NEOPOSITIVISM. - Neopositivism, also called logical positivism, recognizes its formal beginning in the founding of the Wienerkreis (Vienna Circle), which took place in 1928 within the E. Mach Society, already existing in that city. The principal aim of neopositivism is the one common to every form of positivism (v.), namely to provide a secure foundation for the sciences and to demonstrate the meaninglessness of all metaphysics (v.); and this community of intent may be said to be almost the only link between neopositivism and the classical positivism of Comte and his 19th-century successors. Its essential characteristic, on the other hand, lies in the exclusive use of logical analysis to demonstrate positivist theses.
Neopositivism is therefore a synthesis of empiricism, derived especially from Hume and from Mach, and of that current of formal logic or logistic which, starting from Leibniz, through Boole and De Morgan, was constituted especially through the work of Peirce, Frege, Peano, Russell and the Polish school. Nevertheless, the title of father of neopositivism belongs to Ludwig Wittgenstein, whose Tractatus logico-philosophicus (London 1922) remains to this day the fundamental work, by means of which it is possible to explain the various themes of the school and also its various conflicting positions. Neopositivism spread rapidly from Austria to Germany, the United States and, to a different degree, also to France, England and Italy; and the principal reason for its success lies in the fact that neopositivism presents itself as the official philosophy of the new physics and as the philosophical interpretation of the thought of Einstein and of Heisenberg. The principal founders of the Vienna Circle were Moritz Schlick, Rudolf Carnap, Hans Reichenbach, Otto Neurath. Following the anti-Jewish persecutions in Germany and the annexation of Austria, many of these philosophers moved to America, gathering in the Chicago school, together with local elements, among them John Dewey, Charles W. Morris, Julius R. Weinberg, etc. In Italy, Peano, Pieri and Vailati are considered precursors of neopositivism; Federigo Enriques as having kindred tendencies; and as followers or admirers, Ludovico Geymonat, the Centro di studi metodologici of Turin (N. Abbagnano, P. Buzzano, E. Frola), and the Centro di metodologia e analisi del linguaggio of Milan (S. Ceccato, V. Somenzi, G. Vaccarino).
The fundamental principle of neopositivism consists in adopting as a universal categorical principle what is a methodological principle of modern physics: the meaning of every proposition is the method of its verification, that is, the only questions that have a sense are those in which one seeks the result of one or more experiences that, at least conceptually, can be carried out. In other words, the only propositions that have a meaning are those entirely translatable into the language of physics; and this led Neurath to designate the neopositivist theory by the term Physicalism (Physikalismus, in Scientia, 50 [1931], pp. 297-303). With this empiricist principle there must be joined, for neopositivism, the possibility of logic, which is taken in a purely nominalistic sense, as a set of propositions concerning the form of discourse and the rules of transformation of one proposition into another of identical meaning. All logical propositions are therefore tautological, and from this derives their necessity and universality; and their sole task is to facilitate the recognition of tautologies when reasoning is complicated. For Wittgenstein, indeed, in accordance with the fundamental empiricist principle, the propositions of logic express no meaning, they are an important non-sense (Weinberg). This constitutes a grave difficulty for neopositivism, since a logic that cannot be expressed is a contradiction in terms; Carnap overcame this difficulty by distinguishing a double language: the syntactical language and the object language. To Carnap's logical syntax is due the impulse toward the purest linguistic formalism of logic and of science itself.
On these bases, neopositivism claims the elimination of metaphysics by means of the logical analysis of meaningful discourse. If in fact meaningful assertions are limited to what is empirically verifiable, and if all demonstrations and logical operations are reduced to tautological transformations, it follows that every metaphysical statement, which by definition is a non-empirical proposition, is a pseudo-proposition, devoid of meaning. Metaphysics is not an error, nor an illusion, but simply a non-sense. And on the same basis is founded the theory of scientific method, in which particular attention is devoted to natural laws, which by their universality do not have a direct empirical sense. For Wittgenstein they are incomplete propositions, devoid of meaning, and must be taken solely as prescriptive rules for the formation of singular empirical propositions concerning the future; for Carnap, on the other hand, they are universal propositions endowed with sense, insofar as they express the class of all particular propositions that are consequences of them; for both, however, they can never have an absolute value, but only a probabilistic and provisional one.
Against all these theories there stands an objection, which has not escaped their own authors; namely the difficulty, or even the impossibility, of constructing in terms of possible experience alone an intersubjective and objective world, such as is the world that is the object of physical science: within my personal experience, which is the only experience possible for me, it makes no sense to speak of the experiences of others, of other subjects, of communication between individuals. One thus falls into linguistic solipsism, from which it is impossible to escape either with the empiricist principle alone or with the pure logical syntax of language. The effort of neopositivism is to overcome the difficulty by exasperating still further the formalism of language, to the point of excluding from it every mention not only of facts and data, but also of experience; even the protocol language (expressing the direct report of an individual's personal experience), according to Neurath, must have from the outset an impersonal and formal character without extralinguistic reference. The problem of solipsism is thus radically eliminated, it is true; not, however, in the sense of intersubjectivity and objectivity, but in that of a pure impersonalism and nominalism and at the same time of an absolute conventionalism; in fact, even for protocol propositions the criterion of truth, fundamental to all positivism, is abandoned, that is, the positive fact, independent of the researcher; and all propositions are no longer judged except on the internal coherence of language. Thus logical positivism or neopositivism proves self-contradictory; for either it accepts the purely empirical meaning of propositions, and then it empties logic of all meaning; or it shuts itself up in the formalism of pure logic, and then it loses all contact with the absolute reality of the objective datum (v. METODOLOGIA).