DOI: 10.4324/0123456789-DD3600-1
Version: v1,  Published online: 2018
Retrieved May 18, 2022, from

3. The logical positivists and ideal language philosophy

Wittgenstein’s Tractatus soon came to the attention of the logical positivists of the Vienna Circle, a group of scientifically minded philosophers and philosophically minded scientists who aimed to put philosophy on a scientific footing by combining a thoroughgoing empiricism with the new logic of Frege and Russell (Carnap et al. 1929; see also Logical positivism).

David Hume had divided all ‘objects of human reason or inquiry’ into ‘Relations of Ideas’ and ‘Matters of Fact’, condemning all propositions belonging to neither category – including the propositions of metaphysics – as ‘sophistry and illusion’ (Hume 1777: 165). In a similar vein, Kant had distinguished ‘analytic’ from ‘synthetic’ judgements, depending on whether or not the predicate is (implicitly) contained in the concept of the subject. He had also separated a posteriori knowledge, which is based on experience, from a priori knowledge, which is independent of experience not as regards its origin, but as regards its validity (Kant 1787: B1–18). By contrast to Hume, Kant recognized the possibility of judgements that are both synthetic and a priori, namely those of mathematics and metaphysics.

The logical positivists updated both Kant’s dichotomies and Hume’s ‘fork’ in a thoroughly linguistic register. Logic and mathematics, they conceded, are necessary and a priori; yet they do not amount to knowledge about the world. For all a priori truths are analytic, that is, true solely in virtue of the meanings of their constituent words (for alternative conceptions of analyticity, see Analyticity ). Logical truths are tautologies in the sense of Wittgenstein’s Tractatus, i.e. true in virtue of the meaning of the logical constants alone, and analytical truths can be reduced to tautologies by substituting synonyms for synonyms (Ayer 1946: ch. 4). Hume’s fork turned into the ‘principle of verification’: a proposition ‘is literally meaningful if and only if it is either analytic or empirically verifiable’ (Ayer 1946: 12). Unlike the propositions of mathematics and logic, metaphysical propositions are not analytic, for they purport to be about the world, and hence their truth or falsity must be determined by whether or not they describe the world correctly. Yet unlike the propositions of empirical science, metaphysical propositions are not empirically verifiable. What empirical observation could possibly verify (e.g.) F.H. Bradley’s idealist claim that ‘the Absolute enters into, but is itself incapable of, evolution and progress’ (Ayer 1946: 49)? Being neither analytic nor empirically verifiable, the positivists concluded that metaphysical propositions are cognitively meaningless pseudo-propositions (Carnap 1932). Legitimate philosophy boils down to what Rudolf Carnap called ‘the logic of science’ (1937: 279). Its task is the logico-linguistic explication of those propositions which alone are strictly speaking meaningful, namely those of science. Rounding off this linguistic turn, Carnap reformulated philosophical problems and propositions from the traditional ‘material mode’ – concerning the nature or essence of objects – into the formal mode – concerning linguistic expressions, their syntax and semantics.

In line with their scientific outlook, the positivists’ merged the linguistic turn with ideal language philosophy. According to Carnap, the attempt to reveal the underlying logical form of sentences in the vernacular is futile; analysis should instead take the form of logical construction. His method of ‘logical explication’ does not aspire to provide a synonym of the analysandum but rather to replace it with an alternative expression or construction, one which serves the cognitive purposes of the original equally well while avoiding drawbacks such as obscurity and undesirable ontological commitments. For instance, talk about numbers can be replaced by talk about sets of sets (see Carnap, R.).

Citing this article:
Glock, Hans-Johann and Javier Kalhat. 3. The logical positivists and ideal language philosophy. Linguistic turn, 2018, doi:10.4324/0123456789-DD3600-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
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