Vindicating the verifiability criterion

Philosophical Studies https://doi.org/10.1007/s11098-023-02071-w Vindicating the verifiability criterion Hannes Leitgeb1 Accepted: 27 October 2023 © The Author(s) 2023 Abstract The aim of this paper is to argue for a revised and precisified version of the infamous Verifiability Criterion for the meaningfulness of declarative sentences. The argument is based on independently plausible premises concerning probabilistic confirmation and meaning as context-change potential, it is shown to be logically valid, and its ramifications for potential applications of the criterion are being discussed. Although the paper is not historical but systematic, the criterion thus vindicated will resemble the original one(s) in some important ways. At the same time, it will also be more modest insofar as meaningfulness will turn out to be relativized linguistically and probabilistically, and different choices of the linguistic and probabilistic parameters may lead to different verdicts on meaningfulness. Keywords Verifiability · Confirmation · Meaning · Context-change potential · Pragmatism · Probability It is hard to think of any other philosophical statement that has received so much criticism over the years as the logical empiricists’ infamous Verifiability Criterion of meaning(fulness) for declarative sentences.1 The formulations of the Criterion changed over the years, but one variant of its original formulation may be summarized as: The connection between meaning and confirmation has sometimes been formulated by the thesis that a sentence is meaningful if and only if it is verifi- 1 Here are some of the most relevant references: Hempel (1950, 1951), Passmore (1967), Soames (2003), and Lycan (2019) are highly critical of the Verifiability Criterion, while Uebel (2019) and Creath (2021) hint at its partial salvageability, and Lutz (2012, 2017), Justus (2014), and Glock (2021) seek to effect partial salvage, though not in the way the present paper will do. * Hannes Leitgeb 1 Faculty of Philosophy, Philosophy of Science and Religious Studies, Ludwig-MaximiliansUniversity, Geschwister‑Scholl‑Platz 1, D‑80539 Munich, Germany 13 Vol.:(0123456789) H. Leitgeb able, and that its meaning is the method of its verification (Carnap, 1936a, p. 421).2 And yet, in what follows, I will show that there is a strong argument for a reasonably revised and precisified version of the Verifiability Criterion. The underlying aims will not be exegetical but systematic: far from being just a flawed proposal by philosophers of the past, there is a version of the Verifiability Criterion that follows from plausible up-to-date assumptions about confirmation and meaning and which deserves a place in contemporary semantics, pragmatics, epistemology, and philosophy of science. Reasoning towards that conclusion will proceed in four stages corresponding to Sects. 1–4. Section 1 will take the familiar step of improving the original formulation of the Verifiability Criterion by replacing verifiability by (dis-)confirmability, Sect. 2 will be devoted to the explication of (dis-)confirmability, and Sects. 3 and 4 to that of meaning and meaningfulness. By then, I will have all premises available for stating the argument in Sect. 5, discussing its ramifications in Sect. 6, and summarizing what was achieved and where one might go from there in Sect. 7. Along the way, I will build upon existing work on probabilistic confirmation, meaning as context-change potential, and related probabilistic variants of the Criterion (Skyrms, 1984, 1985; Sober, 1990, 2008). Although the whole enterprise is only inspired by classical sources on the Verifiability Criterion without being committed to them, the criterion thus vindicated will end up resembling the original one(s) in important ways; at the same time, it will be more modest and more likely to be applied for other purposes than originally expected. 1 From verification to (dis‑)confirmation The first step towards a defense of the Verifiability Criterion we do not actually need to take ourselves, as (some of) the logical empiricists already took it early on: to replace verifiability by confirmability. Indeed, 2 Carnap (1936a) continues by dismissing this “Older Requirement of Verifiability” in favor of a substantial modification. I will mostly rely on Carnap references in this paper. This said, the Verifiability Criterion did not actually play a major role in Carnap’s work in semantics, in which he reconstructed meaning in terms of truth conditions, or in his work on probability, in which he gave probabilistic explications of confirmation but not of meaningfulness; see Supplement E, Section 1, of Leitgeb and Carus (2021) for further discussion. However, Carnap’s work in philosophy of science—such as, in his most mature formulation, Carnap (1956)—did offer important deductive criteria for the empirical significance of theoretical terms and sentences (see Creath, 1976 for a defense of Carnap, 1956 against potential counterexamples, and see Lutz, 2012; Justus, 2014, and Lutz 2017 for further critical assessments and developments). The basic idea of Carnap (1956) was to determine the empirical significance of sentences from that of terms, and to determine the empirical significance of a term by the existence of a sentence including that term as its only descriptive term, such that the sentence makes a difference for the prediction of an observable state of affairs. The present paper will deal solely with a probabilistic explication of meaningfulness of sentences, where meaningfulness will consist in making communicative difference that shows up probabilistically. 13 Vindicating the verifiability criterion no complete verification is possible but only a process of gradually increasing confirmation (Carnap, 1936a, 1936b, p. 425, his emphases). E.g., it would be practically, nomically, and logically impossible to use a finite conjunction of observation sentences to strictly verify a universal law hypothesis that quantifies over all physical bodies at all places and times (unless one does not regard laws as sentences but as rules of inference, in which case reasoning with negations or disjunctions of laws would become problematic). Hence, strict verifiability seems to be too restrictive as a meaningfulness criterion. In contrast, a gradually increasing confirmation of universal sentences is feasible (see also Carnap, 1963 and Passmore, 1967 on this point). While Carnap (1936a, 1937) still aimed to explicate confirmation deductively, Carnap (1945) already turned to probabilistic explications in which increasing absolute confirmation would ultimately be reconstructed as resulting from iterated incremental confirmation (which will the topic of next section). Furthermore, mere confirmability should really be extended to the disjunctive confirmability or disconfirmability, as a declarative sentence is meaningful just in case its negation is (see e.g. Hempel, 1950, pp. 52–53) and th (...truncated)