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Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, was a movement in
Western philosophy Western philosophy encompasses the philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical or mental reality ...
whose central thesis was the
verification principle Verificationism, also known as the verification principle or the verifiability criterion of meaning, is the philosophical doctrine which maintains that only statements that are empiricism, empirically verifiable (i.e. verifiable through the senses) ...
(also known as the verifiability criterion of meaning). This
theory of knowledge Epistemology (; ) is the branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of mind, ...

theory of knowledge
asserted that only statements verifiable through direct observation or logical proof are meaningful in terms of conveying truth value, information or factual content. Starting in the late 1920s, groups of philosophers, scientists, and mathematicians formed the
Berlin Circle The Berlin Circle (german: die Berliner Gruppe) was a group that maintained logical empiricist Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, was a movement in Western philosophy wh ...
and the
Vienna Circle The Vienna Circle (german: Wiener Kreis) of Logical Empiricism was a group of philosophers and scientists drawn from the Natural science, natural and Social Sciences, social sciences, logic and mathematics who met regularly from 1924 to 1936 at th ...
, which, in these two cities, would propound the ideas of logical positivism. Flourishing in several European centres through the 1930s, the movement sought to prevent confusion rooted in unclear language and unverifiable claims by converting philosophy into "scientific philosophy", which, according to the logical positivists, ought to share the bases and structures of
empirical sciences Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in the form of Testability, testable explanations and predictions about the u ...
' best examples, such as Albert Einstein's
general theory of relativity General relativity, also known as the general theory of relativity, is the differential geometry, geometric scientific theory, theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern ph ...
. Despite its ambition to overhaul philosophy by studying and mimicking the extant conduct of empirical science, logical positivism became erroneously stereotyped as a movement to regulate the scientific process and to place strict standards on it. After World War II, the movement shifted to a milder variant, logical empiricism, led mainly by
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
, who, during the rise of Nazism, had immigrated to the United States. In the ensuing years, the movement's central premises, still unresolved, were heavily criticised by leading philosophers, particularly
Willard van Orman Quine Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician Logic (from Greek: grc, λογική, label=none, lit=possessed of reason Reason is the capacity of ...
and
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British , and . One of the 20th century's most influential , Popper is known for his rejection of the classical views on the in favour of . According to Popper, a ...

Karl Popper
, and even, within the movement itself, by Hempel. The 1962 publication of
Thomas Kuhn Thomas Samuel Kuhn (; July 18, 1922 – June 17, 1996) was an American whose 1962 book ' was influential in both academic and popular circles, introducing the term ', which has since become an English-language idiom. Kuhn made several cla ...
's landmark book ''
The Structure of Scientific Revolutions ''The Structure of Scientific Revolutions'' (1962; second edition 1970; third edition 1996; fourth edition 2012) is a book about the history of science The history of science covers the development of science Science (from the Latin wo ...
'' dramatically shifted academic philosophy's focus. In 1967 philosopher
John Passmore John Passmore AC (9 September 1914 – 25 July 2004) was an Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian contin ...
pronounced logical positivism "dead, or as dead as a philosophical movement ever becomes".Passmore, John. 'Logical Positivism', ''The Encyclopedia of Philosophy'', Paul Edwards (ed.). New York: Macmillan, 1967, 1st edition
/ref>


Origins

Logical positivists picked from Ludwig Wittgenstein's early philosophy of language the verifiability principle or criterion of meaningfulness. As in
Ernst Mach Ernst Waldfried Josef Wenzel Mach (; ; 18 February 1838 – 19 February 1916) was an Austrian physicist and philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , t ...

Ernst Mach
's
phenomenalism Phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in space. In particular ...
, whereby the mind knows only actual or potential sensory experience, verificationists took all sciences' basic content to be only sensory experience. And some influence came from
Percy Bridgman The English surname Percy, first taken by the House of Percy File:Modern arms of Percy.svg, 200px, Arms of Percy ''modern'': ''Or, a lion rampant azure'', as shown on the seal of Henry de Percy, 1st Baron Percy (d.1314) affixed to the Barons' ...
's musings that others proclaimed as
operationalism In research design, especially in psychology Psychology is the science of mind and behavior. Psychology includes the study of consciousness, conscious and Unconscious mind, unconscious phenomena, as well as feeling and thought. It is an ac ...
, whereby a physical theory is understood by what laboratory procedures scientists perform to test its predictions. In
verificationism Verificationism, also known as the verification principle or the verifiability criterion of meaning, is the philosophical doctrine which maintains that only statements that are empirically verifiable (i.e. verifiable through the sense Sense relate ...
, only the ''verifiable'' was scientific, and thus meaningful (or ''cognitively meaningful''), whereas the unverifiable, being unscientific, were meaningless "pseudostatements" (just ''emotively meaningful''). Unscientific discourse, as in ethics and metaphysics, would be unfit for discourse by philosophers, newly tasked to organize knowledge, not develop new knowledge.


Definitions

Logical positivism is sometimes stereotyped as forbidding talk of
unobservableAn unobservable (also called impalpable) is an entity whose existence, nature, properties, qualities or relations are not directly observable by humans. In philosophy of science Philosophy of science is a branch of philosophy concerned with th ...
s, such as microscopic entities or such notions as causality and general principles, but that is an exaggeration. Rather, most neopositivists viewed talk of unobservables as
metaphor A metaphor is a figure of speech A figure of speech or rhetorical figure is a word or phrase that entails an intentional deviation from ordinary language use in order to produce a rhetoric Rhetoric () is the Art (skill), art of ...
ical or elliptical: direct observations phrased abstractly or indirectly. So ''
theoretical term Ramsey sentences are formal logical reconstructions of theoretical s attempting to draw a line between science and metaphysics. A Ramsey sentence aims at rendering propositions containing non-observable theoretical terms (terms employed by a theore ...
s'' would garner meaning from ''
observational term Ramsey sentences are formal logical reconstructions of theoretical proposition In logic and linguistics, a proposition is the meaning of a declarative sentence (linguistics), sentence. In philosophy, "Meaning (philosophy), meaning" is understood t ...
s'' via ''correspondence rules'', and thereby ''theoretical laws'' would be reduced to ''empirical laws''. Via
Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell (18 May 1872 – 2 February 1970) was a British , , , , , , , , and .Stanford Encyclopedia of Philosophy"Bertrand Russell" 1 May 2003 Throughout his life, Russell considered himself a , a and ...
's
logicism In the philosophy of mathematics The philosophy of mathematics is the branch The branches and leaves of a tree. A branch ( or , ) or tree branch (sometimes referred to in botany Botany, also called , plant biology or phytology, is ...
, reducing mathematics to logic, physics' mathematical formulas would be converted to
symbolic logic Mathematical logic, also called formal logic, is a subfield of mathematics exploring the formal applications of logic to mathematics. It bears close connections to metamathematics, the foundations of mathematics, and theoretical computer science. ...
. Via Russell's
logical atomism Logical atomism is a philosophical view that originated in the early 20th century with the development of analytic philosophy Analytic philosophy is a branch and tradition of philosophy Philosophy (from , ) is the study of general and f ...
,
ordinary language Ordinary language philosophy is a philosophical methodology Philosophical method (or philosophical methodology) is the study of how to do philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those ...
would break into discrete units of meaning.
Rational reconstruction Rational reconstruction is a philosophy, philosophical term with several distinct meanings. It is found in the work of Jürgen Habermas and Imre Lakatos. Habermas For Habermas, rational reconstruction is a philosophy, philosophical and linguist ...
, then, would convert ordinary statements into standardized equivalents, all networked and united by a logical syntax. A scientific theory would be stated with its method of verification, whereby a logical calculus or empirical operation could
verify is the primary configuration file for the DOS and OS/2 operating systems. It is a special ASCII text file that contains user-accessible setup or configuration directives evaluated by the operating system's DOS BIOS (typically residing in IBMBIO.CO ...
its falsity or truth.


Development

In the late 1930s, logical positivists fled Germany and Austria for Britain and the United States. By then, many had replaced Mach's phenomenalism with
Otto Neurath Otto Karl Wilhelm Neurath (; 10 December 1882 – 22 December 1945) was an Austria Austria (, ; german: Österreich ), officially the Republic of Austria (german: Republik Österreich, links=no, ), is a landlocked Eastern Alps, East Alp ...

Otto Neurath
's
physicalism In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical reality Reality is the sum or aggregate of all that is ...
, whereby science's content is not actual or potential sensations, but instead is entities publicly observable.
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Krei ...
, who had sparked logical positivism in the Vienna Circle, had sought to replace ''verification'' with simply ''confirmation''. With
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
's close in 1945, logical positivism became milder, ''logical empiricism'', led largely by
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
, in America, who expounded the covering law model of scientific explanation. Logical positivism became a major underpinning of
analytic philosophy Analytic philosophy is a branch and tradition of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical reality ...
,Se
"Vienna Circle"
in ''Stanford Encyclopedia of Philosophy''.
and dominated philosophy in the
English-speaking world Speakers of English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become the Wo ...
, including
philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methodology, methods, and implications of science. The central questions of this study concern Demarcation problem, what qualifies as science, the reliability of s ...
, while influencing sciences, but especially social sciences, into the 1960s. Yet the movement failed to resolve its central problems, and its doctrines were increasingly criticized, most trenchantly by
Willard Van Orman Quine Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic philosophy, analytic tradition, recognized as "one of the most influential philosophers of the ...
, Norwood Hanson,
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as tho ...
,
Thomas Kuhn Thomas Samuel Kuhn (; July 18, 1922 – June 17, 1996) was an American whose 1962 book ' was influential in both academic and popular circles, introducing the term ', which has since become an English-language idiom. Kuhn made several cla ...
, and
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
.


Roots


Language

''
Tractatus Logico-Philosophicus The ''Tractatus Logico-Philosophicus'' (widely abbreviated and cited as TLP) is a book-length philosophical work by the Austrian philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of genera ...
'', by the young
Ludwig Wittgenstein Ludwig Josef Johann Wittgenstein ( ; ; 26 April 1889 – 29 April 1951) was an Austrian Austrian may refer to: * Austrians, someone from Austria or of Austrian descent ** Someone who is considered an Austrian citizen, see Austrian nationali ...

Ludwig Wittgenstein
, introduced the view of philosophy as "critique of language", offering the possibility of a theoretically principled distinction of intelligible versus nonsensical discourse. ''Tractatus'' adhered to a
correspondence theory of truth In metaphysics Metaphysics is the branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of ...
(versus a
coherence theory of truthIn epistemology Epistemology (; ) is the Outline of philosophy, branch of philosophy concerned with knowledge. Epistemologists study the nature, origin, and scope of knowledge, epistemic Justification (epistemology), justification, the Reason, ...
). Wittgenstein's influence also shows in some versions of the verifiability principle. In tractarian doctrine, truths of logic are tautologies, a view widely accepted by logical positivists who were also influenced by Wittgenstein's interpretation of
probability Probability is the branch of mathematics Mathematics (from Greek: ) includes the study of such topics as numbers (arithmetic and number theory), formulas and related structures (algebra), shapes and spaces in which they are contained ...

probability
although, according to Neurath, some logical positivists found ''Tractatus'' to contain too much metaphysics.


Logicism

Gottlob Frege Friedrich Ludwig Gottlob Frege (; ; 8 November 1848 – 26 July 1925) was a German philosopher, logician, and mathematician. He worked as a mathematics professor at the University of Jena, and is understood by many to be the father of analy ...
began the program of reducing mathematics to logic, continued it with
Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell (18 May 1872 – 2 February 1970) was a British , , , , , , , , and .Stanford Encyclopedia of Philosophy"Bertrand Russell" 1 May 2003 Throughout his life, Russell considered himself a , a and ...
, but lost interest in this
logicism In the philosophy of mathematics The philosophy of mathematics is the branch The branches and leaves of a tree. A branch ( or , ) or tree branch (sometimes referred to in botany Botany, also called , plant biology or phytology, is ...
, and Russell continued it with
Alfred North Whitehead Alfred North Whitehead (15 February 1861 – 30 December 1947) was an English mathematician A mathematician is someone who uses an extensive knowledge of mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of ...
in their ''
Principia Mathematica Image:Principia Mathematica 54-43.png, 500px, ✸54.43: "From this proposition it will follow, when arithmetical addition has been defined, that 1 + 1 = 2." – Volume I, 1st editionp. 379(p. 362 in 2nd edition; p. 360 in abridged v ...
'', inspiring some of the more mathematical logical positivists, such as Hans Hahn and
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Krei ...
. Carnap's early anti-metaphysical works employed Russell's
theory of types In mathematics, logic, and computer science, a type system is a formal system in which every term has a "type" which defines its meaning and the operations that may be performed on it. Type theory is the academic study of type systems. Some type t ...
. Carnap envisioned a universal language that could reconstruct mathematics and thereby encode physics.Jaako Hintikka, "Logicism", in Andrew D Irvine, ed, ''Philosophy of Mathematics'' (Burlington MA: North Holland, 2009),
pp. 283–84
Yet
Kurt Gödel Kurt Friedrich Gödel ( , ; April 28, 1906 – January 14, 1978) was a logician Logic is an interdisciplinary field which studies truth Truth is the property of being in accord with fact or reality.Merriam-Webster's Online Dict ...
's
incompleteness theorem Complete may refer to: Logic * Completeness (logic) * Complete theory, Completeness of a theory, the property of a theory that every formula in the theory's language or its negation is provable Mathematics * The completeness of the real numbers, ...
showed this impossible except in trivial cases, and
Alfred Tarski Alfred Tarski (; January 14, 1901 – October 26, 1983), born Alfred Teitelbaum,School of Mathematics and Statistics, University of St Andrews ''School of Mathematics and Statistics, University of St Andrews''. was a Polish-American logician ...
's undefinability theorem shattered all hopes of reducing mathematics to logic. Thus, a universal language failed to stem from Carnap's 1934 work ''Logische Syntax der Sprache'' (''Logical Syntax of Language''). Still, some logical positivists, including
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
, continued support of logicism.


Empiricism

In Germany, Hegelian metaphysics was a dominant movement, and Hegelian successors such as F H Bradley explained reality by postulating metaphysical entities lacking empirical basis, drawing reaction in the form of positivism.Frederick Suppe, "The positivist model of scientific theories", in ''Scientific Inquiry'', Robert Klee, ed, (New York: Oxford University Press, 1999), pp. 16–24. Starting in the late 19th century, there was a "back to Kant" movement.
Ernst Mach Ernst Waldfried Josef Wenzel Mach (; ; 18 February 1838 – 19 February 1916) was an Austrian physicist and philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , t ...

Ernst Mach
's positivism and
phenomenalism Phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in space. In particular ...
were a major influence.


Origins


Vienna

The
Vienna Circle The Vienna Circle (german: Wiener Kreis) of Logical Empiricism was a group of philosophers and scientists drawn from the Natural science, natural and Social Sciences, social sciences, logic and mathematics who met regularly from 1924 to 1936 at th ...
, gathering around
University of Vienna The University of Vienna (german: Universität Wien) is a public university, public research university located in Vienna, Austria. It was founded by Rudolf IV, Duke of Austria, Duke Rudolph IV in 1365 and is the oldest university in the Geograph ...
and Café Central, was led principally by
Moritz Schlick Friedrich Albert Moritz Schlick (; ; 14 April 1882 – 22 June 1936) was a Germany, German philosopher, physicist, and the founding father of logical positivism and the Vienna Circle. Early life and works Schlick was born in Berlin to a wealthy f ...
. Schlick had held a
neo-Kantian In late modern philosophy, late modern continental philosophy, neo-Kantianism (german: Neukantianismus) was a revival of the 18th-century philosophy of Immanuel Kant. More specifically, it was influenced by Arthur Schopenhauer's critique of the K ...
position, but later converted, via Carnap's 1928 book ''Der logische Aufbau der Welt'', that is, ''The Logical Structure of the World''. A 1929 pamphlet written by
Otto Neurath Otto Karl Wilhelm Neurath (; 10 December 1882 – 22 December 1945) was an Austria Austria (, ; german: Österreich ), officially the Republic of Austria (german: Republik Österreich, links=no, ), is a landlocked Eastern Alps, East Alp ...

Otto Neurath
, Hans Hahn, and
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Krei ...
summarized the Vienna Circle's positions. Another member of Vienna Circle to later prove very influential was
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
. A friendly but tenacious critic of the Circle was
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British , and . One of the 20th century's most influential , Popper is known for his rejection of the classical views on the in favour of . According to Popper, a ...

Karl Popper
, whom nicknamed the "Official Opposition".
Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Kreis) ...
and other
Vienna Circle The Vienna Circle (german: Wiener Kreis) of Logical Empiricism was a group of philosophers and scientists drawn from the Natural science, natural and Social Sciences, social sciences, logic and mathematics who met regularly from 1924 to 1936 at th ...
members, including Hahn and , saw need for a weaker criterion of meaningfulness than verifiability. A radical "left" wing—led by Neurath and Carnap—began the program of "liberalization of empiricism", and they also emphasized
fallibilism Broadly speaking, fallibilism (from Medieval Latin: ''fallibilis'', "liable to err") is the philosophical claim that no belief can have justification which guarantees the truth of the belief, or that no beliefs are certain. Not all fallibilis ...
and
pragmatics In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspect of language, as well as the m ...
, which latter Carnap even suggested as empiricism's basis. A conservative "right" wing—led by Schlick and Waismann—rejected both the liberalization of empiricism and the epistemological nonfoundationalism of a move from
phenomenalism Phenomenalism is the view that physical objects cannot justifiably be said to exist in themselves, but only as perceptual phenomena or sensory stimuli (e.g. redness, hardness, softness, sweetness, etc.) situated in time and in space. In particular ...
to
physicalism In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical reality Reality is the sum or aggregate of all that is ...
. As Neurath and somewhat Carnap posed science toward social reform, the split in Vienna Circle also reflected political views.


Berlin

The
Berlin Circle The Berlin Circle (german: die Berliner Gruppe) was a group that maintained logical empiricist Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, was a movement in Western philosophy wh ...
was led principally by
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 ''Gesell ...
.


Rivals

Both
Moritz Schlick Friedrich Albert Moritz Schlick (; ; 14 April 1882 – 22 June 1936) was a Germany, German philosopher, physicist, and the founding father of logical positivism and the Vienna Circle. Early life and works Schlick was born in Berlin to a wealthy f ...
and
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Krei ...
had been influenced by and sought to define logical positivism versus the neo-Kantianism of
Ernst Cassirer Ernst Alfred Cassirer (; ; July 28, 1874 – April 13, 1945) was a German philosopher A philosopher is someone who practices philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of ...

Ernst Cassirer
—the then leading figure of
Marburg school In late modern philosophy, late modern continental philosophy, neo-Kantianism (german: Neukantianismus) was a revival of the 18th-century philosophy of Immanuel Kant. More specifically, it was influenced by Arthur Schopenhauer's critique of the K ...
, so called—and against
Edmund Husserl , thesis1_title = Beiträge zur Variationsrechnung (Contributions to the Calculus of Variations) , thesis1_url = https://fedora.phaidra.univie.ac.at/fedora/get/o:58535/bdef:Book/view , thesis1_year = 1883 , thesis2_title ...

Edmund Husserl
's
phenomenology Phenomenology may refer to: * Empirical research, when used to describe measurement methods in some sciences * An empirical relationship or phenomenological model * Phenomenology (architecture), based on the experience of building materials and the ...
. Logical positivists especially opposed
Martin Heidegger Martin Heidegger (; ; 26 September 188926 May 1976) was a key German philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, ...
's obscure metaphysics, the epitome of what logical positivism rejected. In the early 1930s, Carnap debated Heidegger over "metaphysical pseudosentences".Friedman, ''Reconsidering Logical Positivism'' (Cambridge UP, 1999)
p. xii
Despite its revolutionary aims, logical positivism was but one view among many vying within Europe, and logical positivists initially spoke their language.


Export

As the movement's first emissary to the
New World The "New World" is a term for the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. 33: "[16c: from ...
,
Moritz Schlick Friedrich Albert Moritz Schlick (; ; 14 April 1882 – 22 June 1936) was a Germany, German philosopher, physicist, and the founding father of logical positivism and the Vienna Circle. Early life and works Schlick was born in Berlin to a wealthy f ...
visited Stanford University in 1929, yet otherwise remained in Vienna and was murdered in 1936 at the University of Vienna, University by a former student, Johann Nelböck, who was reportedly deranged. That year, a British attendee at some Vienna Circle meetings since 1933,
A. J. Ayer Sir Alfred Jules "Freddie" Ayer (; 29 October 1910 – 27 June 1989), usually cited as A. J. Ayer, was an English philosopher known for his promotion of logical positivism Logical positivism, later called logical empiricism, and both of ...
saw his ''
Language, Truth and Logic ''Language, Truth and Logic'' is a 1936 book about Meaning (philosophy of language), meaning by the philosopher A. J. Ayer, Alfred Jules Ayer, in which the author defines, explains, and argues for the verification principle of logical positivism, s ...
'', written in English, import logical positivism to the
English-speaking world Speakers of English English usually refers to: * English language English is a West Germanic languages, West Germanic language first spoken in History of Anglo-Saxon England, early medieval England, which has eventually become the Wo ...
. By then, the
Nazi Party The Nazi Party, officially the National Socialist German Workers' Party (german: Nationalsozialistische Deutsche Arbeiterpartei or NSDAP), was a far-right Far-right politics, also referred to as the extreme right or right-wing extremism, ...
's 1933 rise to power in Germany had triggered flight of intellectuals. In exile in England,
Otto Neurath Otto Karl Wilhelm Neurath (; 10 December 1882 – 22 December 1945) was an Austria Austria (, ; german: Österreich ), officially the Republic of Austria (german: Republik Österreich, links=no, ), is a landlocked Eastern Alps, East Alp ...

Otto Neurath
died in 1945.
Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Krei ...
,
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 ''Gesell ...
, and
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
—Carnap's
protégé Mentorship is the influence, guidance, or direction given by a mentor. Mentor is someone who teaches or gives help and advice to a less experienced and often younger person. In an organizational setting, a mentor influences the personal and pro ...
who had studied in
Berlin Berlin (; ) is the Capital city, capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3,769,495 inhabitants, as of 31 December 2019 makes it the List of cities in the European Union by ...

Berlin
with Reichenbach—settled permanently in America. Upon Germany's annexation of Austria in 1938, remaining logical positivists, many of whom were also Jewish, were targeted and continued flight. Logical positivism thus became dominant in the English-speaking world.


Principles


Analytic/synthetic gap

Concerning
reality Reality is the sum or aggregate of all that is real or existent within a system, as opposed to that which is only imaginary Imaginary may refer to: * Imaginary (sociology), a concept in sociology * The Imaginary (psychoanalysis), a concept by ...

reality
, the
necessary Necessary or necessity may refer to: * Need A need is something that is necessary Necessary or necessity may refer to: * Need ** An action somebody may feel they must do ** An important task or essential thing to do at a particular time or by ...
is a state true in all
possible worlds A possible world is a complete and consistent way the world is or could have been. They are widely used as a formal device in logic Logic is an interdisciplinary field which studies truth and reasoning. Informal logic seeks to characterize ...
—mere
logical validity In logic, specifically in deductive reasoning, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. It is not required for a valid argument to have p ...
—whereas the
contingent In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, langu ...
hinges on the way the particular world is. Concerning
knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is something that is truth, true. The usual test for a statement of fact is verifiability—that is whether it can be demonstrated to correspond to e ...

knowledge
, the ''
a priori ''A priori'' and ''a posteriori'' ('from the earlier' and 'from the later', respectively) are Latin phrases used in philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaph ...
'' is knowable before or without, whereas the ''
a posteriori ''A priori'' and ''a posteriori'' ('from the earlier' and 'from the later', respectively) are Latin phrases used in philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaph ...
'' is knowable only after or through, relevant experience. Concerning
statements Statement or statements may refer to: Common uses *Statement (computer science)In computer programming Computer programming is the process of designing and building an executable computer program to accomplish a specific computing result or to ...
, the '' analytic'' is true via terms'
arrangement In music Music is the of arranging s in time through the of melody, harmony, rhythm, and timbre. It is one of the aspects of all human societies. General include common elements such as (which governs and ), (and its associated c ...

arrangement
and meanings, thus a tautology—true by logical necessity but uninformative about the world—whereas the ''
syntheticA synthetic is an artificial material produced by organic chemistry, organic chemical synthesis. Synthetic may also refer to: In the sense of both "combination" and "artificial" * Synthetic chemical or synthetic compress, produced by the process ...
'' adds reference to a state of facts, a contingency. In 1739,
David Hume David Hume (; born David Home; 7 May 1711 NS (26 April 1711 OS) – 25 August 1776) Cranston, Maurice, and Thomas Edmund Jessop. 2020 999999 or triple nine most often refers to: * 999 (emergency telephone number) 250px, A sign on a beach ...

David Hume
cast a
fork In cutlery or kitchenware, a fork (from la, furca 'pitchfork') is a utensil, now usually made of metal, whose long handle terminates in a head that branches into several narrow and often slightly curved tine (structural), tines with which one ...
aggressively dividing "relations of ideas" from "matters of fact and real existence", such that all truths are of one type or the other. By Hume's fork, truths by relations among ideas (abstract) all align on one side (analytic, necessary, ''a priori''), whereas truths by states of actualities (concrete) always align on the other side (synthetic, contingent, ''a posteriori''). Of any treatises containing neither, Hume orders, "Commit it then to the flames, for it can contain nothing but
sophistry A sophist ( el, σοφιστής, ''sophistes'') was a teacher in ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a civilization belonging to a period of History of Greece, Greek history from the Greek Dark Ages of the 12th–9 ...
and illusion". Thus awakened from "dogmatic slumber",
Immanuel Kant Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about r ...

Immanuel Kant
quested to answer Hume's challenge—but by explaining how
metaphysics Metaphysics is the branch of philosophy that studies the first principles of being, identity and change, space and time, causality, necessity and possibility. It includes questions about the nature of consciousness and the relationship between ...

metaphysics
is possible. Eventually, in his 1781 work, Kant crossed the tines of Hume's fork to identify another range of truths by necessity— synthetic ''a priori'', statements claiming states of facts but known true before experience—by arriving at
transcendental idealism Transcendental idealism is a philosophical system founded by German philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Meta ...
, attributing the mind a constructive role in
phenomena A phenomenon (; plural phenomena) is an observable fact or event. The term came into its modern philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, existence, knowledge ...

phenomena
by arranging
sense data The theory of sense data is a view in the philosophy of perception The philosophy of perception is concerned with the nature of perceptual experience and the status of perceptual data, in particular how they relate to beliefs about, or knowle ...
into the very experience ''space'', ''time'', and ''substance''. Thus, Kant saved
Newton's law of universal gravitation Newton's law of universal gravitation is usually stated as that every particle In the Outline of physical science, physical sciences, a particle (or corpuscule in older texts) is a small wikt:local, localized physical body, object to which can ...
from Hume's
problem of induction The problem of induction is the philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical or mental reality ...
by finding uniformity of nature to be ''a priori'' knowledge. Logical positivists rejected Kant's synthetic ''a priori'', and adopted
Hume's fork Hume's fork, in epistemology Epistemology (; ) is the Outline of philosophy, branch of philosophy concerned with knowledge. Epistemologists study the nature, origin, and scope of knowledge, epistemic Justification (epistemology), justificat ...
, whereby a statement is either analytic and ''a priori'' (thus
necessary Necessary or necessity may refer to: * Need A need is something that is necessary Necessary or necessity may refer to: * Need ** An action somebody may feel they must do ** An important task or essential thing to do at a particular time or by ...
and verifiable logically) or synthetic and ''
a posteriori ''A priori'' and ''a posteriori'' ('from the earlier' and 'from the later', respectively) are Latin phrases used in philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaph ...
'' (thus
contingent In philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, Metaphysics, existence, Epistemology, knowledge, Ethics, values, Philosophy of mind, mind, and Philosophy of language, langu ...
and verifiable empirically).


Observation/theory gap

Early, most logical positivists proposed that all knowledge is based on logical inference from simple "protocol sentences" grounded in observable facts. In the 1936 and 1937 papers "Testability and meaning", individual terms replace sentences as the units of meaning. Further, theoretical terms no longer need to acquire meaning by explicit definition from observational terms: the connection may be indirect, through a system of implicit definitions. Carnap also provided an important, pioneering discussion of disposition predicates.


Cognitive meaningfulness


Verification

The logical positivists' initial stance was that a statement is "cognitively meaningful" in terms of conveying truth value, information or factual content only if some finite procedure conclusively determines its truth. By this verifiability principle, only statements verifiable either by their analyticity or by empiricism were ''cognitively meaningful''.
Metaphysics Metaphysics is the branch of philosophy that studies the first principles of being, identity and change, space and time, causality, necessity and possibility. It includes questions about the nature of consciousness and the relationship between ...

Metaphysics
,
ontology Ontology is the branch of philosophy that studies concepts such as existence, being, Becoming (philosophy), becoming, and reality. It includes the questions of how entities are grouped into Category of being, basic categories and which of these ...

ontology
, as well as much of
ethics Ethics or moral philosophy is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, ...

ethics
failed this criterion, and so were found ''cognitively meaningless''. Moritz Schlick, however, did not view ethical or aesthetic statements as cognitively meaningless. ''Cognitive meaningfulness'' was variously defined: having a
truth value In logic Logic is an interdisciplinary field which studies truth and reasoning Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, Greek: grc, wikt:λογική, λογική, la ...
; corresponding to a possible state of affairs; intelligible or understandable as are scientific statements.
Ethics Ethics or moral philosophy is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, ...

Ethics
and
aesthetics Aesthetics, or esthetics (), is a branch of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of m ...

aesthetics
were subjective preferences, while
theology Theology is the systematic study of the nature of the divine Divinity or the divine are things that are either related to, devoted to, or proceeding from a deity A deity or god is a supernatural The supernatural encompasses supposed ...
and other
metaphysics Metaphysics is the branch of philosophy that studies the first principles of being, identity and change, space and time, causality, necessity and possibility. It includes questions about the nature of consciousness and the relationship between ...

metaphysics
contained "pseudostatements", neither true nor false. This meaningfulness was cognitive, although other types of meaningfulness—for instance, emotive, expressive, or figurative—occurred in metaphysical discourse, dismissed from further review. Thus, logical positivism indirectly asserted Hume's law, the principle that ''is'' statements cannot justify ''ought'' statements, but are separated by an unbridgeable gap.
A. J. Ayer Sir Alfred Jules "Freddie" Ayer (; 29 October 1910 – 27 June 1989), usually cited as A. J. Ayer, was an English philosopher known for his promotion of logical positivism Logical positivism, later called logical empiricism, and both of ...
's 1936 book asserted an extreme variant—the boo/hooray doctrine—whereby all evaluative judgments are but emotional reactions.


Confirmation

In an important pair of papers in 1936 and 1937, "Testability and meaning", Carnap replaced ''verification'' with ''confirmation'', on the view that although universal laws cannot be verified they can be confirmed. Later, Carnap employed abundant logical and mathematical methods in researching inductive logic while seeking to provide an account of probability as "degree of confirmation", but was never able to formulate a model.Mauro Murz
"Rudolf Carnap (1891–1970)"
, ''Internet Encyclopedia of Philosophy'', 12 April 2001.
In Carnap's inductive logic, every universal law's degree of confirmation is always zero. In any event, the precise formulation of what came to be called the "criterion of cognitive significance" took three decades (Hempel 1950, Carnap 1956, Carnap 1961).
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
became a major critic within the logical positivism movement. Hempel criticized the positivist thesis that empirical knowledge is restricted to ''Basissätze''/''Beobachtungssätze''/''Protokollsätze'' (basic statements or observation statements or protocol statements). Hempel elucidated the paradox of confirmation.


Weak verification

The second edition of
A. J. Ayer Sir Alfred Jules "Freddie" Ayer (; 29 October 1910 – 27 June 1989), usually cited as A. J. Ayer, was an English philosopher known for his promotion of logical positivism Logical positivism, later called logical empiricism, and both of ...
's book arrived in 1946, and discerned ''strong'' versus ''weak'' forms of verification. Ayer concluded, "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", but is verifiable in the weak sense "if it is possible for experience to render it probable".Ayer, ''
Language, Truth and Logic ''Language, Truth and Logic'' is a 1936 book about Meaning (philosophy of language), meaning by the philosopher A. J. Ayer, Alfred Jules Ayer, in which the author defines, explains, and argues for the verification principle of logical positivism, s ...
'', 1946, pp. 50–51.
And yet, "no proposition, other than a tautology, can possibly be anything more than a probable
hypothesis A hypothesis (plural hypotheses) is a proposed explanation An explanation is a set of statements usually constructed to describe a set of facts which clarifies the causes, context Context may refer to: * Context (language use), the rel ...
". Thus, all are open to weak verification.


Philosophy of science

Upon the global defeat of
Nazism Nazism ( ), officially National Socialism (german: Nationalsozialismus, ), is the ideology An ideology () is a set of belief A belief is an Attitude (psychology), attitude that something is the case, or that some proposition about th ...

Nazism
, and the removal from philosophy of rivals for radical reform—
Marburg Marburg ( or ) is a college town, university town in the States of Germany, German federal state (''Bundesland'') of Hesse, capital of the Marburg-Biedenkopf Districts of Germany, district (''Landkreis''). The town area spreads along the valley ...
neo-Kantianism, phenomenology,
Heidegger Martin Heidegger (; ; 26 September 188926 May 1976) was a key German philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about reason, ...
's "existential hermeneutics"—and while hosted in the climate of American
pragmatism Pragmatism is a philosophical tradition that considers words and thought as tools and instruments for prediction, problem solving, and action, and rejects the idea that the function of thought is to describe, represent, or mirror reality. Pra ...
and commonsense empiricism, the neopositivists shed much of their earlier, revolutionary zeal. No longer crusading to revise traditional philosophy into a new ''scientific philosophy'', they became respectable members of a new philosophy subdiscipline, ''
philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methodology, methods, and implications of science. The central questions of this study concern Demarcation problem, what qualifies as science, the reliability of s ...
''.Michael Friedman,
Reconsidering Logical Positivism
'' (New York: Cambridge University Press, 1999)
p. xiv
Receiving support from
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 positivism, logical posi ...
, logical empiricists were especially influential in the social sciences.Novick, ''That Noble Dream'' (Cambridge UP, 1988)
p. 546


Explanation

Comtean positivism had viewed science as ''description'', whereas the
logical positivists Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, was a movement in Western philosophy Western philosophy refers to the philosophy, philosophical thought and work of the Western worl ...
posed science as ''explanation'', perhaps to better realize the envisioned
unity of science The unity of science is a thesis in philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methodology, methods, and implications of science. The central questions of this study concern Demarcatio ...
by covering not only
fundamental science Basic research, also called pure research or fundamental research, is a type of scientific research The scientific method is an Empirical evidence, empirical method of acquiring knowledge that has characterized the development of science sinc ...
—that is,
fundamental physics In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic interactions. There are four fundamental interactions known to exist: the gravity, gravitational and ...
—but the
special science {{One source, date=July 2017 Special sciences are those sciences other than fundamental physics In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic intera ...
s, too, for instance
biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanisms, Development ...

biology
,
anthropology Anthropology is the scientific study of human Humans (''Homo sapiens'') are the most abundant and widespread species In biology Biology is the natural science that studies life and living organisms, including their anatomy, ...
,
psychology Psychology is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in the real world. ...

psychology
,
sociology Sociology is a social science Social science is the branch The branches and leaves of a tree. A branch ( or , ) or tree branch (sometimes referred to in botany Botany, also called , plant biology or phytology, is the scie ...
, and
economics Economics () is a social science that studies the Production (economics), production, distribution (economics), distribution, and Consumption (economics), consumption of goods and services. Economics focuses on the behaviour and interact ...

economics
.James Woodward
"Scientific explanation"
– sec 1 "Background and introduction", in Zalta EN, ed,''The Stanford Encyclopedia of Philosophy'', Winter 2011 edn
The most widely accepted concept of scientific explanation, held even by neopositivist critic
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British , and . One of the 20th century's most influential , Popper is known for his rejection of the classical views on the in favour of . According to Popper, a ...

Karl Popper
, was the
deductive-nomological model The deductive inference, deductive-Nomology, nomological model (DN model) of scientific explanation, also known as Carl Gustav Hempel, Hempel's model, the Hempel–Paul Oppenheim, Oppenheim model, the Karl Popper, Popper–Hempel model, or the cove ...
(DN model).James Woodward
"Scientific explanation"
– Article overview, Zalta EN, ed, ''The Stanford Encyclopedia of Philosophy'', Winter 2011 edn
Yet DN model received its greatest explication by
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
, first in his 1942 article "The function of general laws in history", and more explicitly with Paul Oppenheim in their 1948 article "Studies in the logic of explanation". In the DN model, the stated phenomenon to be explained is the ''explanandum''—which can be an event,
law Law is a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its bounda ...
, or
theory A theory is a rational Rationality is the quality or state of being rational – that is, being based on or agreeable to reason Reason is the capacity of consciously making sense of things, applying logic Logic (from Ancient Greek, G ...
—whereas premises stated to explain it are the ''explanans''.Suppe, ''Structure of Scientific Theories'' (U Illinois P, 1977)
pp. 619–21
Explanans must be true or highly confirmed, contain at least one law, and entail the explanandum. Thus, given initial conditions ''C1, C2 . . . Cn'' plus general laws ''L1, L2 . . . Ln'', event ''E'' is a deductive consequence and scientifically explained. In the DN model, a law is an unrestricted generalization by conditional proposition—''If A, then B''—and has empirical content testable. (Differing from a merely true regularity—for instance, ''George always carries only $1 bills in his wallet''—a law suggests what ''must'' be true, and is consequent of a
scientific theory A scientific theory is an explanation of an aspect of the natural science, natural world and universe that has been reproducibility, repeatedly tested and verified in accordance with the scientific method, using accepted protocol (science), protoc ...
's
axiom An axiom, postulate or assumption is a statement that is taken to be truth, true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Greek ''axíōma'' () 'that which is thought worthy or fit' o ...

axiom
atic structure.) By the
Humean Humeanism refers to the philosophy of David Hume David Hume (; born David Home; 7 May 1711 NS (26 April 1711 OS) – 25 August 1776) Cranston, Maurice, and Thomas Edmund Jessop. 2020 999999 or triple nine most often refers to: * 999 (emerg ...
empiricist view that humans observe sequences of events, (not cause and effect, as causality and causal mechanisms are unobservable), the DN model neglects causality beyond mere constant conjunction, first event ''A'' and then always event ''B''. Hempel's explication of the DN model held natural laws—empirically confirmed regularities—as satisfactory and, if formulated realistically, approximating causal explanation. In later articles, Hempel defended the DN model and proposed a probabilistic explanation, inductive-statistical model (IS model). the DN and IS models together form the ''covering law model'', as named by a critic, William Dray. Derivation of statistical laws from other statistical laws goes to deductive-statistical model (DS model).Stuart Glennan
p. 276
in Sarkar S & Pfeifer J, eds, ''The Philosophy of Science: An Encyclopedia'', Volume 1: A–M (New York: Routledge, 2006).
Georg Henrik von Wright, another critic, named it ''subsumption theory'',Manfred Riedel
pp. 3–4
in Manninen J & Tuomela R, eds, ''Essays on Explanation and Understanding: Studies in the Foundation of Humanities and Social Sciences'' (Dordrecht: D Reidel Publishing, 1976).
fitting the ambition of theory reduction.


Unity of science

Logical positivists were generally committed to "Unified Science", and sought a common language or, in Neurath's phrase, a "universal slang" whereby all scientific propositions could be expressed. 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 {{One source, date=July 2017 Special sciences are those sciences other than fundamental physics In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic intera ...
to the terms of another, putatively more fundamental. Sometimes these reductions consisted of set-theoretic manipulations of a few logically primitive concepts (as in Carnap's ''Logical Structure of the World'', 1928). Sometimes, these reductions consisted of allegedly analytic or ''a priori'' deductive relationships (as in Carnap's "Testability and meaning"). A number of publications over a period of thirty years would attempt to elucidate this concept.


Theory reduction

As in Comtean positivism's envisioned
unity of science The unity of science is a thesis in philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methodology, methods, and implications of science. The central questions of this study concern Demarcatio ...
, neopositivists aimed to network all
special science {{One source, date=July 2017 Special sciences are those sciences other than fundamental physics In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic intera ...
s through the covering law model, covering law model of scientific explanation. And ultimately, by supplying boundary conditions and supplying bridge laws within the covering law model, all the special sciences' laws would reduce to
fundamental physics In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic interactions. There are four fundamental interactions known to exist: the gravity, gravitational and ...
, the
fundamental science Basic research, also called pure research or fundamental research, is a type of scientific research The scientific method is an Empirical evidence, empirical method of acquiring knowledge that has characterized the development of science sinc ...
.


Critics

After
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
, key tenets of logical positivism, including its atomistic philosophy of science, the verifiability principle, and the Hume's law, fact/value gap, drew escalated criticism. The verifiability criterion made universal proposition, universal statements 'cognitively' meaningless, and even made statements beyond empiricism for technological but not conceptual reasons meaningless, which was taken to pose significant problems for the philosophy of science. These problems were recognized within the movement, which hosted attempted solutions—Carnap's move to ''confirmation'', Ayer's acceptance of ''weak verification''—but the program drew sustained criticism from a number of directions by the 1950s. Even philosophers disagreeing among themselves on which direction general epistemology ought to take, as well as on
philosophy of science Philosophy of science is a branch of philosophy concerned with the foundations, methodology, methods, and implications of science. The central questions of this study concern Demarcation problem, what qualifies as science, the reliability of s ...
, agreed that the logical empiricist program was untenable, and it became viewed as self-contradictory: the verifiability criterion of meaning was itself unverified. Notable critics included Nelson Goodman,
Willard Van Orman Quine Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic philosophy, analytic tradition, recognized as "one of the most influential philosophers of the ...
, Norwood Hanson,
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as tho ...
,
Thomas Kuhn Thomas Samuel Kuhn (; July 18, 1922 – June 17, 1996) was an American whose 1962 book ' was influential in both academic and popular circles, introducing the term ', which has since become an English-language idiom. Kuhn made several cla ...
, J. L. Austin, Peter Strawson, Hilary Putnam, and Richard Rorty.


Quine

Although an empiricist, American logician
Willard Van Orman Quine Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic philosophy, analytic tradition, recognized as "one of the most influential philosophers of the ...
published the 1951 paper "Two Dogmas of Empiricism", which challenged conventional empiricist presumptions. Quine attacked the analytic-synthetic distinction, analytic/synthetic division, which the verificationist program had been hinged upon in order to entail, by consequence of
Hume's fork Hume's fork, in epistemology Epistemology (; ) is the Outline of philosophy, branch of philosophy concerned with knowledge. Epistemologists study the nature, origin, and scope of knowledge, epistemic Justification (epistemology), justificat ...
, both logical truth, necessity and A priori and a posteriori, aprioricity. Quine's ontological relativity explained that every term in any statement has its meaning contingent on a vast network of knowledge and belief, the speaker's conception of the entire world. Quine later proposed naturalized epistemology.


Hanson

In 1958, Norwood Hanson's ''Patterns of Discovery'' undermined the division of observation versus theory,Novick, ''That Noble Dream'' (Cambridge University Press, 1988)
p. 527
as one can predict, collect, prioritize, and assess data only via some horizon of expectation set by a theory. Thus, any dataset—the direct observations, the scientific facts—is theory-laden, laden with theory.


Popper

An early, tenacious critic was
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British , and . One of the 20th century's most influential , Popper is known for his rejection of the classical views on the in favour of . According to Popper, a ...

Karl Popper
whose 1934 book ''Logik der Forschung'', arriving in English in 1959 as ''The Logic of Scientific Discovery'', directly answered verificationism. Popper considered the
problem of induction The problem of induction is the philosophical Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical or mental reality ...
as rendering empirical verification logically impossible, and the deductive fallacy of affirming the consequent reveals any phenomenon's capacity to host more than one logically possible explanation. Accepting scientific method as hypothetico-deductive model, hypotheticodeduction, whose argument form, inference form is denying the consequent, Popper finds scientific method unable to proceed without falsifiable predictions. Popper thus identifies falsifiability to problem of demarcation, demarcate not ''meaningful'' from ''meaningless'' but simply ''scientific'' from ''unscientific''—a label not in itself unfavorable. Popper finds virtue in
metaphysics Metaphysics is the branch of philosophy that studies the first principles of being, identity and change, space and time, causality, necessity and possibility. It includes questions about the nature of consciousness and the relationship between ...

metaphysics
, required to develop new scientific theories. And an unfalsifiable—thus unscientific, perhaps metaphysical—concept in one era can later, through evolving knowledge or technology, become falsifiable, thus scientific. Popper also found science's quest for truth to rest on values. Popper disparages the ''pseudoscientific'', which occurs when an unscientific theory is proclaimed true and coupled with seemingly scientific method by "testing" the unfalsifiable theory—whose predictions are confirmed by necessity—or when a scientific theory's falsifiable predictions are strongly falsified but the theory is persistently protected by "immunizing stratagems", such as the appendage of ''ad hoc'' clauses saving the theory or the recourse to increasingly speculative hypotheses shielding the theory. Popper's ''scientific'' epistemology is falsificationism, which finds that no number, degree, and variety of empirical successes can either verify or confirm scientific theory. Falsificationism finds science's aim as ''corroboration'' of scientific theory, which strives for scientific realism but accepts the maximal status of strongly corroborated verisimilitude ("truthlikeness"). Explicitly denying the positivist view that all knowledge is scientific, Popper developed the ''general'' epistemology of critical rationalism, which finds human knowledge to evolve by ''conjectures and refutations''. Popper thus acknowledged the value of the positivist movement, driving evolution of human understanding, but claimed that he had "killed positivism".


Kuhn

With his landmark ''
The Structure of Scientific Revolutions ''The Structure of Scientific Revolutions'' (1962; second edition 1970; third edition 1996; fourth edition 2012) is a book about the history of science The history of science covers the development of science Science (from the Latin wo ...
'' (1962),
Thomas Kuhn Thomas Samuel Kuhn (; July 18, 1922 – June 17, 1996) was an American whose 1962 book ' was influential in both academic and popular circles, introducing the term ', which has since become an English-language idiom. Kuhn made several cla ...
critically destabilized the verificationist program, which was presumed to call for foundationalism. (But already in the 1930s,
Otto Neurath Otto Karl Wilhelm Neurath (; 10 December 1882 – 22 December 1945) was an Austria Austria (, ; german: Österreich ), officially the Republic of Austria (german: Republik Österreich, links=no, ), is a landlocked Eastern Alps, East Alp ...

Otto Neurath
had argued for nonfoundationalism via coherentism by likening science to a boat (Neurath's boat) that scientists must rebuild at sea.) Although Kuhn's thesis itself was attacked even by opponents of neopositivism, in the 1970 postscript to ''Structure'', Kuhn asserted, at least, that there was no algorithm to science—and, on that, even most of Kuhn's critics agreed. Powerful and persuasive, Kuhn's book, unlike the vocabulary and symbols of logic's formal language, was written in natural language open to the layperson. Kuhn's book was first published in a volume of ''International Encyclopedia of Unified Science''—a project begun by logical positivists but co-edited by Neurath whose view of science was already nonfoundationalist as mentioned above—and some sense unified science, indeed, but by bringing it into the realm of historical and social assessment, rather than fitting it to the model of physics. Kuhn's ideas were rapidly adopted by scholars in disciplines well outside natural sciences,Novick, ''That Noble Dream'' (Cambridge University Press, 1988)
pp. 526–27
.
and, as logical empiricists were extremely influential in the social sciences, ushered academia into postpositivism or postempiricism.


Putnam

The "Received view of theories, received view" operates on the ''correspondence rule'' that states, "The observational terms are taken as referring to specified phenomena or phenomenal properties, and the only interpretation given to the theoretical terms is their explicit definition provided by the correspondence rules". According to Hilary Putnam, a former student of Hans Reichenbach, Reichenbach and of
Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 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 The Vienna Circle (german: Wiener Kreis) ...
, the dichotomy of observational terms versus theoretical terms introduced a problem within scientific discussion that was nonexistent until this dichotomy was stated by logical positivists. Putnam's four objections: * Something is referred to as "observational" if it is observable directly with our senses. Then an observational term cannot be applied to something unobservable. If this is the case, there are no observational terms. * With Carnap's classification, some unobservable terms are not even theoretical and belong to neither observational terms nor theoretical terms. Some theoretical terms refer primarily to observational terms. * Reports of observational terms frequently contain theoretical terms. * A scientific theory may not contain any theoretical terms (an example of this is Darwin's original theory of evolution). Putnam also alleged that positivism was actually a form of idealism, metaphysical idealism by its rejecting scientific theory's ability to garner knowledge about nature's unobservable aspects. With his "no miracles" argument, posed in 1974, Putnam asserted scientific realism, the stance that science achieves true—or approximately true—knowledge of the world as it exists independently of humans' sensory experience. In this, Putnam opposed not only the positivism but other instrumentalism—whereby scientific theory is but a human tool to predict human observations—filling the void left by positivism's decline.


Fall

By the late 1960s, logical positivism had become exhausted. In 1976,
A. J. Ayer Sir Alfred Jules "Freddie" Ayer (; 29 October 1910 – 27 June 1989), usually cited as A. J. Ayer, was an English philosopher known for his promotion of logical positivism Logical positivism, later called logical empiricism, and both of ...
quipped that "the most important" defect of logical positivism "was that nearly all of it was false", though he maintained "it was true in spirit." Although logical positivism tends to be recalled as a pillar of scientism,
Carl Hempel Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer A writer is a person who uses written words in different styles and techniques to communicate ideas. Writers produce different forms of literary art a ...
was key in establishing the philosophy subdiscipline philosophy of science where
Thomas Kuhn Thomas Samuel Kuhn (; July 18, 1922 – June 17, 1996) was an American whose 1962 book ' was influential in both academic and popular circles, introducing the term ', which has since become an English-language idiom. Kuhn made several cla ...
and
Karl Popper Sir Karl Raimund Popper (28 July 1902 – 17 September 1994) was an Austrian-British , and . One of the 20th century's most influential , Popper is known for his rejection of the classical views on the in favour of . According to Popper, a ...

Karl Popper
brought in the era of postpositivism.
John Passmore John Passmore AC (9 September 1914 – 25 July 2004) was an Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian contin ...
found logical positivism to be "dead, or as dead as a philosophical movement ever becomes". Logical positivism's fall reopened debate over the metaphysical merit of scientific theory, whether it can offer knowledge of the world beyond human experience (scientific realism) versus whether it is but a human tool to predict human experience (instrumentalism).Ruth Lane
"Positivism, scientific realism and political science: Recent developments in the philosophy of science"
''Journal of Theoretical Politics'', 1996 Jul8(3):361–82, abstract.
Meanwhile, it became popular among philosophers to rehash the faults and failures of logical positivism without investigation of them.Friedman, ''Reconsidering Logical Positivism'' (Cambridge, 1999)
p. 1
Thereby, logical positivism has been generally misrepresented, sometimes severely. Arguing for their own views, often framed versus logical positivism, many philosophers have reduced logical positivism to simplisms and stereotypes, especially the notion of logical positivism as a type of foundationalism.Friedman, ''Reconsidering Logical Positivism'' (Cambridge, 1999)
p. 2
In any event, the movement helped anchor
analytic philosophy Analytic philosophy is a branch and tradition of philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about existence Existence is the ability of an entity to interact with physical reality ...
in the English-speaking world, and returned Britain to empiricism. Without the logical positivists, who have been tremendously influential outside philosophy, especially in
psychology Psychology is the scientific Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is an occurrence in the real world. ...

psychology
and other social sciences, intellectual life of the 20th century would be unrecognizable.


See also

*Anti-realism *Empirio-criticism *Moral panic *Raven paradox *Sociological positivism *''The Structure of Science'' *Unobservable


People

*Gustav Bergmann *Herbert Feigl *Kurt Grelling *Friedrich Waismann *R. B. Braithwaite


Notes


References

*Bechtel, William,
Philosophy of Science: An Overview for Cognitive Science
' (Hillsdale NJ: Lawrence Erlbaum Assoc, 1988). *Friedman, Michael,
Reconsidering Logical Positivism
' (New York: Cambridge University Press, 1999). *Novick, Peter,
That Noble Dream: The 'Objectivity Question' and the American Historical Profession
' (Cambridge UK: Cambridge University Press, 1988). *Stahl, William A & Robert A Campbell, Yvonne Petry, Gary Diver,
Webs of Reality: Social Perspectives on Science and Religion
' (Piscataway NJ: Rutgers University Press, 2002). *Suppe, Frederick, ed,
The Structure of Scientific Theories
', 2nd edn (Urbana IL: University of Illinois Press, 1977).


Further reading

*Peter Achinstein, Achinstein, Peter and Stephen Francis Barker, 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'', *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. *Jim Holt (philosopher), 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. *Jangam, R. T. ''Logical Positivism and Politics''. Delhi: Sterling Publishers, 1970. *Janik, Allan and Stephen Toulmin, 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. * Milkov, Nikolay (ed.). ''Die Berliner Gruppe. Texte zum Logischen Empirismus von Walter Dubislav, Kurt Grelling, Carl G. Hempel, Alexander Herzberg, Kurt Lewin, Paul Oppenheim und Hans Reichenbach.'' Hamburg: Meiner 2015. (German) *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. *Richardson, Alan and Thomas Uebel (eds.) ''The Cambridge Companion to Logical Positivism.'' New York: Cambridge University Press, 2007. *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 (ed.)
The Emergence of Logical Empiricism: From 1900 to the Vienna Circle
'. New York: Garland Publishing, 1996. *Sarkar, Sahotra (ed.)
Logical Empiricism at its Peak: Schlick, Carnap, and Neurath
'. New York: Garland Pub., 1996. *Sarkar, Sahotra (ed.)
Logical Empiricism and the Special Sciences
Reichenbach, Feigl, and Nagel''. New York: Garland Pub., 1996. *Sarkar, Sahotra (ed.)
Decline and Obsolescence of Logical Empiricism: Carnap vs. Quine and the Critics
'. New York: Garland Pub., 1996. *Sarkar, Sahotra (ed.)
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. *Stadler, Friedrich.
The Vienna Circle. Studies in the Origins, Development, and Influence of Logical Empiricism
'' New York: Springer, 2001. – 2nd Edition: Dordrecht: Springer, 2015. *Stadler, Friedrich (ed.). ''The Vienna Circle and Logical Empiricism. Re-evaluation and Future Perspectives.'' Dordrecht – Boston – London, Kluwer 2003. *


External links

* Articles by logical positivists
The Scientific Conception of the World: The Vienna Circle

Carnap, Rudolf. 'The Elimination of Metaphysics Through Logical Analysis of Language'




* [https://web.archive.org/web/20110511191629/http://etext.lib.virginia.edu/cgi-local/DHI/dhicontrib2.cgi?id=dv3-69 Feigl, Herbert. 'Positivism in the Twentieth Century (Logical Empiricism)', ''Dictionary of the History of Ideas'', 1974, Gale Group (Electronic Edition)]
Hempel, Carl. 'Problems and Changes in the Empiricist Criterion of Meaning.'
Articles on logical positivism *


Murzi, Mauro. 'Logical Positivism', ''The New Encyclopedia of Unbelief'', Tom Flynn (ed.). Prometheus Books, 2007 (PDF version)



Passmore, John. 'Logical Positivism', ''The Encyclopedia of Philosophy'', Paul Edwards (ed.). New York: Macmillan, 1967, first edition
Articles on related philosophical topics
Hájek, Alan. 'Interpretations of Probability', ''The Stanford Encyclopedia of Philosophy (Summer 2003 Edition), Edward N. Zalta (ed.)''

Rey, Georges. 'The Analytic/Synthetic Distinction', ''The Stanford Encyclopedia of Philosophy (Fall 2003 Edition)'', Edward N. Zalta (ed.)

Ryckman, Thomas A., 'Early Philosophical Interpretations of General Relativity', ''The Stanford Encyclopedia of Philosophy (Winter 2001 Edition), Edward N. Zalta (ed.)''

Woleński, Jan. 'Lvov-Warsaw School', ''The Stanford Encyclopedia of Philosophy (Summer 2003 Edition), Edward N. Zalta (ed.)''

Woodward, James. 'Scientific Explanation', ''The Stanford Encyclopedia of Philosophy (Summer 2003 Edition), Edward N. Zalta (ed.)''
{{Authority control Logical positivism, Analytic philosophy Empiricism Epistemological theories Epistemology of science History of science Linguistic turn Meaning in religious language Philosophical movements Philosophical schools and traditions Philosophy of science Positivism Theories of language Western philosophy