(Student Guide to World Philosophy)

Rudolf Carnap’s Philosophy and Logical Syntax is the substance of three lectures that he gave at the University of London in 1934. As a result, the book is short, outlining the essentials of the logical positivism of the Vienna Circle from the viewpoint of probably the best known and perhaps the most influential member of the group.

Logical positivism had its origin in a seminar conducted in the 1920’s by Moritz Schlick at the University of Vienna. A number of the members of this group, the original Vienna Circle, were scientists reacting against those idealist philosophers who pontificated, sometimes in almost complete ignorance, about the aim and function of science. Part of positivism’s program was the explicit rejection of this kind of irresponsible philosophizing. Another characteristic concern of the group was a strong interest in logic, an interest that grew out of its members’ admiration for the work that had been done on the foundations of mathematics toward the close of the nineteenth century and in the early twentieth century, particularly the work of Alfred North Whitehead and Bertrand Russell in their Principia Mathematica (1910-1913). These interests quite naturally led the Vienna group to deliberate regarding philosophy’s proper business. They decided that philosophy is properly the analysis and clarification of meaningful language. By meaningful language, they meant the language of empirical science together with the language of mathematics; all other language, they held, lacked cognitive meaning. The Vienna Circle philosophers gave expression to this conviction in their criterion of empirical meaning, a widely known and vigorously debated tenet of logical positivism.

Verifiability Criterion

(Student Guide to World Philosophy)

Carnap spends the first chapter of Philosophy and Logical Syntax discussing the implications of the verifiability criterion. At one point he states that only the propositions of mathematics and empirical science “have sense” and that all other propositions are without theoretical sense. However, he does not do much with mathematical propositions—with “analytic” propositions, as positivists sometimes labeled the propositions of logic and mathematics. He spends most of his time with “synthetic” propositions; that is, with propositions whose truth value cannot be determined simply by referring to their logical form. As examples of this analytic-synthetic distinction, consider the two propositions: “The ball is red,” and “Either the ball is red or the ball is not red.” One cannot know whether the first one is true or false without in fact examining the ball, but one can know that the second proposition is true without looking at the ball. It is true by virtue of its logical form. A sentence that is true or false by virtue of its form alone is analytic; a sentence whose truth value is determined by the (nonlinguistic) facts is synthetic.

Carnap holds the view that the only synthetic propositions that make sense are those propositions whose truth value can be determined by consulting the evidence of sense. These propositions, he further believes, are all to be found within the domain of empirical science. He uses the word “verification” in the usual logical positivist sense; that is to say, a proposition is verifiable if its truth value can be determined by reference to sense experience. The only synthetic propositions that make sense, then, are verifiable propositions, and these are all scientific propositions. This is the verifiability criterion of empirical meaning.

A Definition of Philosophy

(Student Guide to World Philosophy)

It is Carnap’s view, then, that philosophy is the logical analysis of meaningful language, and meaningful language is restricted either to analytic propositions (logic and mathematics) or to empirically verifiable propositions (natural science). This theory implies that certain traditional areas of philosophy are no longer to be regarded as legitimate. Carnap rejects what he calls traditional metaphysics because it is made up of propositions that he feels are neither analytic nor empirically verifiable. As examples of metaphysical sentences, he mentions sentences about “the real essence of things,” “things in themselves,” and “the absolute.” In addition, Carnap rejects traditional philosophical ethics. He believes the usual utterances of ethical philosophers—such as “Killing is wrong”—mislead people by virtue of their grammatical form. They look like propositions, and so philosophers have given arguments to show that they are either true or false. Carnap, however, believes that what is grammatically an assertion, “Killing is wrong,” is logically not an assertion at all, but rather a disguised command, “Do not kill.” However, commands are neither true nor false and hence cannot be propositions. Ethics, then, is necessarily ruled out of the domain of philosophy.

Ethics and metaphysics are thus ruled out of philosophy proper. However, there must be something to them; otherwise why have people been so concerned about them? Here...

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Pragmatics, Semantics, and Syntax

(Student Guide to World Philosophy)

In other writings, Carnap has taken some pains to identify what he means by logical syntax. In the Foundations of Logic and Mathematics (1939), he has perhaps made the distinctions most clearly. In this work, he distinguishes pragmatics, semantics, and syntax as parts of the general philosophical concern with language that he calls “semiotic.” The first distinction that needs to be made here is between language that is about language and language that is not about language. One might, for example, assert the proposition: “The ball is red.” In this case, one would be using language to talk about the nonlinguistic world, to talk about a ball. However, one might then go on to talk about the proposition that refers to the red ball; one might say: “The proposition The ball is red’ has four words in it.” In this case, the proposition is not about objects (such as red balls) but about language itself. Such language about language is called “metalanguage”; language about objects is called “object language.” The general theory of an object language, stated in a metalanguage, is what Carnap means by “semiotic.” However, semiotics has three branches: pragmatics, semantics, and syntax. Pragmatics is an empirical study of three elements that can be distinguished in the use of a language—linguistic signs, the meanings (Carnap calls them “designata”) of the signs, and the users of the signs. Pragmatics studies all three elements....

(The entire section is 593 words.)

Formation and Transformation Rules

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In his second chapter, Carnap attempts to characterize and illustrate logical syntax somewhat more fully. He says syntax is a “formal” theory, meaning that syntax abstracts from all concerned with the sense or meaning of the signs and confines itself strictly to the forms of the signs or words. It consists entirely of rules specifying how signs—regarded simply as shapes or designs or sounds—may be combined and manipulated. Within this formal theory, there are formation and transformation rules. The formation rules, in effect, define what is to be regarded as a proper sentence. The ordinary person’s rejection of Russell’s well-known example of an ill-formed sentence—”Quadruplicity drinks procrastination”—is made by virtue of an appeal to the implicit formation rules of the English language. Ordinarily, of course, people abide by the implicit formation rules of English. Carnap’s formation rules are intended to make explicit these implicit rules that people follow. The other group of rules, the transformation rules, specify what manipulations can be performed on the well-formed sentences identified by the formation rules. The transformation rules are the rules of logical deduction expressed in syntactical terms. Carnap states that the two primitive terms in a logical syntax are “sentence” and “direct consequence.” That is to say, syntax attempts to identify what are proper sentences and also to specify how people are to draw their logical consequences.

There are other important syntactical terms in addition to “sentence” and “direct consequence,” however. Carnap spends a fair amount of time in the second chapter defining and illustrating these additional syntactical terms. He defines “valid” as the property a sentence has if it is a direct...

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Pseudo-object Sentences

(Student Guide to World Philosophy)

Just how Carnap feels he has avoided the morasses of traditional philosophy is best seen by looking at his discussion of what he calls “pseudo-object sentences.” Carnap feels that many times philosophers have combined syntactical predicates with nonsyntactical subjects. The result is neither one thing nor another; they are not statements in the object language nor are they statements in the metalanguage. They are, however, responsible for many of the disputes of traditional metaphysics about the reality or nonreality of entities such as universals. One example will perhaps illustrate Carnap’s distinction fairly clearly. He distinguishes three sentences:The rose is red. The rose is a thing. The word “rose” is a...

(The entire section is 649 words.)


(Student Guide to World Philosophy)

Additional Reading

Ayer, A. J., ed. Logical Positivism. Glencoe, Ill.: Free Press, 1959. This anthology of writings by logical positivists contains three papers by Rudolf Carnap, others by his associates, and a useful introduction by the editor, who favored the movement.

Cirera, Ramon. Carnap and the Vienna Circle. Amsterdam: Rodopi, 1994. A vigorous survey and interpretation of the philosophical views of Carnap and his colleagues in the Vienna Circle.

Coffa, J. Alberto. The Semantic Tradition from Kant to Carnap. Cambridge, England: Cambridge University Press, 1991. This study...

(The entire section is 486 words.)