Carnap’s Transformation of Epistemology and the Development of His Metaphilosophy

thomas.uebel@manchester.ac.uk

Abstract: Carnap’s lectures at the 1935 Paris Congress for the Unity of Science marked the beginning of his mature metaphilosophy. This paper considers what role remained for epistemology once it was “purified” of all psychological elements as Carnap demanded. It is argued that while this did mean the end of traditional epistemology room was found for non-traditional versions in the course of the further development of Carnap’s logic of science.

Famous for his deflationary approach to philosophy, Burton Dreben appears to have acknowledged an exemplary predecessor in Rudolf Carnap, for he is reported by Richard Creath to have held that Carnap’s philosophical project no longer had anything to do with epistemology (1992, Fn. 3). Why should anyone think that an empiricist—even a logical empiricist like Carnap—took such an attitude? One can begin to see why when studying the 1935 lecture “Von der Erkenntnistheorie zur Wissenschaftslogik” (“From the Theory of Knowledge to the Logic of Science”). There Carnap described the three “main phases” of the “development of scientific philosophy” as follows:

The first concerns the overcoming of metaphysics, the transition from speculative philosophy to the theory of knowledge. The second step consisted in the overcoming of the synthetic a priori; it led to an empiricist epistemology. … The task of our present work appears to me to consist in the transition from epistemology to the logic of science. (1936a, 36)1

Carnap here announced to a wider audience the new metaphilosophical position he had first articulated the previous year in his forbidding Logical Syntax (1934a/1937, §§ 72-73): philosophy becomes the logic of science. To be sure, Carnap added:

In this process epistemology is not abandoned in its entirety, as metaphysics and apriorism were previously, but it is purified and dissolved [aufgelöst] into its constituents. (1936a, 36)

But what did the “purification” or “dissolution” consist in, what kind of inquiries does the logic of science allow? Does it make sense to call what remained “epistemology”? My concern in this paper is to address precisely this, the nature of epistemology and its place in Carnap’s mature metaphilosophy.2 I shall argue

1 Translations of texts where none are listed in the bibliography are but by the present author. Translations of passages from Carnap (1936a) that were integrated into Carnap (1949) follow the latter with occasional amendments.2 Alan Richardson (1996, 1997, Chs. 8-9) insightfully investigated the role of Carnap (1936a) in resolving tensions in his philosophy as they emerge from a partly Neokantian reading of his

that there is considerable force to Dreben’s suspicion and that although Creath’s countersuggestion that Carnap’s very logic is epistemological in spirit is very much to the point, it needs still further supplementation. Only then can it be seen clearly not only what kind of epistemology Carnap rejected, but also what kind of epistemology he himself pursued and what still other kind he abstained from but which his overall conception allowed colleagues to pursue.3

1.. Carnap’s New Program. The paper under consideration belongs with “Wahrheit und Bewährung” (the original of “Truth and Confirmation”) and “Über die Einheitssprache der Wissenschaft. Logische Bemerkungen zum Project einer Enzyklopädie” (“On the Unified Language of Science. Logical Remarks on the Project of an Encyclopedia”) to the trio of lectures that Carnap wrote for the 1935 Paris Congress on the Unity of Science (1936a, 1936b, 1936c). Their place in Carnap’s oeuvre marks the end of the syntactic and the start of his semantic period of theorizing about the language of science. They sum up certain results of his work so far and open it towards broader perspectives on what he then called “the logic of science”. All three papers announce that Carnap had broken free of previous limitations—with each focusing on a different liberation: from overly restrictive “psychologism”, overly restrictivesyntacticism, and overly restrictive empiricist reductionism, respectively.4 In doing so they spelt out central ingredients of Carnap’s now classic and highly orginal metaphilosophy. Long past the speculative stage, philosophy was no longer to reconstruct the way in which a given contested concepts had to be understood. Philosophy became conceptual engineering, the construction of ways in which contested concepts could be understood. Such reconstructions no longer had to answer to an underlying essence but only faced pragmatic constraints of the theorist’s own choosing. Carnap’s new metaphilosophy—with the “principle of tolerance” at its center5—was the long-term result of significant discoveries reached by

Aufbau (1928a). My concern is a different one and focuses on the development of his views on epistemology from the 1930s onward.3 Terminological note: Given my primary focus on the mid-1930s when Carnap’s philosophy of tolerance was introduced, I will use, to start with, the term “logic of science” which Carnap employed through the period up to (1938, §1) but abandoned from (1939) onwards. I will return to these terminological matters in §4 below. 4 The applicability of “psychologism” and “reductionsm” needs comment. (i) Carnap took to heart Popper’s criticism that the epistemology pursued by him until late 1932 and Neurath throughout was “psychologistic”. Popper distinguished between “objective science” and “our knowledge” and considered concern with the latter “psychologistic” (1934/1958, 98). Popper’s highly idiosyncratic use of the term was defended by Carnap against Neurath as criticism of the idea that “the testing of a hypothesis has to go back to experience- or perception statements” (February 13, 1935, RC 029-09-84 ASP). We’ll see examples of Carnap’s anti-psychologism in §2 below. The difference of reactions to Popper between Carnap and Neurath corresponds to the difference in the tasks addressed by Carnap’s logic of science and Neurath’s “behavioristics” or pragmatics of science and is reflected in their different preferences for the form and content of protocol sentences; see Uebel (2007, 287-292) and (2015). We’ll see examples in §§3-4 below. (ii) The reductionism abandoned in (1936c) was a meaning-theoretical, not an ontological one, of demanding dispositional concepts to be explicitly definable in terms of concepts of observable properties, relations, or processes (as in, e.g., 1932b and 1932c).5 “The Principle of Tolerance: It is not our business to set up prohibitions, but to arrive at conventions. . . . In logic, there are no morals. Everyone is at liberty to build up his own logic, i.e., his own form of language, as he wishes. All that is required of him is that, if he wishes to discuss it, he must state his methods clearly, and give syntactical rules instead of philo sophical

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attempting to synthesize Hilbert’s metamathematics and Wittgenstein’s Tractatus claim that one could not use language to speak about language (Awodey and Carus 2007), discoveries that led Carnap first to his logical syntax project and then to his long-term effort to transcend its limitations.

At first glance Carnap’s new steps in these three papers may not appear so remarkable. The points made might seem to be only of a technical nature. Consider the opening towards semantics in “Truth and Confirmation”, made possible by Alfred Tarski’s truth definition as a complement to the impossibility results about logical syntax he had learned from Kurt Gödel. Or consider the gradual (re-)separation of the theoretical language and its concepts from the observational language, starting in “On the Unified Language of Science” with the correction of his Vienna-period reductionist ambitions towards disposition terms. One may think: fair enough, Carnap conceded to semantics its own domain and realized that some concepts cannot be explicitly defined, or fully defined, in extensional terms. These might appear unspectacular, even rather banal, developments, but that would be to misunderstand their importance.

To begin with, nothing was ever “only technical” for Carnap. But especially here we must remember that it was Carnap’s struggles for the correct analysis of dispositional predicates that entered the history of the philosophy of science as the utterly basic and fundamental lesson in logical analysis as which we teach it nowadays. More generally, it was Carnap who at the time pioneered formal theories of language, even formal epistemology as such. What we nowadays presuppose as matters-of-course was created in part by Carnap. To be sure, the glory of discovery belonged to Gödel and Tarski, but Carnap was a logician of first rank operating right along them: it fell to him to work through their innovations and to apply them to general philosophy of science and language. But even this characterization still deceives, for it only points to the fact that what is well-known now once was new. What is most interesting about Carnap’s mature philosophy is that following attentively his movements of thought offers insights and results that lead elsewhere than to what is known already—or at least leads to looking at what is already known with a critical eye.

Consider Carnap’s formal semantics in this light. As a theorist who regarded languages as calculi (1934a/1937, §2), he witnessed the development of model theory and employed some of its concepts but always warned against the misunderstanding them as psychologically descriptive. As he understood it, a theory of language understanding involved far more than semantics and the latter was ill served by the demands of the former. So the concepts of model and relation of reference as well as the concept of intension, all of which abstract from the complex phenomena of human language use, were not to be regarded as fully representative of language-in-use. For Carnap, formal semantics was an autonomous domain of inquiry the results of which could not be read into psychology or, for that matter, epistemology or ontology. Neurath’s repeated criticism in their correspondence that his semantics contained a hidden

arguments. ” (1934a/1937, §17). The first use of this principle dates to (1932d) when Carnap affirmed the conventionality of the choice of reconstructive language forms with regard to the evidential basis of empirial science; see below §2.

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correspondentist metaphysics must have struck Carnap as bizarre—as bizarre as Gilbert Ryle’s related accusation that Carnap had revived the “Fido”-Fido theory of meaning (1949): that was precisely the opposite of his intention. But we may regard both criticisms as symptomatic of the difficulty of getting the right measure of Carnap’s approach to philosophy. It is easy to mistrust its austerity and read back into it precisely what he wanted excised. With all this in mind, let’s turn to Carnap’s “purification” of epistemology and his “dissolution” of it into its “parts”. In his new conception of the logic of science, Carnap focused exclusively on logical and structural considerations, while psychological ones were eliminated entirely. These two aspects of Carnap’s new conception are not easy to understand correctly either.

There are two types of facts which the investigations of modern scientific philosophy are thought to—but do not really—make reference to: the phenomenal and the physical facts. Epistemology in the narrower sense appeared to concern itself with the ‘phenomena’, the ‘immediate given’, with ‘experiences’, the ‘mere contents of consciousness’, that is, with facts like, e.g., ‘Here is pain now’ or ‘I see a red spot’. But actually the investigation of such facts would be a matter for psychology and the employment of its empirical method: the dependence of the processes on different factors must be determined, the results must be analyzed statistically, and formulated in the form of general laws. The physical facts constitute the subject matter of so-called ‘philosophy of nature’. Here it was thought that we are dealing with the analysis of space and time, of causality and determinism, etc. But if it really were a matter of analysis of natural processes, then the questions would have been those of natural science and not of philosophy. (1936a, 38)

Carnap distinguished sharply between philosophy and empirical investigations. By excluding reference to “phenomenal facts” he contradicted the traditional conception of epistemology. But, strikingly, his strictures went still further to exclude psychological facts generally and so would seem to have excluded the investigation not just of “the given” and “mere contents of consciousness”, etc., but of any properties of a person’s beliefs or judgments, of what she holds true.6 What then, we must ask, remains of epistemology in the new logic of science?

For Carnap, it is the sciences that deal with questions of fact, while philosophy deals with how the sciences speak about whatever they presume to be facts. Philosophy is is not an alternative to science but its metatheory. To dispell the puzzlement his pronouncement was likely to arouse, he explained how the logic of science proceeds:

We do well therefore to reformulate questions and sentences so that the appearance is avoided that they refer to facts and that it becomes clear instead that they refer to language. We call this reformulation a translation of the contentful (or material—we really should say: pseudo-

6 This is of course the peculiar Popperian sense of “anti-psychologism” that Carnap defended against Neurath; see Fn. 3 above.

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material) mode of speech into the formal mode of speech. We will no longer ask: “Are phenomena to count as the most basic facts to which all other facts are reducible?” Here it is utterly incomprehensible what it would mean to reduce one fact to another. Rather we shall formulate the question as follows: “Are there ultimate sentences to which all synthetic sentences are reducible?” What reducibility is can be defined precisely within the framework of logical syntax. And, further, we replace the question ‘Of what form are the most basic phenomena?’ with the question ‘Of what (logico-syntactic) form are the ultimate sentences?’ (1936a, 38-39)

In order to engage in a type of philosophy that is truly purified of psychology and natural science we can only speak of sentences and their logical properties. What Carnap called the “material” and “formal” modes designate ways of metalinguistic speech, ways of talking about ways of talking about facts. Carnap rejected the material mode as misleadingly speaking of reference as if it denoted physical or psychological relations and he insisted on using the formal mode for discussing formal-logical features of the linguistic objects. (At first Carnap allowed only what he considered to be syntactic characterizations into formal talk, but from 1935 onwards he also allowed semantic characterizations into formal speech and then gradually phased out the material/formal distinction.)

Epistemology in the framework of philosophy as metatheory can therefore only mean investigating logical relations between sentences. But which logical relations are epistemologically significant? As already in Pseudoproblems in Philosophy, we are to take the logical relation of implication to provide us with a concept relevant to justification that is suitably cleansed of psychology and empirical concerns (1928b, §1). The network of sentences derivable from others represents what matters philosophically about the concept of justification—and it is all that matters.

The change of perspective that Carnap urges here is quite stunning. Little if anything seems to remain of epistemology as commonly understood. For instance, what place remains for reasoning about the justification of beliefs? Now we may admit that it’s not beliefs that stand in relations of derivability but the sentences expressing them, but can’t we speak about beliefs at one remove, at it were? Yet beliefs are psychological entities and so cannot form the subject matter of a de-psychologized epistemology like the logic of science. The purification appears to amount to eliminative cleansing.

Similarly stunned we can ask whether the concern with “ultimate sentences” was not logic-of-science shorthand for talk of the phenomenal given and so allowed the question of foundations to retain significance, but Carnap responded negatively. To the objection that “in the end it does not matter whether we ask for the structure of phenomena or the structure of sentences, for if the sentences do describe the phenomena, then they have the same structure as these,” he replied:

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But actually it does matter how we formulate the question. For the formulation in the formal mode of speech speaks of sentences and thereby draws our attention to the circumstance that our formulation is still incomplete, for in addition a specification of what language the question is articulated in is needed. This will make it clear to us that in the end it is a question of convention which structure we give to the basic sentences of our language. (This is not to say, however, that it does not matter what structure we choose.) (1936a, 39)

Carnap here invoked the doctrine of logico-linguistic tolerance according to which we must choose between different possible forms of discourse none of which are privileged by the way things are but are answerable to different interests. Note how Carnap conceived of the putatively “ultimate sentences,” that replaced reference to the “most basic facts”. These sentences were highly de-personalized—like the atomic or elementary sentences in Wittgenstein’s Tractatus (1922)—but at the same time (and in this respect very different from the Tractatus) they were relieved of their transcendental correspondence-theoretical tie to reality, to what is “really” given. Unlike the picture theory of meaning, which demanded an isomorphism of structure between representation and the represented, Carnap’s logic of science contemplates a kind of “ultimate sentences” that seem to be free-floating. What makes these sentences “ultimate” is simply that with them testing stops—at least provisionally.7

So Carnap’s logic of science appears to lead into an epistemological no-man’s land, with ersatz-justification cut loose from epistemic subjects and no fixed evidence base. Clearly Carnap did not feel constrained by traditional expectations. As in the case of semantics, we must be prepared to think in new ways when it comes to the logic of science.8 The logic of science offers no mere redescription of traditional epistemology but something entirely new, namely the purely logical analysis and construction of linguistic frameworks, networks of concepts and totalities of sentences in terms relations of derivability.9 But to what purpose? Carnap meant to offer us logical frameworks and conceptual networks for possible use. (If the frameworks at issue are of an elementary scientific nature—as they were in Physikalische Begriffsbildung (1926)—one can count his investigations into metrology.)10 The logic of science as the tool of philosophical, i.e., conceptual engineering offers proposals for new ways of

7 Here it must also be remembered that despite the slightly misleading terminology used here, Carnap had decisively abandoned appeal to basic or elementary sentence as epistemologically binding in (1932d).8 Maybe once and when the new subdiscipline is up and properly running we can relate its deliverances to more or less traditional concerns—but not before. The blueprint for such a linkage could be Carnap’s incipient theory of interpretation that was built holistically on pragmatic complements to semantic concepts but was not reducible to them; see Carnap (1955b), his response to Chisholm’s criticism (1955) that the simple pairing of pragmatic correlates of intensions with types of stimulations in Carnap (1955a) overlooks how a subject takes the stimulation, given her prior history. 9 The term “framework” itself is not yet used in quite just this sense but it is clear that logico-linguistic frameworks are at issue in (1934a/1937, §17).10 For this interpretation, see Richardson (2012).

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talking and thinking without insisting that they are the right ones for all purposes.

In what sense then could this logic of science serve as an epistemology? If the epistemological concept of justification is replaced by the logical concept of derivability, it follows that the logic of science can only deal with one sort of justification at all—and that in only a highly attenuated fashion. To employ terms of contemporary epistemology, it can only investigate questions of propositional justification, not doxastic justification. It can only investigate whether there is justification for the proposition at issue in a knowledge claim, namely whether it stands in the appropriate logical relations to other propositions that could be regarded as antecedently established, but it could not investigate whether a particular knower is justified in making this claim. Moreover, the logic of science can only investigate under what conditions there would be justification for the proposition at issue in a knowledge claim: after all, qua logic it can make no assumptions about what synthetic sentences are true. And all along, of course, the logic of science must abstract entirely—unlike contemporary theories of propositional justification—from whether the propositions in question are actually entertained by anybody or not. Carnap really does seem to have been proposing an “epistemology without a knowing subject”.11 So one may well ask, with Dreben, whether all this should still count as epistemology.

2.. The Path to the New Program. To fully understand what Carnap’s “purification” of epistemology amounts to, we must first ask what prompted Carnap to reject traditional epistemological concerns so radically. One obvious reason lies buried in a many-layered debate that itself is responsible for a number of different developments in the philosophy of the Vienna Circle. One central issue in this so-called protocol-sentence debate was the issue of whether the epistemological perspective of methodological solipsism, which Carnap had employed in the Aufbau (1928a) at a high level of abstraction, continued to be useful when applied to concrete scientific knowledge claims. Carnap’s alternative answer, following Neurath’s lead, was negative. Since methodological solipsism embodies the traditional conception of the epistemic priority of phenomenalistic over physicalistic statements, Carnap’s abandonment of methodological solipsism represents a rejection of traditional epistemology.

It will be objected quite correctly that there are epistemologies that do not build upon the assumption of epistemic priority of phenomenalist statements over physicalist ones. While this is true it must be asked whether such non-methodologically solipsist epistemologies were common currency at the time. And to this the answer is negative. To be sure, beginnings of antifoundationalist epistemology can be discerned in Deweyan pragmatism—and strangely antifoundationalist noises were even made on the far right of German phenomenology—but Neurath’s forceful rejection of the idea that the phenomenal given commanded epistemic authority that remained unchecked by any criteria whose satisfaction was intersubjectively observable was highly

11 To be sure, Carnap’s version came without the metaphysics attached to Popper’s later and not wholly dissimilar construction (1968).

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unusual. So the force of this objection to Carnap’s abandonment of methodological solipsism is diminished, once the historical context is taken into account. When Carnap joined Neurath’s declaration “that within a consistent physicalism there can be no ‘theory of knowledge’, at least not in the traditional form” (1932a/1983, 67), they were in the very vanguard of a post-foundationalist epistemology whose entire field had yet to be defined.12

That said, the suspicion lingers that a bit more is involved than overcoming the dastardly methodological solipsism, when the extremely austere nature of Carnap’s replacement is questioned. In particular, it may be asked quite reasonably not only why it should be considered a psychologistic sin to call upon an individual epistemic subject’s history, her current circumstances and concurrent beliefs, in order to justify her knowledge claims, but to investigate the justification of beliefs at all. (Surely this is a Popperian step too far, as Neurath had already objected.)13 One candidate answer to this question readily comes to mind: behaviorism or eliminative materialism. Showing that this answer will not do requires a brief review of Carnap’s involvement in the aforementioned debate with Neurath.

To begin with, it must be stressed, lest one be distracted by the later attitude of logico-linguistic tolerance, that the protocol-sentence debate started over the issue of how a philosopher’s rational reconstruction had to conceive of the most basic evidence statements of empirical science (“protocol sentences”). And in contrast to his own later position of tolerance, Carnap, too, started with no qualms about determining the content of protocol sentences in terms of the phenomenal contents of an individual consciousness (“auto-psychological sentences”). But things changed, and the debate went as follows. To accord with the intersubjective character of science it became necessary for autopsychological sentences to be fully translatable into a physical language: only once they were “physicalized,” in this sense, did they become intersubjectively testable. The consequence was drastic. Originally, the autopsychological sentences were supposed to formulate what was immediately given and so provide epistemological foundations. But if they are regarded as physicalistic sentences, they fall under the purview of an epistemology that offers the justification only by reference to intersubjective protocol sentences. Accepting the primacy of the intersubjective physicalist language withdrew the unconditional epistemological privilege of first-person reports.14 It meant the abandonment of methodological solipsism.

Now by the time Carnap conceded this, he had embraced the principle of logico-linguistic tolerance in all but name (1932d). This meant, of course, that he

12 It may be wondered whether a subtle thinker enlivened by the principle of tolerance like Carnap could possibly agree with a philosophical ruffian like Neurath issuing categorical denials like “There can be no…”. But just as Neurath from the mid-30s onward was happy to follow Carnap and translate his metatheoretical assertions into proposals, so Carnap agreed with his opposition to reconstructions of the language of science on a methodologically solipsist basis on pragmatic grounds—and therefore abandoned its employment.13 See Fn. 3 above.14 Under certain circumstances even a physicalist can grant first-person psychological reports a relative privilege.

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abandoned methodological solipsism neither as impossible on some grounds or other nor as untrue to “real” cognition. (The pre-tolerance program of rational reconstruction had already rejected the latter aim.) Yet Carnap’s abandonment of methodological solipsism—and his acceptance of the primacy of the intersubjective physicalist language—was no less forceful for being pragmatically grounded. It meant that methodological solipsism represented a pointless pandering to traditional epistemology and metaphysics that lacked any utility for the explication of science as practiced. What shows that skepticism of the mental was not an issue is that a settled position was reached only when the bona fide legitimacy of introspective verifications of auto-psychological sentences was established within the framework of physicalism.15

First, by 1930, in “The Old and the New Logic”, Carnap conceded that the physicalist language had to be considered an equally original or basic language alongside the phenomenal language (which it was not in the Aufbau) so as to be able to account for the intersubjectivity of scientific discourse. (If everyone had to translate every sentence of the public language into their own phenomenal protocol language language, then it became highly questionable—it certainly remained beyond intersubjective confirmability—whether everybody shared a common language.)16 Here the exclusive use of the autopsychological languages for reconstructive purposes of all discourse was abandoned, but as yet no full intertranslatability between the two languages obtained, for autopsychological sentences were still said to resist translation into physicalist ones.17

Second, by the end of 1931 when he completed the published version of “Unity of Science” (1932b/1934), Carnap had also broken the language-theoretical or translational primacy of the methodologically solipsist language. The previous asymmetry in its favor was ended insofar as now autopsychological sentences too were held to be translatable into the physical language. This allowed for intersubjective discourse about other’s and one’s own mental states. However, all physicalistic sentences still had to be translated into autopsychological

15 For the details of the first three steps in this development, see Uebel (2007, Chs. 6-8). The full details of the last step—just how first-person psychological reports were integrated into the physicalist language by allowing both direct first-person and indirect third-person verification—were set out by Carnap only in “Les concepts psychologiques et les concepts physiques sont-ils foncièrement different?” (1935); see Uebel (in preparation).16 This is the argument undermining the Aufbau’s attempt to reconstruct intersubjectivity reportedly put to Carnap by Hans Neider, probably in late 1929; for discussion of this argument in context see Uebel (2007, 131-137). Note that the starting point for this argument is the methodologically solipsist constructional system actually developed in the Aufbau, not what he there says could be but is not actually developed (like a system with a physicalistic base). It may perhaps be held that reconstructing reflexive intersubjectivity not only lies outside of the capability of methodological solipsism but is not the task of rational reconstructions as defined in the Aufbau. Against this it can be pointed out that failure to reconstruct reflexive intersubjectivity shows up a radical shortcoming of this philosophical methodology: the transparency of scientific discourse itself is treated as a rationally inessential, negligible extra. In any case, Carnap did take the bait this challenge represents (as is shown by his engagements in the protocol-sentence debate).17 Proof can be found in manuscripts of 1930 where Carnap spoke of two “universal” languages, a physicalistic and a phenomenalistic one where, however, the first, unlike the second, only translated all intersubjective languages; see Uebel (2007, Ch. 6) for details from the archives.

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sentences for epistemological purposes, i.e. to allow their justification to be established by epistemic subjects.18

Third, by the end of 1932, in “On Protocol Sentences” (1932d), his final answer to Neurath, Carnap had also abandoned this epistemological primacy of the autopsychological sentences. Now physicalistic sentences no longer needed to be translated into autopsychological ones for purposes of epistemological analysis. The methodologically solipsist language lost the last of the privileges it had possessed until then. The form, content and status of protocol sentences were up for conventional determination: this marked the emergence of logical tolerance. But there remained another step to be taken.

Fourth, by early 1935, Carnap made it clear that auto-psychological sentences were verifiable directly via introspection as well as indirectly via behavioral indicators thereby granting them a legitimate sense. From step two until then, due to his reliance on the distinction of the material and formal modes of speech, it had been necessary to discard the intuitive introspective understanding of auto-psychological sentences as reliant on illusory “object representations.” (To be properly understood, they required translation into the physicalist language.) Now this intuitive understanding became amenable to articulation in the formal mode by allowing that autopsychological sentences could serve in their own right as control- or protocol sentences. Doing so required that the thesis of physicalism was reformulated so that it demanded not the translatability of psychological terms into physical terms but only their equipollence, their mutual derivability, and reformulating the criterion of cognitive significance so that it allowed for different ways of verification or confirmation (1935). In the case at hand, the equipollence in question was “P-equipollence”: according to this, the “logical content” of a non-analytic sentence was determined by its derivability relations to protocol sentences, relations which could make use not only of logical “L-rules” but also of synthetic “P-rules”, i.e. empirical laws (1934a/1937, §52). And the P-rules at issue concerned correlations between introspectively accessible psychological states and intersubjectively observable behavior, the former accounting for direct, the latter for indirect verifiability (1935).19

What step four corrected was an unwarranted consequence that step two seems to threaten: that first-person psychological sentences gained all their cognitive content from their physicalistic translation. With step four methodological solipsism was overcome without doing violence to standard intuitions about the importance of first-person access to certain psychological reports. Introspection understood correctly was perfectly compatible with physicalism. It follows that

18 Carnap still wrote in the summer of 1932: “In the case of a sentence about the present state of one’s own mind, e.g., P1 ‘I am now excited’ one must clearly distinguish between the system sentence P1 and the protocol sentence p2, which, likewise, ‘I am now excited’. The difference rests in the fact that the system sentence P1 may, under certain circumstances, be disavowed, whereas a protocol sentence, being an epistemological point of departure, cannot be rejected.” (1932c/1959, 191)19 That statements “can be transformed in more than one way with equal content” was stated already in (1934b, 16) the composition of which seem to date to 1933, yet the explicit pluralization of methods of verification was not stated until (1935) which Carnap wrote in January 1935.

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dropping methodological solipsism need not mean dropping introspective psychological reports but only false conceptions of their nature and status.20 It also follows that it was not positivist mistrust of the mental that prompted Carnap’s anti-psychologistic austerity.

What then prompted Carnap’s “anti-psychologism”? The very talk of replacing epistemology by the logic of science suggests the answer. As noted above, logic cannot adjudicate empirical matters. It’s not that non-linguistic entities could have been included but are excluded from its domain, rather the logic of science is only equipped to investigate logical relations. Being an a priori inquiry it is incapable of engaging with anything but (possible) sentences of the language of science, their logical syntax and (later) their semantics. Limited by constraint of scope, the logic of science had to bracket the investigation of all empirical matters, especially the network of causal relations between information-carrying states underlying knowledge as commonly understood.

We are thrown back to the question “Why turn to the logic of science?” and the answer we get is simply that that is what philosophy does as an enterprise separate from individual sciences like physics or psychology (1934a/1937, §72). Investigations into how beliefs are justified, say, turn out to be psychological inquiries for Carnap. We are likely to object that this cannot be quite right: epistemology is connected with normative matters, so cannot be handed over wholesale to psychology. But why not, Carnap would respond, doesn’t this depend on the kind of normativity we have in mind? Now Carnap, like Neurath, had no truck with categorical imperatives or categorical normativity of any sort. But if the normativity of epistemology is regarded as hypothetical, if it is not unconditional but conditional, then why should’t epistemology become a special chapter of psychology, concerned with the investigation of the ability of certain cognitive processes to attain a certain result? Carnap, in other words, assigned to science the one part of traditional belief-based epistemology which still made sense to him: non-methodologically solipsist inquiries into information-state management (both individual and collective). Or better: rather than forcibly naturalize philosophical concepts Carnap pointed out that it did not belong into (his new conception of) philosophy in the first place.

If this is right, we need to reconsider Carnap’s 1935 pronouncements on the logic of science in the context of other relevants texts of the period. Made in the course of a short conference talk, they might be found actually to leave certain gaps that, when filled, dispel our puzzlement. For if the preceding paragraph is on the right track, then “the transition from epistemology to the logic of science” cannot mean that epistemology becomes logic of science, but rather, if philosophy becomes logic of science, then epistemology must fall where it may.

3.. The Parameters of the New Program. Let’s begin our clarifications with one last question about Carnap’s rejection of methodological solipsism. What are

20 Even Neurath only ever rejected methodological solipsism, not the use of first person psychological sentences (understood physicalistically); unlike Carnap (1936/37, §20), he even allowed introspective reports as (parts of) protocol statements (e.g. 1932b/1983, 93-94; 1936, 162).

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we to make of the fact, that in the Preface to the second edition of the Aufbau he wrote:

When I read the old formulations today, I find many a passage which I would now phrase differently or leave out altogether; but I still agree with the philosophical orientation which stands behind this book. This holds especially for the problems that are posed, and for the essential features of the method whch was employed. The main problem concerns the possibility of the rational reconstruction of the concepts of all fields of knowledge on the basis of concepts that refer to the immediately given. (1961/1967, v)

In addition to the thesis that “it is in principle possible to reduce all concepts to the immediately given” (ibid., vi), Carnap also affirmed that he now preferred a more Machian solution of the question of the basic relation.21 That does not seem to accord with his previous abandonment of methodological solipsism.22

But there is also the following remark from the same late period in which Carnap formulated an even older insight:

It is an essential characteristic of the phenomenal language that it is an absolutely private language which can only be used for soliloquy, but not for common communication between two persons. In contrast, the reistic and the physical languages are intersubjective. (1963, 869; cf.1936-7, 10)

The insight here is the impracticality, indeed uselessness, of the phenomenalist, that is, methodologically solipsist language for the project of reconstructing the language of science. If it is an “absolutely private” language, then this conclusion is inevitable. (If, however, an intersubjective language is employed without the demand that it be translatable into a phenomenalist language, then the priority of the autopsychological, which Carnap’s earlier methodological solipsism had assumed, is forfeited.) It follows that the use of phenomenal languages in the analysis and possible reform of the language of science cannot be recommended.

Given this moral, what could Carnap still have been in agreement with in his old Aufbau? The answer is that in the Preface to the 2nd edition Carnap envisaged pursuing investigations of the logic of science in a purely theoretical spirit. In this case this meant investigating whether it is possible to develop a language 21 “I should now consider … something similar to Mach’s elements, e.g., concrete sense data, as, for example, ‘a red of a certain type at a certin visual field place at a given time’. I would then choose as basic concepts some of the relations between such elements, for example ‘x is earlier than y’, the relation of spatial proximity in the visual field and in other sensory fields, and the relation of qualitative similarity, e.g., color similarity.” Carnap (1961/1967, vii)22 Likewise he wrote in these later years: “At the present time I prefer not to emphasize the requirement of intersubjective confirmability as much as we used to do previously, but rather to consider it to be of secondary importance. I regard as meaningful for me whatever I can, in principle, confirm subjectively. This statement may be taken as a rough formulation of the principle of empiricism.” (1963, 882, orig. emphasis) Prima facie, it cannot be denied that this passage, together with the one just cited from the preface to the second edition, supports a diagnosis of recidivism on Carnap’s part. What needs to be considered is whether we are forced to conclude this; on this, see Fn. 23 below.

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that has the same expressive power as the physical language but uses as its basic elements only expressions that relate to the given. Most notably, what the Preface to the second edition did not speak of, quite in contrast to the Preface to the first edition, was “questions of the reduction of cognitions to one another” (1928a/1967, xvi). Therein lies the change in his perspective on the Aufbau that the later Carnap here gave expression to.23

We must distinguish therefore between, on the one hand, exploratory language constructions and, on the other, the application of constructed language forms in the explication of contested concepts or in application to concrete epistemological questions—between, in other words, pure and descriptive logic of science. In the Preface to the second edition Carnap spoke as a logician for whom the historical grown forms of the language of science did not constitute limits and who regarded the phenomenal language as one amongst others whose formal properties were to be explored. But as noted, it is highly significant that Carnap did not assign, in this Preface to the second edition, an epistemological task to the methodologically solipsist system of concepts. Instead he stressed that he regarded as “particularly suitable for a rational reconstruction of the concept systems of the empirical sciences” a system which contained “as basic elements physical things, and as basic concepts observable properties and relations of such things” (1961, vii-viii). That, of course, was the physicalistic (or reistic) system first introduced as such in “Testability and Meaning” (1936/37) though it can be seen to have been aimed at by his and Neurath’s talk of the physicalistic language already earlier on. It is evident then that Carnap’s abandonment of methodological solipsism remained intact. To read his remarks as returning to it is far from obligatory—and in light of everything else extremely implausible.24 (After all, Carnap’s abandonment only meant the discontinuation of the employment of phenomenalist languages in the construction of scientific languages for practical use or in their rational reconstruction; they remained available as objects for logical investigations.)25

Note what this explanation of the subtleties of Carnap’s anti-methodological- solipsism stance presupposes: the distinction between, crudely speaking, different categories of the logic of science. This is a distinction Carnap did not make in his brief 1935 lecture, but one that he had made already in Logical Syntax. So we must now survey both the early and later more sophisticated forms of Carnap’s conception of philosophy as metatheory to determine the

23 As can be shown with reference to other aspects too, what the later Carnap said about the Aufbau does not always fully agree with what he did in that work. I cannot stop to consider whether his later remarks are always consistent with each other.24 A similar interpretational challenge is offered by his later remark (see Fn. 21 above) of how the primitive predicates of the observational language are to be conceived of—and it can be answered in a similar fashion. This apparent symptom of individualistic recidivism also need not indicate a return to methodological solipsism. That a phenomenalistic language can be considered empiricist does not mean that it can be employed in the reconstruction of our empirical knowledge. To be sure, one may wonder what should be gained by this, but retreating from the condition of intersubjective testability does notprevent him from declarimg methodological solipsism as impractical and useless as before. 25 See Carnap’s stress on the pragmatic reasons for the choice of physicalist languages in (1932d/1987, 469-470) and (1936/37, 466 and 20).

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place of epistemology in his mature metaphilosophy. To be precise, it is two distinctions and their interrelation that are of importance here: first, the distinction between the “pure” and “descriptive” forms of metatheory and, second, the three-fold distinction among three modalities, as it were, of metatheory conceived in semiotic terms.

We begin with the first of these two distinctions. In Logical Syntax Carnap distinguished “pure syntax” from “descriptive syntax”: “In pure syntax only definitions are formulated and the consequences of such definitions developed. Pure syntax is thus wholly analytic, and is nothing more than combinatorial analysis . . . Descriptive syntax . . . is concerned with the syntactical properties and relations of empirically given expressions.” (1934a/1937, 7) Likewise, what the distinction of pure and descriptive semantics amounts to is that descriptive semantics “describes facts” of a historically given language, “it is an empirical science”. By contrast, pure semantics sets up a “system of semantical rules S” which “constitute … nothing else than a definition of certain semantical concepts with respect to S, e.g., ‘designation in S’ or ‘true in S’”. Pure semantics, unlike descriptive semantics, is “entirely analytic and without factual content” (1942, 11-12). So “pure” means that the theorist is unfettered by any constraints to represent a pre-existing language in its syntactic or semantic relations: she is free to construct ab initio. By contrast, “descriptive” means that the syntactic and semantic relations of an already existing language are to be re-constructed; here the theorist is clearly constrained by facts of existing usage.

Logical Syntax also declared that “philosophy [is] replaced by the logic of science” and that “the logic of science is the syntax of the language of science” (1934a/37, §§72-73, section titles). At the time, Carnap failed to make clear, as we saw, in which part of the logic of science, if any, what kind of epistemology was to be pursued.26 When the dust of reorientation had settled he declared that those theses “changed to the following: the task of philosophy is semiotical analysis; the problems of philosophy concern—not the ultimate nature of being but—the semiotical structure of the language of science, including the theoretical part of everyday language.” (1942, 250) What’s most notable here for our purposes is that semiotic studies has three aspects that are relevant for philosophy: syntax, semantic and pragmatics. And this brings us to the second of the two major distinctions introduced above.

“We can distinguish between those problems which deal with the activities of gaining and communicating knowledge and the problems of logical analysis. Those of the first kind belong to pragmatics, those of the second kind to semantics or syntax—to semantics, if designate (‘meaning’) are taken into consideration; to syntax, if the analysis is purely formal.” (ibid.)

26 Prior to his Paris lecture he had only remarked on this that “[t]he term ‘logic of science’ will be understood by us in a very wide sense, as meaning the domain of all questions which are usually designated as pure and applied logic, as the logical analysis of the special sciences and of science as a whole, as epistemology, as problems of foundations, and the like (in so far as these questions are free from metaphysics and from all reference to norms, values, transcendentals, etc.)” (1934a/37, 280-281).

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As a result, what Carnap designated with the short-hand “logic of science” in 1935 actually splits into six departments: two each (“pure” and “descriptive”) of syntax, semantics and pragmatics. And fittingly, by 1942 Carnap had also renamed what he once called “logic of science” as “theoretical philosophy” (1942, 245), but this was no mere renaming but also signaled a further broadening of approach: both pure and descriptive logic of science had been enriched with pragmatics.27

For present purposes it is the often overlooked innovation that in due course came with Carnap’s semiotical turn that is of importance: his acceptance of pragmatics as dealing with “the action, state and environment” of speakers or hearers (1939, 4).28 As we just saw, by 1942 he distinguished between two types of problems with which theoretical philosophy was concerned: “problems which deal with the activities of gaining and communicating knowledge” and “problems of logical analysis” and assigned the first to pragmatics. Carnap’s broadening of approach held out the promise, therefore, to incorporate something more like what had previously been considered epistemological inquiries.

To begin to see the pay-off, let’s return to the question of the disciplinary location of the choice between of methodological solipsism and physicalism. It is clear that the distinction between pure and descriptive logic of science allowed explorations of phenomenal languages to take place in pure syntax and/or semantics. This was the case even before the admission of pragmatics into theoretical philosophy. In Logical Syntax, of course, Carnap had already made clear that the investigations of the logician of science were also to have a practical pay-off (1934a/1937, §86). Just how they could do so remained a little bit vague, however. Yes, they now offered proposals for the syntactic and soon for the semantic form of the language of science—but just who was it, institutionally speaking, that investigated and assessed these proposals? Yes, the issues involved were clearly applied or descriptive—but could their concern with practical utilities and empirical facts be accommodated within the logic of science as it had been conceived so far? Inquiries into the utility of language users, for instance, hardly fit into that earlier conception.

Integrating such inquiries required complementing the logic of science with something that in later years Phillip Frank called the “pragmatics of science” (1957/2004, 360) and that Neurath already in the mid-1930s called the “behavioristics of scholars” (1936/1983, 160, 169), but that was excluded in Logical Syntax from the logic of science and included only in the wider “theory of

27 To be sure, the metatheorical terminology changed, but the architecture of what Uebel (2011) and (2015) called the “bipartite metatheory conception” was retained. The latter’s distinction between “the logic of science” and “the pragmatics of science” translates approximately into that between “pure” and “descriptive” logic of science, i.e. once the enrichment of the latter by pragmatics is taken into account (see the last paragraph of this section). The enrichment provided amounts to what Carus describes as the addition of a feedback loop which provides utility information for proposals to revise the logico-linguistic frameworks developed or described by the logic of science; see his (2017) for further development of Howard Stein’s discernment in (1992) of what is aptly called a “dialectic” between Carnap’s semantics and pragmatics.28 For some discussion of the history of Carnap’s embrace of pragmatics, see Uebel (2013).

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science”: the empirical metatheories of psychology, sociology and history of science (1934/1937, §72). In the mid-1930s Carnap had to defer to colleagues in empirical metatheoretical disciplines to issue recommendations about the actual adoption of the proposals made by him as a logician. But by the early 1940s, such inquiries were designated by Carnap as pragmatics, and belonged to his broad semiotic conception of “theoretical philosophy.” Descriptive pragmatics handled concrete empirical investigations while pure pragmatics developed the analytic conceptual framework for doing so. And—putting our concern to rest—proposals for the construction of the language of science along strictly physicalistic lines were advanced in pure pragmatics.

4. The Place of Epistemology in Carnap’s Metaphilosophy. We are now in a position to determine the place of epistemology in Carnap’s mature metaphilosophy. Richard Creath has argued that the linguistic structures which Carnap’s logic of science represents as networks of deducibility relations can also be regarded as fact structures of justification once they are linked to observation statements. Regarded thus their investigation replaces the “properly philosophic parts of traditional epistemology” (1994, 290; cf. 1992, 146).29 Let’s consider how this works.

Carnap determined the cognitive content of a sentence in terms of its non-analytic consequences. Now as Creath points out, the relation of consequence in particular “corresponds to the causal or evidential relation between thoughts in functionalist theories of mind” (1994, 289). On account of this correspondence we can speak of the inferential role of a sentence which for Carnap constituted its meaning in his early logic of science, and in this respect Carnap’s syntactic theory of meaning can serve epistemological purposes.30 Note also that Carnap’s turn to semantics did not obliterate these logical relations, so they remained available for the logic of science to exploit. It did so only, of course, in the extremely impersonal fashion of providing propositional justification that we discussed above (§1): the epistemic subject as such does not figure in this theory. The impersonal investigations allowed do not take on all the tasks that commonly are assigned to epistemology, so their pursuit has not yet been restored to the later Carnap in full.

For a doxastic justification of knowledge claims, the sentences in question must be understood as representing the content of individual beliefs. To investigate these matters we have to turn to what Carnap once called “the wider domain” of “the ‘theory of science’” which he distinguished from the logic of science proper (1934a/1937, §72, 279). By 1942, as we saw, such empirical issues were recognized within his semiotic conception of theoretical philosophy and he characterized them as follows:

29 It is here that Creath’s disagreement with Dreben, noted in my introduction, is located.30 In later years, Carnap warned against the equation of evidence and meaning—“the observational evidence which a person may or may not have for his belief in a statement describing a physical situation, is not part of the meaning of this statement” (1963, 1007)—but this does not tell against a notion of inferential role that fixes meaning by the logical relations of the expressions involved to all others and so provides a variety of potential evidential relations.

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They occur especially in the theory of knowledge and the philosophy of science. If construed as problems of semiotic, they belong to pragmatics. They have to do, for instance, with the activities of perception, observation, comparison, registration, confirmation, etc., as far as these activities lead to or refer to knowledge formulated in language. (1942, 245)

Clearly, the expression “activities that lead to or refer to knowledge formulated in language” gave the license to gather a wide variety of human activities under the heading of pragmatics. Carnap was very open towards such a pragmatics of science, and while he did not pursue such inquiries very far himself, he now accepted them into “theoretical philosophy”. What distinguishes descriptive pragmatics from descriptive syntax and semantics is that it allows reference to psychological (as well as sociological, economic, cultural, evolutionary, etc.) states of affairs.

The pragmatics of science can pay attention to what the syntax and semantics of science must neglect. Pragmatics as an empirical science can deal with epistemological questions aiming at actual beliefs and their preconditions. Pure pragmatics may propose normative or meta-normative frameworks for rationality in general, or more detailed analytical schemata to explicate and assess relations between different conceptual elements in interpersonal interpretation as well as in the assessment of knowledge claims. Importantly, these frameworks use variables that stand for decision-making agents and users of language (along with all the other variables that pure syntax and semantics use): these are the place-holders for the epistemic subjects which the old logic of science could not consider. Descriptive pragmatics then fills in these variables with referring expressions.

It is clear then that non-methodologically solipsist epistemology can find a place on the empirical wing of Carnap’s semiotic conception of theoretical philosophy. This fits very well with Carnap’s own minimal suggestions in this direction, like his determination in “Testability and Meaning” that terms as crucial for his account of the empirical nature of the language of science as “observable” and “testable” are terms the definition of which depends on psychology (1936-37, 454). In other words, when it comes to accounting for the actual knowledge claims of science Carnap was more than prepared to be naturalistically minded (very much along the lines drawn at the end of §3 above). To the limited extent that he engaged with such questions he was himself already practicing what nowadays is known as naturalistic epistemology and joining his colleagues who made such pragmatic investigations their speciality. Neurath’s theory of protocol sentences which provides nested sets of acceptance conditions for observational testimony in science as a replacement for vainly sought for phenomenalist foundations and Frank’s investigations of the role of “extra-scientific reasons” in theory acceptance across history provide characteristic examples of the kind of pragmatics of science Carnap did not pursue himself but the need for which he fully recognized.31

31 See Neurath (1932b) and Frank (1956), (1957/2004, 354-360) and Uebel (2009) and (2000) for discussion.

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A question that arises when it is asked whether the pragmatics of science can shoulder the normative task of epistemology is thus equivalent to the question whether naturalistic epistemology can do so and the answer to this is clearly positive. The normativity of naturalistic epistemology is not an unconditional one, of course, but an instrumental one: given the determination of an end, the determination of the means to achieve it is an empirical matter.32 To be sure, any such epistemic assessments are dependent upon what can only a conventional determination of ends (Carnap opted for empirical adequacy). Yet worries about the merely conventional nature of epistemic ends are pointless, given that the task of philosophy, we recall, is that of offering proposals for how to conceive of our own cognitive enterprises. Insofar as only conditional normativity is required for this, pragmatics of science remains suitably empirical. (Needless to say, this leaves certain questions about normativity to be dealt with in pure pragmatics.)33 5. Conclusion. Carnap and Neurath belong to the first thinkers within the horizon of European and American philosophy who argued sustainedly against the basic assumptions of the traditional conception of knowledge shared by rationalists and empiricists alike. Of interest here is less the tradition’s craving for incorrigibility and certainty of knowledge (however important this was historically speaking) but its individualism. Methodological solipsism gives expression to this epistemological individualism in discounting intersubjectivity as a condition of cognitive activity. It is interesting (but cannot be explored further here) that each of Carnap and Neurath reached this result in their own fashion: both managed their overcoming of this individualism with arguments of their own.34

Carnap’s and Neurath’s cooperation was not always harmonious and in their theoretical emphases they often differed, but in their goal they always agreed. This goal is mirrored in Carnap’s metaphilosophy. By requiring philosophy to become first the logic of science and later the semiotic analysis of the language of science he determined its task to develop tools for the analysis and construction of linguistic and conceptual frameworks—of linguistic forms and conceptual spaces. But this was never an end in itself but possessed its own pragmatic horizon. Already in the so-called manifesto of the (left) Vienna Circle of which

32 That Quine’s form of naturalistic epistemology deals with the issue of normativity in this fashion is well documented in (1986). That Neurath endorsed a conditional view of epistemic normativity was argued in Uebel (1996). 33 Carnap himself did not offer an explicit discussion of the conditional nature of epistemic normativity, yet, given both his strong empiricism and his ethical noncognitivsm (see 1963, 999-1007 and 2017), it is difficult to see how else he could have conceived of epistemic normativity. It does not follow, however, that Carnap’s general conception of rationality was exclusively instrumentalist for he also allowed, tolerantly without endorsing it, Wertrationalität; see Carnap (2017) and the discussion in Carus (2017).34 It would be mistaken to say that Neurath had the motivating intuition, Carnap the effective arguments. Neurath possessed good arguments of his own for his opposition to epistemological indvidualism (his private language argument was considerably more radical than Carnap’s). That it was not his arguments that ultimately convinced Carnap to abandon methodological solisipsism was due to the fact that Carnap thought they only told againt a type of philosophy he did not subscribe to (any longer).

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Carnap was a signatory we can read: “intellectual tools of modern empiricism are to be developed, tools that are also needed in forming public and private life.” (Verein Ernst Mach 1929/2012, 81)35 Importantly, Carnap’s logicians of science served not only as the underlaborers of science, but also as its epistemic conscience. (This normative concern was intrinsic to the subject matter—knowledge—and did not need not be imported.)

Perhaps even more importantly, the intention which motivated Carnap’s metaphilosophy was not that of domesticating human intelligence by means of logic, but to broaden and liberate it and allow it to think what had not yet been thought. Logic was conceived of not only as an instrument for the analysis of what is given but also as an instrument of construction—as the manifesto just cited stressed repeatedly: “we have to fashion intellectual tools for everyday life, for the daily life of the scholar but also for the daily life of all those who join in working at the conscious reshaping of life.” (Ibid.) Joining pragmatics to semantics and syntax in his semiotic conception of theoretical philosophy made sure that what Carnap had always regarded as a complement to his austere logic of science was an official part of his and his friends’ philosophy.

In conclusion it may be added what is all too often forgotten, namely, that it was part of Carnap’s metaphilosophy to respond to the demand on critical theories ever since the nineteenth century to call into question “ideologically frozen relations of dependence that can in principle be transformed”.36 To be sure, Carnap’s philosophy addresses such questioning only on the abstract level of conceptual relations of dependence and with regard to questions of theory development and choice—but all alternatives first have to be thinkable, thought of and thought through before their realization is attempted. From his base “on the icy slopes of logic” (ibid., 90) Carnap sought to provide tools for use in practical and concrete contexts. His was no longer a theory of knowledge in the traditional sense: far from taking a spectator’s point of view, Carnap’s project of providing for analyses of logico-linguistic frameworks was meant to enable investigations of scientific metrology as much as critiques of social ideologies in the spirit of Enlightenment.37

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35 In fact, this was a quotation from handbill “An alle Freunde wissenschaftlicher Weltauffassung!” advertising the Verein and reprinted in the original brochure (see Verein Ernst Mach 1929/2012, 60).36 The quotation is taken from the early Habermas (1965/1972, 310). For more on the “critical” potential of Carnap’s metaphilosophy, see Carus (2007, Ch. 11).37 I wish to thank the editor of this issue for numerous comments and suggestions which greatly improved this paper. Some differences between our readings of Carnap remain, however, and he should not be held responsible for whatever I have committed here.

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