Both books form part of the proceedings of a 2001 Vienna conference held to mark the tenth anniversary of the Vienna Circle Institute (VCI). Founded independently of the University of Vienna (and funded even more precariously) and led since its inception by Friedrich Stadler, the VCI has managed to organize and cosponsor a remarkable number of conferences, most of them documented by volumes in three ongoing series of monographs that have become important repositories of current work on the legacy of logical empiricism: Veröffentlichungen des Instituts Wiener Kreis, Yearbook of the Vienna Circle Institute, and Vienna Circle Institute Library. While some of these previous conferences and volumes also addressed entirely contemporary themes (game theory, quantum physics), the titles of the present volumes indicate that they are anchored historically, with some contributions moved mainly by current concerns. The Stadler volume surveys the conference as whole except for the (further elaborated) contributions on Carnap, which are collected in the Bonk volume. It provides an excellent service in showcasing the very varied and wide-ranging work that is currently being done on the Vienna Circle and what Stadler, somewhat expansively, calls its ‘periphery’. Here I can only indicate the breadth of topics treated of in his volume and make some highly selective remarks on some of the Carnap papers in Thomas Bonk's volume. (Apologies if the first part sounds like a list: it is one.)

By way of an introduction to The Vienna Circle and Logical Empiricism. Re-evaluation and Future Perspectives, Stadler starts off with a compact summary of the trends discernible in recent work on the Vienna Circle and signals what he considers to be outstanding questions.

The section “Origins and History” offers reflections on the pluralism of tenable world views by Arne Naess (once a visitor to the Vienna Circle) and on Bolzano's account of justification by Anita von Duhn, while Paolo Parrini helpfully discusses the subtle question of what distinguishes the mature logical empiricism of Schlick and Reichenbach from Schlick's own Allgemeine Erkenntnislehre, and David Hyder analyzes the long-overlooked Kantian metaphysics of Hertz's Mechanics.

The section “Moritz Schlick” begins with Hubert Schleichert showing, with the example of Schlick's idea of nonterritorial states, that in the Vienna Circle political utopian thought was by no means limited to Neurath. Massimo Ferrari provides an analysis of Schlick's long-neglected reviews for the Vierteljahrschrift für wissenschaftliche Philosophie from 1911 to 1916, giving important insights into his thinking in the period leading up to Erkenntnislehre. Hans-Jürgen Wendel then compares Schlick's use of the verifiability criterion as both a meaning and a demarcation criterion with Kant and Popper, while Dagmar Borchers looks approvingly at Schlick's metaethics from the perspective of virtue ethics.

The section “Hans Reichenbach” contains Carsten Klein's and Robert Rynasiewicz's critical analyses of Reichenbach's uses of coordinative definitions and of definitions of simultaneity, respectively.

In the section “Other Proponents and Periphery,” Juha Manninen provides new materials concerning the inception of physicalism by way of an analysis of Neurath's earliest version of Empirical Sociology (which Schlick rejected), while Wolfgang Huemer revisits Felix Kaufmann's attempt to combine logical empiricism and phenomenology, and Artur Koterski reconstructs Bela von Juhos’ concept of Konstatierungen. The section concludes with Paolo Mancosu and Mathieu Marion redeeming Wittgenstein's reputation as a mathematician by reconstructing his constructivization of Euler's proof of the infinity of primes and Graciela DePierris’ critique of Quine's characterization of the development of traditional epistemology in “Epistemology Naturalized,” arguing that his program cannot be legitimated in this way.

In the section “Unity and Plurality,” Elliot Sober discusses two uses of the principle that explanation of similar phenomena should be unified, and argues that while scientific explanation as such holds no favor for unified accounts, abductive explanations do. Christopher Hitchcock considers the role of unity in philosophical theory choice illustrating how different concepts of causation (causation along a particular route and net causal effect) can be accommodated within the same theoretical framework. Diederick Raven revisits Edgar Zilsel's concern to establish (statistical) laws in history and sociology.

In the section “Contexts of Science,” Gregor Schiemann criticizes Reichenbach's distinction of the contexts of discovery and justification as a misleading approach to conceptual questions, Giora Hon argues that only attention to historical context allows for a theory of experimental error, and Jutta Schickore offers reflections on the relation between general epistemology and philosophy of science on the issue of the justification of scientific theories.

In the sections “Epistemology” and “Ethics,” Daniel Conitz defends the method of thought experiments against recent criticisms, F. O. Engler provides an interpretation of Niels Bohr's philosophy of physics as a version of structural realism, and Uwe Czaniera defends noncognitivist metaethics against the immorality reproach.

The last two sections return exclusively to historical concerns. Under the heading “Women of Logical Empiricism,” Susan Stebbing figures twice: once in Michael Beaney's paper on her contribution to the theory of philosophical analysis and once in Nikolay Milkov's assessment of her criticism of Wittgenstein's Tractatus. Dagmar Borchers considers the contributions by Else Frenkel-Brunswik to the scientific understanding of the theory of psychoanalysis, while Adelheid Hamacher-Hermes provides new findings on the work and life of Rose Rand. In the final “Documentation” section, Olessia Nazarova chronicles the fate of logical positivism in the Soviet Union; it emerges that even sympathetic treatments of it took their start from incorrect interpretations as phenomenalist foundationalism.

The papers in Thomas Bonk's volume can be divided into historical and systematic ones, though given Carnap's undiminished—indeed, resurgent—attraction for analytic philosophy of science and epistemology, this division is often highly attenuated. Among the more historical papers count those by Thomas Mormann, Ulrich Majer, and C. Wade Savage on Carnap's Aufbau, Chris Pinnock's on Carnap's understanding of the doctrine of the unity of science, Sahotra Sarkar's on the importance of Husserl's role in Carnap's dissertation Der Raum, and Jan Wolenski's on Carnap's metaphilosophy. Among the more systematically oriented papers count Ilka Niiniluoto's on Carnap on truth, Jaako Hintikka's comparison of the Vienna Circle with current logic and epistemology, and those by Graham Bird, Wolfgang Spohn, and Bonk himself on, respectively, Carnap's arguments for the distinction between internal and external questions, on the analysis of dispositions in light of the dispute between Carnap and Quine, and a defense of Carnap against Barry Stroud's criticism of his antiskeptical moves.

Niiniluoto's essay provides a compact but comprehensive overview of Carnap's work on logical syntax and semantics (including a comparison with the work of Tarski). As can be expected from one of the stalwarts of scientific realism, Niiniluoto is uncomfortable with Carnap's admittedly difficult rejection of both realism and antirealism. Thus he employs Carnap's 1935 recognition that the semantic account of truth is compatible with the linguistic relativity of facts to argue that Carnap's internal-external distinction is redundant, clearing the way for a correspondence-theoretical realism. One issue here, however, is whether this does not overlook that Carnap embraced the pluralist view of logic as calculus against the background of the language as universal medium conception of his predecessors. The combination of the conception of logics as more or less partial constructed calculi with a universalist conception of the background language into which we must perforce acquiesce would block Niiniluoto's assimilation of Carnap to scientific realism and correspondentism and redeem the internal-external distinction.

Wolenski's investigation of Carnap's metaphilosophy concentrates on the syntactic phase and throws into relief that much of its point consisted in overcoming the perceived limitations of Wittgenstein's Tractarian philosophy. Unlike many recent commentators, Wolenski draws a sharp contrast between the syntactic and the semantic Carnap, whose tension seems irresolvable: on the one hand, Carnap's syntactic metatheory collapsed due to internal difficulties’ on the other hand, his accommodation of the rise of semantics led to reformulations of his metaphilosophical claims in Introduction to Semantics that are “too general to be convincing” (41). Wolenski leaves unanswered the question whether Carnap's distinction of internal and external questions makes for a sustainable successor to the overambitious antimetaphysical claims of his syntactic period, however.

Mormann, Majer, and Savage all present contrasting interpretations of the Aufbau. Majer argues for the central importance of Gestaltheorie in the Aufbau, but concedes the inability of its holism to rescue its constitution system on an autopsychological basis. Mormann takes issue with this, and by contrast, argues for the importance of synthetic geometry for the work of the early Carnap, especially for his development of quasi analysis which can, he stresses, survive Goodman's and Quine's criticisms. As a result of this geometric reading—and of a further generalization of the method of quasi analysis beyond Carnap's own “anemic characterization” of it—the Aufbau is said to emerge as “more than a monument of the philosophical past” (61–62). Savage meanwhile takes his cue from Carnap's remarks in the Preface to the second edition of the Aufbau which, notoriously, speak of it in an unabashedly phenomenalistic fashion. His proposal to rehabilitate Carnap's constitution theory turns on recognizing that nondefinitional ways of introducing terminology must become part of its repertoire and he points to the advantage of ‘coordinations’: they codify operational instructions to form representations under specific conditions only. Clearly, these readings of the Aufbau cannot coalesce in one and the same model, but each casts light on often neglected aspects of Carnap's work.

Pincock's discussion of Carnap's conception of the unity of science between 1921 and 1928 usefully differentiates the concepts of a construction (or constitution) system and of a construction (or constitution) theory, with the former denoting a structural taxonomy and a derivational genealogy of concepts and the latter a general theory of such conceptual systems. Now the unity of science simply means the comprehension of all scientific concepts in one such construction system. This minimalist conception is very liberal in that it requires of the different sciences neither a shared methodology nor a shared ontology; on the other hand, it goes considerably beyond Schlick and Reichenbach in obviating recourse to coordinating definitions and their appeal to nonstructural properties and upholding the monism of structural descriptions. One may note that this reconstruction makes the ‘foundedness’ problem of the Aufbau all the more acute.

Both Bird and Bonk are concerned with recent criticisms of Carnap's reasoning by leading contemporary epistemologists. Bird argues, first, against Susan Haack's claim that Carnap offers three nonverificationist, but nevertheless faulty, arguments for the distinction of internal and external questions. In doing so, he reads Carnap as arguing, not that no clear interpretation of suspect philosophical or metaphysical propositions could be given, but only that so far none has been given. (The volume also reprints Bird's earlier “Carnap and Quine: Internal and External Questions,” which sought to disarm Quine's criticisms of Carnap on a similar basis.) Second, against Barry Stroud's criticism of Carnap's distinction, Bird argues that his antiverificationist argument rests on an unwarranted appeal to Carnap's earlier views in Scheinprobleme of 1928. Bonk pursues a related issue: Stroud's assessment of Carnap's twofold ‘response to the sceptical problem’, an older ‘negative’ one in Scheinprobleme, and the ‘positive’ one of “Empiricism, Semantics and Ontology” (Stroud's terms). Bonk argues that already in 1928, Carnap held a truth-conditional theory that differed from Wittgenstein's and Schlick's verificationism (against which Stroud's arguments would work), but he concedes that Carnap's ‘negative’ argument does not disarm all forms of skepticism. Against Stroud's second argument, Bonk argues that it rests on a false dilemma (idealism versus realism) in that Carnap's frameworks must neither explain how empirical knowledge is possible nor explain the invariance of experiential content in the admissible rational reconstructions. Like Bird, Bonk helpfully defends Carnap against charges of incoherence. It is to be wondered, though, whether Carnap was seriously concerned with skepticism to begin with: after all, his ‘logic of science’ sought to overcome traditional epistemology. Accordingly, Carnap's internal-external distinction is perhaps better read as a reasoned refusal to engage with skepticism rather than a move within the dialectic of claim and refutation.

Even though it has been impossible to discuss all the papers in this volume—I had to leave out Hintikka's, Sarkar's, and Spohn's interesting contributions—it will be evident already that there is much material here to help reflection about Carnapian doctrines that are much discussed again of late. With different authors taking clearly conflicting stances, the complexity of the issues is highlighted well. To the new literature on Carnap, this volume makes a distinctive and valuable contribution.