Editing Logical positivism (section)

==History==

===Vienna and Berlin Circles===

{{Main|Vienna Circle}}

The [[Vienna Circle]] was led principally by [[Moritz Schlick]], congregating around the [[University of Vienna]] and at the [[Café Central]]. A manifesto written by [[Otto Neurath]], [[Hans Hahn (mathematician)|Hans Hahn]] and [[Rudolf Carnap]] in 1929 summarised the Vienna Circle's positions. Schlick had originally held a [[neo-Kantianism|neo-Kantian]] position, but later converted, via Carnap's 1928 book ''Der logische Aufbau der Welt'' (''The Logical Structure of the World''). The Viennese maintained closely cooperative ties with the [[Berlin Circle]], among whom [[Hans Reichenbach]] was pre-eminent. [[Carl Hempel]], who studied under Reichenbach in Germany, was also to prove influential in the movement's later history.<ref name="sep-hempel"/> A friendly but tenacious critic of the movement was [[Karl Popper]], whom Neurath nicknamed the "Official Opposition".<ref>{{cite journal |last=Bartley |first=W. W. |year=1982 |title=The Philosophy of Karl Popper Part III. Rationality, Criticism, and Logic |journal=Philosophia |volume=11 |issue=1-2 |pages=121–221 |doi=10.1007/bf02378809 |issn=0048-3893}}</ref>

Early in the movement, Carnap, Hahn, Neurath and others recognised that the [[logical positivist#Verifiability Criterion of Meaning|verifiability criterion]] was too stringent in that it rejected [[universal generalization|universal statements]], which are vital to [[hypothesis|scientific hypothesis]].<ref name=Sarkar2005/> A radical ''left wing'' emerged from the Vienna Circle, led by Neurath and Carnap, who proposed revisions to weaken the criterion, a program they referred to as the "liberalisation of empiricism". A conservative ''right wing'', led by Schlick and [[Friedrich Waismann|Waismann]], instead sought to classify universal statements as analytic truths, thereby to reconcile them with the existing criterion.<ref>{{harvnb|Uebel|2008}} 3.1</ref> Within the liberal wing Carnap emphasised [[fallibilism]], as well as [[pragmatics]], which he considered integral to [[empiricism]]. Neurath prescribed a move from [[Ernst Mach|Mach]]'s [[phenomenalism]] to [[physicalism]], though this would be opposed by Schlick. As Neurath and Carnap sought to pose science toward social reform, the split in the Vienna Circle also reflected political differences.<ref name=Sarkar2005/>

Both Schlick and Carnap had been influenced by and sought to define logical positivism versus the neo-Kantianism of [[Ernst Cassirer]], the contemporary leading figure of the [[Marburg school]], and against [[Edmund Husserl]]'s [[phenomenology (philosophy)|phenomenology]]. Logical positivists especially opposed [[Martin Heidegger]]'s obscure metaphysics, the epitome of what they had rejected through their epistemological doctrines. In the early 1930s, Carnap debated Heidegger over "metaphysical pseudosentences".<ref name=Friedman-pxii>{{harvnb|Friedman|1999}} p. xii</ref>

===Anglosphere===

As the movement's first emissary to the [[New World]], Moritz Schlick visited [[Stanford University]] in 1929, yet otherwise remained in Vienna and was murdered in 1936 at [[University of Vienna|the University]] by a former student, [[Johann Nelböck]], who was reportedly deranged.<ref name=Friedman-pxii/> That year, [[A. J. Ayer]], a British attendee at various Vienna Circle meetings since 1933, published ''[[Language, Truth and Logic]]'', which imported logical positivism to the [[English-speaking world]]. In 1933, the [[Nazi Party]]'s rise to power in Germany had triggered flight of intellectuals, which accelerated upon Germany's [[annexation of Austria]] in 1938.<ref name=Friedman-pxii/> The logical positivists, many of whom were [[Jewish]], were targeted and continued flight throughout the pre-war period. Their philosophy thus became dominant in the [[English-speaking world]].<ref>{{cite book |chapter=Logical Positivism The Vienna Circle |first=Bruce |last=Caldwell |year=1984 |title=Beyond Positivism |pages=29–36 |doi=10.4324/9780203565520-7 |publisher=Routledge |isbn=978-0-429-23433-0}}</ref>

By the late 1930s, many in the movement had replaced [[phenomenalism]] with Neurath's [[physicalism]], whereby [[material object]]s are not reducible to [[Stimulus (physiology)|sensory stimuli]] but exist as publicly observable entities in the [[reality|real world]]. Neurath settled in England, where he died in 1945. Carnap, Reichenbach and Hempel settled permanently in America.<ref name=Friedman-pxii/>

===Post-war period===

Following the [[World War 2|Second World War]], logical positivism—now referred to by some as ''logical empiricism''—turned to less radical objectives in the [[philosophy of science]]. Led by [[Carl Gustav Hempel|Carl Hempel]], who expounded the [[covering law model]] of [[scientific explanation]], the movement became a major underpinning of [[analytic philosophy]] in the English-speaking world<ref>{{harvnb|Uebel|2008}} 2.1</ref> and its influence extended beyond philosophy into the [[social science]]s. At the same time, the movement drew intensifying scrutiny over its central problems<ref name="Smith1986">{{cite book |first=L.D. |last=Smith |year=1986 |title=Behaviorism and Logical Positivism: A Reassessment of the Alliance |publisher=Stanford University Press |isbn=978-0804713016 |lccn=85030366 |page=314}}</ref><ref name="Bunge1996">{{cite book |first=M.A. |last=Bunge |year=1996 |title=Finding Philosophy in Social Science |publisher=Yale University Press |isbn=978-0300066067 |lccn=lc96004399 |page=317 |quote=However, neo-positivism failed dismally to give a faithful account of science, whether natural or social. It failed because it remained anchored to [[sense data|sense-data]] and to a [[phenomenalism|phenomenalist]] metaphysics, overrated the power of [[inductive reasoning|induction]] and underrated that of [[hypothesis]], and denounced [[philosophical realism|realism]] and [[materialism]] as metaphysical nonsense. Although it has never been practiced consistently in the advanced natural sciences and has been criticized by many philosophers, notably Popper (1959, 1963), logical positivism remains the tacit philosophy of many scientists.}}</ref> and its doctrines were increasingly criticised, most trenchantly by [[Willard Van Orman Quine]], [[Norwood Russell Hanson|Norwood Hanson]], [[Karl Raimund Popper|Karl Popper]], [[Thomas Samuel Kuhn|Thomas Kuhn]] and [[Carl Gustav Hempel|Carl Hempel]].<ref name=sep-vienna-circle/>