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logical positivism: Definition and Much More from Answers.com

Logical positivism grew from the discussions of 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.

Origins

The chief influences on the early logical positivists were the positivist 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 verification 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".^[1] 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. According to Neurath, not all the logical positivists liked the Tractatus; it was full of metaphysics.^[2]

Contemporary 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.^[3]

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^[4], and the positivists all shared somewhat Kantian views about the relationship between philosophy and science.^[5]

Basic tenets

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.

Perhaps the view for which the logical positivists are best known is the verifiability criterion of meaning, or verificationism. In one of its earlier and stronger formulations, this is the doctrine that a proposition is "cognitively meaningful" only if there is a finite procedure for conclusively determining whether it is true or false.^[6] An intended consequence of this view, for most logical positivists, is that metaphysical, theological, and ethical statements fall short of this criterion, and so are not cognitively meaningful.^[7] They distinguished cognitive from other varieties of meaningfulness (e.g. emotive, expressive, figurative), and most authors concede that the non-cognitive statements of the history of philosophy possess some other kind of meaningfulness. The positive characterization of cognitive meaningfulness varies from author to author. It has been described as the property of having a truth value, corresponding to a possible state of affairs, naming a proposition, or being intelligible or understandable in the sense in which scientific statements are intelligible or understandable.^[8]

Another characteristic feature of logical positivism is the commitment to "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.^[9] 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;^[10] sometimes these reductions took the form of allegedly analytic or a priori deductive relationships.^[11]. A number of publications over a period of thirty years would attempt to elucidate this concept.

Criticism and influences

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. ^{[citation needed]} 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, although Popper thought himself these could be deemed as verifiable^[12].

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. W. V. O. Quine criticized the distinction between analytic and synthetic statements and the reduction of meaningful statements to immediate experience. Work by 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.

Footnotes

^ "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
^ 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"
^ 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.
^ See the essays by Schlick, Carnap, and Neurath in Ayer's Logical Positivism.
^ Friedman, Michael, Reconsidering Logical Positivism. Cambridge, UK: Cambridge University Press, 1999.
^ For a classic survey of other versions of verificationism, see Hempel, Carl. "Problems and Changes in the Empiricist Criterion of Meaning." Revue Internationale de Philosophie 41 (1950), pp 41-63.
^ For the classic expression of this view, see Carnap, op. cit. 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.
^ Examples of these different views can be found in Scheffler's Anatomy of Inquiry, Ayer's Language, Truth, and Logic, Schlick's "Positivism and Realism" (rpt. in Sarkar (1996) and Ayer (1959)), and Carnap's Philosophy and Logical Syntax.
^ 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]
^ As in Carnap's (1928) Logical Structure of the World.
^ As in Carnap's Testability and Meaning
^ Popper, K., The Logic of Scientific Discovery, chapter 13

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logical positivism: Definition and Much More from Answers.com

Origins

Basic tenets

Criticism and influences

Footnotes

Further reading

See also

People

Institutions

Other philosophical movements

External links

Articles by logical positivists

Articles on logical positivism

Articles on related philosophical topics