaborated on the International Encyclopedia of Unified Science, to which he contributed the 1951 essay The Development of Logical Empiricism.

[edit] United Kingdom

  • English philosopher Alfred Jules Ayer played an important role in the spread of logical positivism. His 1936 work Language, Truth and Logic gained immediate success. In that book, he completely accepted both the verifiability principle and the distinction between analytic and synthetic statements; hence he asserted that metaphysical sentences are meaningless.

[edit] Poland

  • Logical positivism had extensive contacts with the group of Polish logicians who developed several branches of contemporary logic. Polish philosophy was greatly influenced by Kazimierz Twardowski, who studied at the University of Vienna and taught at Lwow; he is the founder of Polish analytic philosophy. He taught several Polish philosophers and logicians. Among them were:
  • The Polish logician Alfred Tarski, who developed the theory of semantics in formal language, took part in the congresses on scientific philosophy organized by the Vienna and Berlin Circles; he greatly influenced Carnap's philosophy of language. Carnap was interested in logical syntax but, after the publication of Tarski's works, he turned to semantics.

[edit] Reactions to Logical Positivism

Early critics of logical positivism said that its fundamental tenets could not themselves be formulated in a way that was clearly consistent. The verifiability criterion of meaning did not seem verifiable; but neither was it simply a logical tautology, since it had implications for the practice of science and the empirical truth of other statements. This presented severe problems for the logical consistency of the theory. Another problem was that, while positive existential claims ("there is at least one human being") and negative universals ("not all ravens are black") allow for clear methods of verification (find a human or a non-black raven), negative existential claims and positive universal claims do not allow for verification.

Universal claims could apparently never be verified: How can you tell that all ravens are black, unless you've hunted down every raven ever, including those in the past and future? This led to a great deal of work on induction, probability, and "confirmation", which combined verification and falsification.

Karl Popper, a well-known critic of logical positivism, published the book Logik der Forschung in 1934 (translated by himself as The Logic of Scientific Discovery published 1959). In it he presented an influential alternative to the verifiability criterion of meaning, defining scientific statements in terms of falsifiability. First, though, Popper's concern was not with distinguishing meaningful from meaningless statements, but distinguishing "scientific" from "metaphysical" statements. He did not hold that metaphysical statements must be meaningless; neither did he hold that a statement that in one century was "metaphysical" while unfalsifiable (like the ancient Greek philosophy about atoms), could not in another century become "falsifiable" and thus "scientific". About psychoanalysis he thought something similar: in his day it offered no method for falsification, and thus was not falsifiable and not scientific. However, he did not exclude it being meaningful, nor did he say psychoanalysts were necessarily "wrong" (it only couldn't be proven either way: that would have meant it was falsifiable), nor did he exclude that one day psychoanalysis could evolve into something falsifiable, and thus "scientific". He was, in general, more concerned with scientific practice than with the logical issues that troubled the positivists. Second, although Popper's philosophy of science enjoyed great popularity for some years, if his criterion is construed as an answer to the question the positivists were asking, it turns out to fail in exactly parallel ways. Negative existential claims ("there are no unicorns") and positive universals ("all ravens are black") can be falsified, but positive existential and negative universal claims cannot.

Logical positivists' response to the first criticism is that logical positivism is a philosophy of science, not an axiomatic system that can prove its own consistency (see Gödel's incompleteness theorem). Secondly, a theory of language and mathematical logic were created to answer what it really means to make statements like "all ravens are black".

A response to the second criticism was provided by A. J. Ayer in Language, Truth and Logic, in which he sets out the distinction between "strong" and "weak" verification. "A proposition is said to be verifiable, in the strong sense of the term, if, and only if, its truth could be conclusively established by experience." (Ayer 1946:50) It is this sense of verifiable that causes the problem of verification with negative existential claims and positive universal claims. However, the weak sense of verification states that a proposition is "verifiable... if it is possible for experience to render it probable" (ibid.). After establishing this distinction, Ayer goes on to claim that "no proposition, other than a tautology, can possibly be anything more than a probable hypothesis" (Ayer 1946:51), and therefore can only be subject to weak verification. This defense was controversial among logical positivists, some of whom stuck to strong verification, and claimed that general propositions were indeed nonsense.

Subsequent philosophy of science tends to make use of certain aspects of both of these approaches. Work by W. V. O. Quine and Thomas Kuhn has convinced many that it is not possible to provide truth conditions for science independent of its historical paradigm. But even this criticism was not unknown to the logical positivists: Otto Neurath compared science to a boat which we must rebuild on the open sea.

Logical positivism was essential to the development of early analytic philosophy. It was disseminated throughout the European continent and, later, in American universities by the members of the Vienna Circle. A.J. Ayer is considered responsible for the spread of logical positivism to Britain. The term subsequently came to be almost interchangeable with "analytic philosophy" in the first half of the twentieth century. Logical positivism was immensely influential in the philosophy of language and represented the dominant philosophy of science between World War I and the Cold War. Many subsequent commentators on "logical positivism" have attributed to its proponents a greater unity of purpose and creed than they actually shared, overlooking the complex disagreements among the logical positivists themselves.

[edit] Footnotes

  1. ^ For the classic expression of this view, see Carnap, Rudolf. "The Elimination Of Metaphysics Through Logical Analysis of Language." Erkenntnis 2 (1932). Rpt. in Logical Positivism. Ed. Alfred Jules Ayer. New York: Free Press, 1959. 60-81. Moritz Schlick, a key figure in the logical positivist movement, did not believe ethical (or aesthetic) sentences to be cognitively meaningless. See Schlick, Moritz. "The Future Of Philosophy." The Linguistic Turn. Ed. Richard Rorty. Chicago: University of Chicago Press, 1992. 43-53.
  2. ^ "Positivismus und Realismus", Erkenntnis 3:1-31, English trans. in Sarkar, Sahotra (ed.) Logical Empiricism at its Peak: Schlick, Carnap, and Neurath. New York: Garland Pub., 1996, p. 38
  3. ^ For a very informative and somewhat cute summary of the effect the Tractatus had on the leading logical positivists, see the Entwicklung der Thesen des "Wiener Kreises"
  4. ^ Carnap, op. cit.
  5. ^ See the essays by Carnap and Neurath in Ayer's Logical Positivism.
  6. ^ Friedman, Michael, Reconsidering Logical Positivism. Cambridge, UK: Cambridge University Press, 1999.
  7. ^ For a thorough consideration of what the thesis of the unity of science amounts to, see Frost-Arnold, Gregory, "The Large-Scale Structure of Logical Empiricism: Unity of Science and the Rejection of Metaphysics" at [1]
  8. ^ As in Carnap's (1928) Logical Structure of the World.
  9. ^ As in Carnap's Testability and Meaning

[edit] Further Reading

  • Achinstein, Peter and Barker, Stephen F. The Legacy of Logical Positivism: Studies in the Philosophy of Science. Baltimore: Johns Hopkins Press, 1969.
  • Ayer, Alfred Jules. Logical Positivism. Glencoe, Ill: Free Press, 1959.
  • Barone, Francesco. Il neopositivismo logico. Roma Bari: Laterza, 1986.
  • Bergmann, Gustav. The Metaphysics of Logical Positivism. New York: Longmans Green, 1954.
  • Cirera, Ramon. Carnap and the Vienna Circle: Empiricism and Logical Syntax. Atlanta, GA: Rodopi, 1994.
  • Edmonds, David & Eidinow, John; Wittgenstein's Poker, ISBN 0-06-621244-8
  • Friedman, Michael. Reconsidering Logical Positivism. Cambridge, UK: Cambridge University Press, 1999
  • Gadol, Eugene T. Rationality and Science: A Memorial Volume for Moritz Schlick in Celebration of the Centennial of his Birth. Wien: Springer, 1982.
  • Geymonat, Ludovico. La nuova filosofia della natura in Germania. Torino, 1934.
  • Giere, Ronald N. and Richardson, Alan W. Origins of Logical Empiricism. Minneapolis: University of Minnesota Press, 1997.
  • Hanfling, Oswald. Logical Positivism. Oxford: B. Blackwell, 1981.
  • Jangam, R. T. Logical Positivism and Politics. Delhi: Sterling Publishers, 1970.
  • Janik, Allan and Toulmin, Stephen. Wittgenstein's Vienna. London: Weidenfeld and Nicolson, 1973.
  • Kraft, Victor. The Vienna Circle: The Origin of Neo-positivism, a Chapter in the History of Recent Philosophy. New York: Greenwood Press, 1953.
  • McGuinness, Brian. Wittgenstein and the Vienna Circle: Conversations Recorded by Friedrich Waismann. Trans. by Joachim Schulte and Brian McGuinness. New York: Barnes & Noble Books, 1979.
  • Mises von, Richard. Positivism: A Study in Human Understanding. Cambridge: Harvard University Press, 1951.
  • Parrini, Paolo. Empirismo logico e convenzionalismo: saggio di storia della filosofia della scienza. Milano: F. Angeli, 1983.
  • Parrini, Paolo; Salmon, Wesley C.; Salmon, Merrilee H. (ed.) Logical Empiricism - Historical and Contemporary Perspectives, Pittsburgh: University of Pittsburgh Press, 2003.
  • Reisch, George. How the Cold War Transformed Philosophy of Science : To the Icy Slopes of Logic. New York: Cambridge University Press, 2005.
  • Rescher, Nicholas. The Heritage of Logical Positivism. Lanham, MD: University Press of America, 1985.
  • Salmon, Wesley and Wolters, Gereon (ed.), Logic, Language, and the Structure of Scientific Theories: Proceedings of the Carnap-Reichenbach Centennial, University of Konstanz, 21-24 May 1991, Pittsburgh: University of Pittsburgh Press, 1994.
  • Sarkar, Sahotra. The Emergence of Logical Empiricism: From 1900 to the Vienna Circle. New York: Garland Publishing, 1996.
  • Sarkar, Sahotra. Logical Empiricism at its Peak: Schlick, Carnap, and Neurath. New York: Garland Pub., 1996.
  • Sarkar, Sahotra. Logical Empiricism and the Special Sciences: Reichenbach, Feigl, and Nagel. New York: Garland Pub., 1996.
  • Sarkar, Sahotra. Decline and Obsolescence of Logical Empiricism: Carnap vs. Quine and the Critics. New York: Garland Pub., 1996.
  • Sarkar, Sahotra. The Legacy of the Vienna Circle: Modern Reappraisals. New York: Garland Pub., 1996.
  • Spohn, Wolfgang (ed.), Erkenntnis Orientated: A Centennial Volume for Rudolf Carnap and Hans Reichenbach, Boston: Kluwer Academic Publishers, 1991.

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