Felix Kaufmann, Unified Science (1939)

Felix Kaufmann’s review essay assesses the early installments of the International Encyclopedia of Unified Science as both a philosophical undertaking and an institution of scientific cooperation. Moving from the Vienna Circle’s intellectual background through the encyclopedia’s organization and individual contributions, it concludes with a qualified endorsement. Kaufmann supports clarification of the relations between sciences but disputes the assumption that this task requires physicalism or an exclusively logical conception of philosophy. His central distinction is between the value of a shared enterprise and the adequacy of its guiding doctrines: criticism should help develop the encyclopedia rather than obstruct it.

Kaufmann locates the Unity of Science Movement in the Vienna Circle, identifying Schlick, Hahn, Carnap, and Neurath as its intellectual leaders while emphasizing differences among its members. Their common empiricism distinguished empirical statements from logico-mathematical tautologies and assigned philosophy the logical analysis of scientific propositions, concepts, and methods. Symbolic logic supplied an instrument for this analysis, which also served to expose metaphysical statements as meaningless. Kaufmann traces influences from Hume, Russell, Wittgenstein, Mach, and Poincaré without presenting the movement as doctrinally uniform. Physicalism became dominant only later and remained contested:

This doctrine does not maintain that all the phenomena treated in the sciences of biology, psychology and sociology can today be explained by the laws of physics, but it does claim that all biological, psychological and sociological concepts can be reduced to physical concepts.

The distinction between explaining phenomena through physical laws and reducing concepts to physical concepts prevents an overly simple reading of the program. Kaufmann also connects its critique of metaphysics with the Circle’s progressive politics and opposition to reactionary ideologies. International contacts, including those with American pragmatists and behaviorists, widened the movement’s constituency. The practical impetus was to clarify disciplinary relationships, eliminate terminological discrepancies, and enable researchers and students to follow developments outside their specialties.

Neurath’s encyclopedia gives this cooperative ambition an organizational form. Kaufmann describes its projected construction through the editor’s onion metaphor: twenty foundational pamphlets would constitute the heart, followed by volumes addressing systematization within particular sciences and across science as a whole, then further layers devoted to specialized problems. An analytical index would make the monographs usable as a reference work. Crucially, scientists holding different views would present unresolved difficulties and disagreements. The architecture therefore promises an organized encounter among approaches, not merely a finished statement of consensus.

The review then examines the published contributions. The opening brochure joins Neurath’s account of the enterprise to Bohr’s discussion of analysis and synthesis, Dewey’s treatment of scientific unity as a social and pedagogical problem, Russell’s discussion of logical form, Carnap’s argument for unity, and Morris’s account of scientific empiricism. Kaufmann particularly values Dewey’s attention to cooperation and public understanding. He recognizes Carnap’s central contribution while maintaining that both philosophy as logical syntax and the arguments for physicalism require revision; he also notes that Carnap’s physicalism has become less radical.

The subsequent monographs make the breadth and pedagogical demands of the project concrete. Morris’s theory of signs offers a behavioristic account without explicitly addressing psychic factors. Lenzen’s study of empirical procedures concentrates on physics, discussing measurement and the observation of microscopic entities. Nagel’s treatment of probability receives especially strong praise for combining applications and history, the calculus and competing interpretations, and methodological questions. Its achievement is to interest specialists while giving attentive nonspecialists a coherent understanding. Kaufmann formulates the standard that other contributions should meet:

Each reader should be enabled to obtain a coherent view of the problems dealt with, even if he cannot understand every detail.

Accessibility here means intelligibility across disciplinary boundaries, not the removal of technical substance. Carnap’s Foundations of Logic and Mathematics clarifies earlier formulations and provides an important introduction to his larger work, but Kaufmann fears that its mode of reasoning will remain unfamiliar to many readers. A historical introduction to formalization might help. Bloomfield’s account of linguistics is likewise valuable as specialist exposition, while its philosophical criticisms of apriorism, mentalism, and solipsism warrant caution.

These judgments culminate in Kaufmann’s methodological objection:

As I have already said, I cannot endorse the physicalistic doctrine, and furthermore I believe that the logical empiricists, in their laudable efforts to do away with metaphysical pseudo-problems, have often made such violent use of Occam's Razor that many real problems have also been cut away.

His concern is that selecting problems and unifying terminology may suppress important questions or interpret them inadequately. He shares the conception of philosophy as analysis of experience but refuses to restrict that analysis to logic in the strict sense. Scientific unity remains a legitimate task even when its current philosophical formulation is insufficient.

The conclusion converts this reservation into a principle of participation:

The best way for fellow scientists to help is by presenting their suggestions and criticisms.

Kaufmann calls for sustained discussion around the encyclopedia as it develops. General uncertainty makes ambitious intellectual cooperation more necessary, not less timely. The essay’s significance lies in this defense of unity through criticism: an undertaking can deserve support because it facilitates methodological clarification and exchange, while remaining answerable for what its organizing concepts leave out.