Editing Logical positivism (section)

===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>