Positivism - Logical Positivism

Logical Positivism

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

Logical positivism grew from the discussions of a group called the "First Vienna Circle" which gathered at the Café Central before World War I. After the war Hans Hahn, a member of that early group, helped bring Moritz Schlick to Vienna. Schlick's Vienna Circle, along with Hans Reichenbach's Berlin Circle, propagated the new doctrines more widely in the 1920s and early 1930s. It was Otto Neurath's advocacy that made the movement self-conscious and more widely known. A 1929 pamphlet written by Neurath, Hahn, and Rudolf Carnap summarized the doctrines of the Vienna Circle at that time. These included: the opposition to all metaphysics, especially ontology and synthetic a priori propositions; the rejection of metaphysics not as wrong but as having no meaning (by meaning positivists meant not empirically verifiable); a criterion of meaning based on Ludwig Wittgenstein's early work (which he later refuted); the idea that all knowledge should be codifiable in a single standard language of science; and above all the project of "rational reconstruction," in which ordinary-language concepts were gradually to be replaced by more precise equivalents in that standard language. However, the project is widely considered to have failed:

The secondary and historical literature on logical positivism affords substantial grounds for concluding that logical positivism failed to solve many of the central problems it generated for itself. Prominent among the unsolved problems was the failure to find an acceptable statement of the verifiability (later confirmability) criterion of meaningfulness. Until a competing tradition emerged (about the late 1950's), the problems of logical positivism continued to be attacked from within that tradition. But as the new tradition in the philosophy of science began to demonstrate its effectiveness — by dissolving and rephrasing old problems as well as by generating new ones — philosophers began to shift allegiances to the new tradition, even though that tradition has yet to receive a canonical formulation. —L.D. Smith, Behaviorism and Logical Positivism: A Reassessment of the Alliance

In the early 1930s, the Vienna Circle dispersed, mainly because of fascist persecution and the untimely deaths of Hans Hahn and Schlick. The most prominent proponents of logical positivism emigrated to the United Kingdom and to the United States, where they considerably influenced American philosophy. Until the 1950s, logical positivism was the leading school in the philosophy of science. After moving to the United States, Carnap proposed a replacement for the earlier doctrines in his Logical Syntax of Language. This change of direction and the somewhat differing views of Reichenbach and others led to a consensus that the English name for the shared doctrinal platform, in its American exile from the late 1930s, should be "logical empiricism."

Most philosophers consider logical positivism to be, as John Passmore expressed it, "dead, or as dead as a philosophical movement ever becomes". By the late 1970s, its ideas were so generally recognized to be seriously defective that one of its own main proponents, A. J. Ayer, could say in an interview: "I suppose the most important ...was that nearly all of it was false."