Felix Kaufmann, Review of Rudolf Carnap’s Logische Syntax der Sprache (1937)

Felix Kaufmann’s journal book review presents Carnap’s Logische Syntax der Sprache as a major contribution to the methodological criticism of philosophy, with particular relevance to the social sciences. Its starting point is the prevalence of appeals to a priori insight in sociology, economics, and historical inquiry: disputants invoke allegedly self-evident principles to establish the exclusive legitimacy of their preferred methods. Mathematics and logic have traditionally supplied the authoritative examples supporting such appeals. Kaufmann argues that advances in geometry, axiomatics, and symbolic logic have undermined older interpretations of that authority, thereby weakening philosophical doctrines dependent upon them. Carnap’s book, alongside Wittgenstein’s Tractatus, represents an especially important development of this critical movement.

Kaufmann explicitly limits his review to Carnap’s philosophically consequential theses, leaving aside the detailed logical investigations that occupy most of the book. His exposition proceeds from the definition of syntax and calculus to the distinction between scientific and philosophical problems, then to the translation of apparently object-directed statements into statements about language. It culminates in Carnap’s principle of tolerance and Kaufmann’s qualified endorsement. The organizing thesis is that scientifically legitimate philosophy becomes logical analysis: empirical questions belong to the relevant sciences, while the remaining task is to examine their concepts, propositions, and theories.

Syntax, in this expanded sense, studies the kinds and sequences of signs without considering their meanings. Rules of formation specify admissible expressions; rules of transformation specify permissible transitions between expressions. Logical inference thus becomes part of syntax rather than a separate discipline grounded in privileged insight. The chess analogy makes the conception accessible: pieces function as signs, positions as configurations, and moves as rule-governed transformations. Kaufmann then distinguishes the formal investigation of possible arrangements from the empirical investigation of actual expressions:

In pure syntax only definitions are put forth and implications deduced from them. Hence, it is analytical throughout. It is nothing other than combination, or, if you will, geometry of finite discrete sequences of a certain kind.

This characterization locates necessity within definitions and their consequences. Descriptive syntax, by contrast, investigates perceptible expressions, such as sentences printed in a particular book. Its relation to pure syntax resembles that of physical to mathematical geometry. The distinction matters because it separates the construction and exploration of formal systems from claims about their empirical realization; neither requires the traditional philosophical appeal to a priori intuition.

The next conceptual move distinguishes questions about objects from questions about the sentences and theories through which objects are investigated. Zoology concerns animals and their relations, while the logic of zoology concerns its sentences, concept formation, hypotheses, and theories. Carnap applies this distinction to philosophy. Claims about transcendent entities or absolute norms are treated as pseudo-sentences expressing emotions rather than theoretical knowledge. Genuine questions about objects are reassigned to the special sciences, particularly psychology. Kaufmann summarizes the resulting redistribution of intellectual work:

Outside the genuine special sciences the only valid scientific problems are those relating to the logical analysis of science, of its sentences, its concepts, theories, etc. Let us call this complex of problems collectively, "Logic of science." Logic of science, however, is the syntax of language of science.

The argument therefore removes both metaphysics as a special domain and philosophy’s claim to a distinctive standpoint above the sciences. Yet it preserves methodological inquiry by reformulating its questions. A crucial intermediate category consists of pseudo-object-sentences: statements that appear to concern things but actually concern the forms used to describe them. Carnap’s passage from the material to the formal mode of language makes this displacement explicit. A statement that yesterday’s lecture concerned Babylon becomes a statement about the occurrence of a word or synonym; a report of what Karl said becomes a statement about an uttered sentence or its consequences.

Kaufmann also stresses Carnap’s demonstration that a language can make statements about itself through its own expressions. He presents this as a significant departure from the contrary position associated with Russell’s theory of types and especially Wittgenstein. Its broader philosophical importance lies in making linguistic analysis available within language rather than assigning it to an inaccessible standpoint outside expression.

For Kaufmann, the decisive conclusion is the rejection of a priorism. A language comprises conventions assessed for compatibility and usefulness, not assertions that can themselves be true or false. The demand for a uniquely correct logic consequently gives way to explicit construction and accountable comparison:

Carnap formulates this "principle of tolerance" in syntax as follows: "In Logic there is no moral. Each may build his logic, i.e. his language-form, as he likes. Only, if he would discuss with us, he must indicate clearly how he intends to build it, and give syntactical rules instead of philosophical explanations" (p. 45).

Tolerance here is disciplined by the requirement to state rules clearly. Carnap expects this replacement of philosophical explanations by precise formulations to enable fruitful collaboration on scientific methodology. Kaufmann does not fully share his fundamental position and declines to undertake a detailed critique in the review. His final assessment nevertheless distinguishes disagreement from the book’s value as a basis for debate:

To my mind it provides the best basis, up to the present, for a radical discussion of the theses of modern (logical) Positivism.

The review’s relevance lies in this combination of reconstruction and reserve: it introduces social scientists to a powerful alternative to intuition-based methodological controversy while leaving Carnap’s comprehensive reduction of scientific philosophy to syntax open to critical discussion.