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عدد الرسائل : 1500
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تاريخ التسجيل : 26/10/2009
وســــــــــام النشــــــــــــــاط : 6
 | |  Whether the verificationist agenda was pursued in a formalist or pragmatic vein, however, all members shared the belief that meaningful statements divided exclusively into analytic and synthetic statements which, when asserted, were strictly matched with | |
Yet even if it be conceded that the members of the Vienna Circle did not harbour undue reductionist-foundationalist ambitions, the question remains open whether they were able to deal with the complexities of scientific theory building.Here the prominent role of Schlick must be mentioned, whose General Theory of Knowledge(1918, second edition 1925) was one of the first publications by (future) members of the Vienna Circle to introduce the so-called two-languages model of scientific theories. According to this model, scientific theories comprised an observational part formulated with observational predicates as customarily interpreted, in which observations and experiential laws were stated, and a theoretical part which consisted of theoretical laws the terms of which were merely implicitly defined, namely, in terms of the roles they played in the laws in which they figured. Both parts were connected in virtue of a correlation that could be established between selected terms of the theoretical part and observational terms. In the second half of the 1920s, however, Schlick’s model, involving separate conceptual systems, was put aside in favor of a more streamlined conception of scientific theories along lines as suggested by the Aufbau. Clearly, however, Schlick’s model represents an early form of the conception of scientific theories as uninterpreted calculi connected to observation by potentially complicated correspondence rules that Carnap reintroduced in (1939) and that became standard in the “received view”. (Another, albeit faint precursor was the idea contained in a 1910 remark of Frank’s pointing out the applicability of Hilbert’s method of implicit definition to the reconstruction empirical scientific theories as conceived, also along the lines of two distinct languages, by the French conventionalists Rey and Duhem; see Uebel 2003.)Even granted the model in outline, questions arise both concerning its observational base as well as its theoretical superstructure. We already discussed one aspect of the former topic, the issue of protocols, in the previous section; let’s here turn to the latter topic. Talk of correspondence rules only masks the problem that is raised by theoretical terms. One of the pressing issues concerns their so-called surplus meaning over and above their observational consequences. This issue is closely related to the problem of scientific realism: are there truth-evaluatable matters of fact for scientific theories beyond their empirical, observational adequacy? Even though the moniker “neo-positivism” would seem to prescribe an easy answer as to what the Vienna Circle’s position was, it must be noted that just as there is no consensus discernible today there was none in the Circle beyond certain basics that left the matter undecided.All in the Vienna Circle followed Carnap’s judgement in Pseudoproblems of Philosophy(1928b) and Schlick’s contention in his response to Planck’s renewal of anti-Machian polemics (1932) that questions like that of the reality of the external world were not well-formed ones but only constituted pseudo-questions. While this left the observables of empirical reality clearly in place, theoretical entities remained problematical: were they really only computational fictions introduced for the ease with which they they allowed complex predictive reasoning, as Frank (1932) held? This hardly seems to do justice to the surplus meaning of theoretical terms over and above their computational utility: theories employing them seem to tell us about non-observable features of the world. This indeed was Feigl’s complaint (1950) in what must count as the first of very few forays into “semantical realism” (scientific realism by another word) by a former member of the Vienna Circle—and one that was quickly opposed by Frank’s instrumentalist rejoinder (1950). Carnap sought remain aloof on this as on other ontological questions. So while in the heyday of the Vienna Circle itself the issue had not yet come into clear focus, by mid-century one could distinguish amongst its surviving members both realists (Feigl) and anti-realists (Frank) as well as ontological deflationists (Carnap).Carnap’s general recipe for avoiding undue commitments (while pursuing his investigations of various language forms, including the intensional ones Quine frowned upon) was given in terms of the distinction between so-called internal and external questions (1950a). Given the adoption of a logico-linguistic framework, we can state the facts in accordance with what that framework allows us to say. Given any of the languages of arithmetic, say, we can state as arithmetical fact whatever we can prove in them; to say that accordingly there are numbers, however, is at best to express the fact that numbers are a basic category of that framework (irrespective of whether they are logically derived from a still more basic category). As to whether certain special types of numbers exist (in the deflated sense), that depends on the expressive power of the framework at hand and on whether the relevant facts can be proven. Analogous considerations apply to the existence of physical things (the external world) given the logico-linguistic frameworks of everyday discourse and empirical science. (The near-tautologous nature of these categorical claims in Carnap’s hands echoes his earlier diagnosis of metaphysical claims as pseudo-statements; see also 1934/37, Part V.A.) Unlike such internal questions, however, external questions, questions whether numbers or electrons “really exist” irrespective of any framework, are ruled out as illegitimate and meaningless. The only way in which sense could be given to them was to read them as pragmatic questions concerned with the utility of talk about numbers or electrons, of adopting certain frameworks. Carnap clearly retained his allegiance to the linguistic turn: existence claims remain the province of science and there must be seen as mediated by the available conceptual tools of inquiry. Logicians of science are in no position to double-guess the scientists in their own proper domain.Matters came to a head with the discovery of a proof (see Craig 1956) that the theoretical terms of a scientific theory are dispensable in the sense of it being possible to devise a functionally equivalent theory that does not make use of them. Did this not rob theoretical terms of their distinctive role and so support instrumentalism? The negative answer was twofold. As regards defending their utility, Carnap (1963b, §24) agreed with Hempel (1958) that in practice theoretical terms were indispensible in facilitating inductive relations between observational data. As regards the defense of their cognitive legitimacy, Carnap held that this demanded determining what he called their “experiential import”, namely, determining what specifically their empirical significance consisted in. It was for this purpose that Carnap came to employ Ramsey’s method of regimenting theoretical terms. Nowadays this so-called ramseyfication is often discussed as a means for expressing a position of “structural realism”, a position midway between fully-blown scientific realism and anti-realism and so sometimes thought to be of interest to Carnap. Carnap’s own concern with ramseyfication throws into relief not only the question of the viability of one of the Vienna Circle’s most forward-looking stances in the debate about theoretical terms—intending to avoid both realism and anti-realism—but also several other issues that bear on the question of which, if any, forms of Vienna Circle philosophy remain viable. 3.5 Carnap’s Later Meaning Criterion and the Problem of RamseyficationNote that the issue of realism vis-à-vis theoretical terms is closely related to two other issues central to the development of Vienna Circle philosophy: Carnap’s further attempts to develop a criterion of empiricist significance for the terms of the theoretical languages of science and his attempts to defend the distinction between synthetic and analytic statements with regard to such theoretical languages.In 1956 Carnap introduced a new criterion of significance specifically for theoretical terms (1956b). This criterion was explicitly theory-relative. Roughly, Carnap first defined the concept of the “relative significance” of a theoretical term. A term is relatively significant if and only if there exists a statement in the theoretical language that contains it as the only non-logical term and from which, in conjunction with another theoretical statement and the sets of theoretical postulates and correspondence rules, an observational statement is derivable that is not derivable from that other theoretical statement and the sets of theoretical postulates and correspondence rules alone. Then Carnap defined the “significance” of a theoretical term in terms of it belonging to a sequence of such terms such that each is relatively significant to the class of those terms that precede it in the sequence. Now those theoretical statements were legitimate and cognitively significant that were well-formed and whose descriptive constants were significant the sense just specified. It is clear that by the stepwise introduction of theoretical terms as specified, Carnap sought to avoid the deleterious situations that rendered Ayer’s criterion false (and his own of 1928). Nevertheless, this proposal too was subjected to criticism (e.g., Rozeboom 1960, Kaplan 1975a). A common impression amongst philosophers appears to be that this criterion failed as well, but this judgement is by no means universally shared (for the majority view see Glymour 1980, for a contrary assessment see Sarkar 2001). Thus it has been argued that subject to some further refinements, Carnap’s proposal can be made to work (Creath 1976, Justus 2014)—as long as the sharp distinction between observational and theoretical terms can be sustained. (In light of the objections to the latter distinction one wants to add: or by a dichotomy of terms functionally equivalent to it.)Carnap’s own position on his 1956 criterion appears somewhat ambiguous. While he is reported to have accepted one set of criticisms (Kaplan 1975b), he also asserted still after they had been put to him that he thought his 1956 criterion remained adequate (1963b, §24b). Even so, Carnap there also advised investigation of whether yet another, then entirely new approach to theoretical terms that he was developing would allow for an improved meaning criterion for them. Yet when Carnap offered “the Ramsey method” as a method of characterizing the “empirical meaning of theoretical terms” it was not their empirical significance as such but the specific empirical import of theoretical terms that he considered (1966, Ch. 26). What prompted him to undertake his investigations of ramseyfications was not dissatisfaction with his 1956 proposal as a criterion of significance for theoretical terms, but it was the consequence that with its model of the theoretical language it proved impossible to draw the distinction between synthetic and analytic statements in the theoretical language. The reason for this was that the postulates for the theoretical language also specify factual relations between phenomena that fall under the concepts that are implicitly defined by them. (As noted, a similar problem already had plagued Carnap’s analyses of disposition terms ever since he allowed for non-eliminative reduction chains.)Carnap’s attempt to address this problem by ramseyfication was published in several places from 1958 onwards. (See Carnap 1958, 1963, §24C-D and the popular exposition 1966, Chs. 26 and 28; compare Ramsey 1929 and see Psillos 1999, Ch.3. This proposal and a variant of it (1961b) were both presented in his 1959 Santa Barbara lecture (published in Psillos 2000a); as it happened, Kaplan presented his criticism (1975a) of Carnap’s 1956 criterion at the same conference.) With ramseyfication Carnap adverted again to entire theories as the unit of assessment. Ramseyfication consists in the replacement of the theoretical terms of a finitely axiomatized theory by bound higher-order variables. This involves combining all the theoretical postulates which define theoretical terms (call this conjunction T) and correspondence rules of a theory which link some of these theoretical terms with observational ones (call this C) in one long sentence (call this TC) and then replacing all the theoretical predicates that occur in it by bound higher-order variables (call this RTC). This is the so-called Ramsey-sentence of the entire theory; in it no theoretical terms appear, but it possesses the same explanatory and predictive power as the original theory: it has the same observational consequences. However, Carnap stressed that the Ramsey sentence cannot be said to be expressed in a “simple” but only an “extended” observational language, for due to its higher-order quantificational apparatus it includes “an advanced complicated logic embracing virtually the whole of mathematics” (1966, [1996, 253]).To distinguish between analytic and synthetic statements in the theoretical language Carnap made the following proposal. Let the Ramsey sentence of the conjunction of all theoretical postulates and the conjunction of all correspondence rules of that theory be considered as expressing the entire factual, synthetic content of the scientific theory and its terms in their entirety. By contrast, the statement “RTC → TC” expressed the purely analytic component of the theory, its “A-postulate” (or so-called Carnap sentence). This “A-postulate states that if entities exist (referred to by the existential quantifiers of the Ramsey sentence) that are of a kind bound together by all the relations expressed in the theoretical postulates of the theory and that are related to observational entities by all the relations specified by the correspondence postulates of the theory, then the theory itself is true.” Or differently put, the A-postulate “says only that if the world is this way, then the theoretical terms must be understood as satisfying the theory” (1966 [1996, 271]). With RTC → TC expressing a meaning postulate of sorts Carnap claimed to have separated the analytic and synthetic components of a scientific theory.Carnap’s adoption of the Ramsey method met mainly with criticism (Psillos 1999, ch.3, 2000b, Demopoulos 2003), even though ramseyfications continue to be discussed as a method of characterizing theoretical terms in a realist vein (albeit with conditions not yet introduced by Carnap, as in Lewis 1970, Papineau 1996). With Carnap’s ramseyfications we do not even get the answer that what really exists is the structure that the ramseyfication at hand identifies. Given the absence of a clause requiring unique realizability, ramseyfications counseled modesty: the structure that is identified remains indeterminate to just that degree to which theoretical terms remain incompletely interpreted (Carnap 1961b). To this we must add that for Carnap ramseyfications of theoretical terms can support only internal existence claims: he explicitly reaffirmed his confidence in the distinction between internal and external question to defuse the realism/anti-realism issue (1966 [1996, 256]). This strongly suggests that with these proposals Carnap did not intend to deviate from his deflationist approach to ontology.What must be considered, however, is that Carnap’s proposal to reconstruct the contribution of theoretical terms by ramseyfication falls foul of arguments deriving from M.H.A. Newman’s objection to Russell’s structuralism in Analysis of Matter (see Demopoulos and Friedman 1985). This objection says that once they are empirically adequate, ramseyfied theories are trivially true, given the nature of their reconstruction of original theories. Russell held that “nothing but the structure of the external world is known”. But if nothing is known about the generating relation that produces the structure, then the claim that there exists such a structure is vacuous, Newman claimed. “Any collection of things can be organised so as to have the structureW, provided there are the right number of them.” (Newman 1928, 144) To see how this so-called cardinality constraint applies to ramseyfications of theories, note that in Carnap’s hands, the non-observational part of reconstructed theories, their theoretical entities, were represented by “purely logico-mathematical entities, e.g. natural numbers, classes of such, classes of classes, etc.” For him the Ramsey sentence asserted that “observable events in the world are such that there are numbers, classes of such, etc., which are correlated with events in a prescribed way and which have among themselves certain relations”, this being “clearly a factual statement about the world” (Carnap 1963b, 963). Carnap here had mathematical physics in mind where space-time points are represented by quadruples of real numbers and physical properties like electrical charge-density or mass-density are represented as functions of such quadruples of real numbers.The problem that arises from this for Carnap is not so much the failure to single out the intended interpretation of the theory: as noted, Carnap clearly thought it an advantage of the method that it remained suitably indeterminate. The problem for Carnap is rather that, subject to its empirical adequacy, the truth conditions of the Ramsey-sentences are fulfilled trivially on logico-mathematical grounds alone. As he stated, Ramsey-sentences demand that there be a structure of entities that is correlated with observable events in the way described. Yet given the amount of mathematics that went into the ramseyfied theory—“virtually the whole of mathematics”—some such structure as demanded by the Ramsey-sentence is bound to be found among those entities presupposed by its representational apparatus. (The cardinality constraint is no constraint at all.) That any theory is trivially true for purely formal reasons (as long as it is empirically adequate) counts against Carnap’s proposal to use Ramsey sentences as reconstructions of the synthetic content of the theoretical part of empirical scientific theories. Given that with ramseyfications “the truth of physical theory reduces to the truth of its observational consequences” (Demopoulos and Friedman 1985, 635), this is a problem for Carnap’s project on its own terms: any surplus empirical meaning of theoretical terms that Carnap sought to capture simply evaporates (Demopoulos 2003).This result casts its shadow over Carnap’s last treatment of theoretical terms in its entirety and threatens further consequences. If the reconstruction of empirical theories by ramseyfication in Carnap’s fashion is unacceptable, then all explications that build on this are called into question: explications of theoretical analyticity as much as explications of the experiential import of theories. Given that no justice has been done to the experiential import of theoretical terms, it seems clear that one must ask whether the analytic components of a theoretical language have been correctly identified. If they have not, then the meta-theoretical utility of the synthetic/analytic distinction is once again be called into question.One is lead to wonder whether Carnap would not be well advised to return to his 1956 position. This allowed for a criterion of empirical significance for theoretical terms but not for the analytic/synthetic distinction to be sustained with regard to the theoretical language. According to Carnap’s fall-back position before he hit upon ramseyfication, it was thought possible to distinguish narrow logical truth from factual truth in the theoretical language (1966, Ch. 28). Yet it is difficult to silence the suspicion that an analytic/synthetic distinction that applies only to observational languages—and admits inescapable semantical holism for theoretical languages—is not what the debate between Carnap and Quine was meant to be all about. Attempts have thus been undertaken recently to provide an interpretation of Carnap’s ramseyfications that contains or mitigates the effects of the Newman objection (Friedman 2008, 2011, and Uebel 2011). What has become clear is that much is at stake for Carnap’s formal explicationism, indeed for the standard logical empiricist model of scientific theories (see below). | |
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