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Philosophy And Logical Syntax
'My endeavour in these pages is to explain the main features of the method of philosophizing which we, the Vienna Circle, use, and by using try to develop further. It is the method of the logical analysis of science, or more precisely, of the syntactical analysis of scientific language.... The purpose of the book -- as of the lectures -- is to give a first impression of our method and of the direction of our questions and investigations to those who are not yet acquainted with them.' -- From the Preface.
- GenresPhilosophyNonfiction
100 pages, Paperback
First published January 1, 1935
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About the author
Rudolf Carnap
145 books107 followersRudolf Carnap, a German-born philosopher and naturalized U.S. citizen, was a leading exponent of logical positivism and was one of the major philosophers of the twentieth century. He made significant contributions to philosophy of science, philosophy of language, the theory of probability, inductive logic and modal logic. He rejected metaphysics as meaningless because metaphysical statements cannot be proved or disproved by experience. He asserted that many philosophical problems are indeed pseudo-problems, the outcome of a misuse of language.
Read more : http://www.iep.utm.edu/carnap/
Read more : http://www.iep.utm.edu/carnap/
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July 26, 2007
One of Carnap's perhaps unparalleled strengths amongst 20th century (and even among so-called Anglo-American-Quasi-German) philosophers is his commitment to fluid writing and clear, comprehensive presentations. Philosophy and Logical Syntax is one of this author's most readable works, and that would be saying a lot. While the work hardly touches the surface of what Carnap was up to, it presents the gist of what he was working on. Beginning with the "elimination of metaphysics" in highly condensed form, Carnap then proceeds to develop his argument that philosophy is logical analysis. He concludes with the extremely simplified but nevertheless important elements of his philosophy of science. While the work fails to do justice to Carnap's early works, it nevertheless presents an outline of what he was getting at to the reader new to Carnap.
December 24, 2024
A concise statement of the views of one of the great proponents of logical positivism from the Vienna Circle. Carnap claims here to speak for the Vienna circle as a whole. The method of philosophizing advocated for is intriguing. I will have to read more to see whether it is considered viable today.
I attempt a brief summary:
Chapter 1: The Rejection of Metaphysics
Carnap begins by distinguishing philosophy into Metaphysics, Psychology and Logic. We will be considering the mode of logical analysis in this book. One of the principle tasks of the logical analysis of a given proposition is to find out the method of verification for that proposition. There are two kinds of verification: direct and indirect. Direct verification is about a proposition that asserts something about a present perception. Indirect verification is something which is verified by direct verification of propositions deduced from P together with other already verified propositions. The proposition asserted here is a prediction which can be examined by observation. We may come to a degree of certainty sufficient for practical purposes, but we can never attain absolute certainty. Propositions are never subject to complete verification and hence they are called hypotheses. Natural laws are hypotheses. What gives theoretical meaning to a proposition is not the attendant images and thoughts but the possibility of deducing from it perceptive propositions, in other words, the possibility of verification.
The author will call metaphysical all those propositions which claim to represent knowledge about something which is beyond experience. These propositions are not verifiable. Therefore, it has no sense. Doubtless, metaphysicians may have images connected to these propositions but they cannot give sense to this proposition. This analysis also applies to epistemological doctrines like realism, idealism, solipsism etc. We can have verification about particular elements or parts of a system but not the world as a whole, which is the question these epistemologists raise. These assertions have no empirical content and therefore no sense at all. Carnap neither asserts nor denies these theses, but rejects the whole question. These are pseudo-theses since we are not able to make any further prediction as to future experiences.
As to normative ethics, philosophers have been deluded into thinking that a value statement is an assertive proposition and must be either true or false. But a value statement is nothing else than a command in a misleading grammatical form. It does not assert anything and can neither be proved nor disproved. Psychological ethics is part of empirical science e.g. deciding whether the feeling of remorse accompanies the act of murder. The propositions of ethics are part of metaphysics as Carnap defines the term. These propositions certainly have an effect, they express something. Carnap distinguishes between the expressive and the assertive function of language. Metaphysics is part of the expressive function of language and thus analogous to poetry. They are neither true nor false because they assert nothing. They have no theoretical content.
The next step in his argument will be to eliminate psychology from the field of philosophy, such that we are left with logic alone. Psychological propositions certainly have sense. From such propositions we can deduce other propositions about future experiences. But the propositions of psychology belong to the region of empirical science, not philosophy. The only proper task of philosophy is logical analysis. Now, we have to determine the character of logical analysis. Carnap agrees with Hume's view that the propositions of mathematics and empirical science have sense and all other propositions are without sense. What about the philosophical propositions he himself raises? Wittgenstein's answer here was that they too were without sense, one should throw away the ladder after one has climbed through them. Carnap disagrees. For him, propositions of logical analysis do indeed have sense as will be shown in the next few chapters.
Chapter Two: Logical Syntax of Language
The logical syntax of a language is to be understood as the formal theory of that language. A formal investigation of a certain sentence does not concern the meaning of the sentence but only the syntax. In mathematics, this is akin to Hilbert's metamathematics. The formation rules of a certain language-system S determines how sentences of the system S can be constructed out of the different kinds of symbols. But note an important difference between logical syntax and grammatical syntax. The rules of grammatical syntax are not always formal -- for example, in Latin certain substantives have gender. For natural languages, the rules of syntax can hardly be given -- they are too complicated. For logical languages, it is easier to do so as Russell and Whitehead did in the Principia Mathematica. The Transformation rules are rules that determine how given sentences may be transformed into others; how from given sentences we may infer others. The totality of the transformation-rules of a language system S may be formulated as the definition of the term 'direct consequence in S'. A language system is a system of rules of formation and transformation. Modern logic has shown that the rules of inference can be expressed in a purely formal manner. There is no fundamental difference between logic and grammar, between transformation rules and formation rules. Thus, Carnap applies the term syntax to both. Additionally, note we will be using the term sentence and not the word proposition. This is because sometimes 'proposition' refers not to a sentence, but to what is expressed by a sentence. Sentences will be considered not as to do with mental acts or meanings but as series of symbols.
The terms 'sentence' and 'direct consequence' are the two primitive terms of logical syntax. We cannot define the values of true or false in logical syntax, since that will depend upon experience. However, a sentence may be true or false only be reasons of the rules of the language. We will call this VALID and CONTRA-VALID respectively. We will call a sentence DETERMINATE if it is either valid or contravalid. The determinate sentences are those whose truth-value is determined by the rules of the language. We will call a sentence INDETERMINATE if it is neither valid nor contravalid. For example, aSb is an indeterminate sentence. Transformation rules of the logical or mathematical character, such as in the Principia, we will call L-RULES. Newton's laws or Maxwell's equations will be physical rules or P-RULES. A transformation rule of a language is either an L-rule or a P-rule. We will call a sentence C a CONSEQUENCE of a class P of sentences -- the premises -- if there is a chain of sentences constructed according to the transformation rules connecting the class P with the sentence C. We will call a sentence which is true by reason of the L-rules alone -- L-VALID or ANALYTIC. We will call a sentence which is false by reason of the L-rules alone, L-CONTRAVALID or CONTRADICTORY. A sentence is called L-DETERMINATE if it is either analytic or contradictory. If the L-rules do not suffice, then we may call it L-INDETERMINATE or SYNTHETIC. If a sentence is valid, but not analytic, we call it P-VALID. If a sentence is contra-valid but not contradictory we call it P-CONTRAVALID. We may simplify this into three kinds of sentences: analytic, synthetic, and contradictory.
The class of the non-valid consequences of a given sentence is called the CONTENT of this sentence. The content of a sentence represents its sense, so far as the word sense is intended to designate something of a purely logical, not a psychological character. Sometimes, two sentences of quite unlike wording may nevertheless have the same sense as asserting the same state. We will call such sentences EQUIPOLLENT. Two expressions which are not themselves sentences occuring in sentences may have the same sense, the same meaning despite different wordings -- we will call this SYNONYMOUS.
Now, we have to distinguish three kinds of sentences. SYNTACTICAL sentences concern the form of linguistic expressions e.g. 2+2=4. Those sentences which concern not linguistic expressions but extra-linguistic objects may be called REAL OBJECT-SENTENCES. The third kind is PSEUDO OBJECT-SENTENCES. These are amphibious in that they have the form of object-sentences but are like syntactical sentences with regard to their contents. Real object-sentences belong to empirical science e.g. The Rose is red (this is synthetic). Pseudo-object sentences belong to the material mode of speech (to be dealt with later) e.g. The Rose is a thing (this is analytic). Syntactical sentences are part of the formal mode of speech e.g. The word 'rose' is a thing-word. Note that the last two sentences assert the same. We may call the quality of being a thing-designation a PARALLEL SYNTACTICAL QUALITY to the quality of being a thing. Carnap gives some examples here to show that the material mode of speech is pseudo-object sentences and can be translated into the formal mode of speech or syntactical sentences. Pseudo object-sentences only asserts something aobout two designations, not about the objects themselves.
Chapter Three: Syntax as the Method of Philosophy
Many sentences, especially philosophical ones, which are really syntactical, deceive us because we mistake them for object-sentences. Now let us turn to a discussion of modality -- possibility, impossibility, necessity, contingency. Modality sentences are in fact veiled syntactical sentences, that is sentences of the material mode of speech. Thus, (for logical and physical, respectively) impossibility is contradictory or contravalid, possibility is non-contradictory or non-contravalid. Necessary is analytic or valid. Contingency is synthetic or indeterminate. The material mode of speech often gets us into useless philosophical controversies. The relativity of all philosophical these s in regard to language, that is, the need of reference to one or several particular language-systems is a very essential point to keep in mind. It is on account of the general use of the material mode of speech that this relativity is unnoticed. Questions in the material mode of speech are metaphysical pseudo-questions. It is sometimes difficult to translate philosophical questions into formal mode. Since they are not translatable as such, they are pseudo-questions. Epistemology too is a part of syntax, as the logical analysis of verification is the syntactical analysis of those transformation rules which determine the deduction of observation sentences.
Most metaphysics is basically poetry. All questions about the structure of space and time, for example, are syntactical questions, that is questions about the structure of language and especially the structure of the formation and transformation rules concerning space and time coordinates. The objection may be raised now: is not the form of physical laws dependent upon the experimental results of physical investigations and not a merely theoretical consideration? This is true, but bear in mind the fact that the empirical results do not dictate their choice between the deterministic and the statistical form of the laws. The form in which a law has to be stated is to be decided by an act of volition. However close the connection between the empirical results and the form of physical laws may be, the question concerning the form of these laws is in every case a syntactical question. Both points of view, the empirical view of physics and the formal one of syntax need to be taken into consideration for all questions of natural philosophy.
Carnap says that at the Vienna Circle, they have arrived at the conclusion that the physical language in which physical things are discussed is the basic language of all science. Otto Neurath in particular is to credit for this. Carnap espouses here a behaviorist psychology. He notes an objection: that there is conceivable a psychological quality which never has any effect upon behaviour. He replies thus: Firstly: if there is in the psychological language a predicate which is originally used in describing one's own mental state, experienced by introspection, then the mere using of this predicate in speaking or writing is an expression of this state. Secondly, linguistic expressions of the state designated by the predicate exist which can be used by other speakers. This is the reply Carnap makes to this objection. Physicalism, in Carnap's sense, asserts that for every psychological sentence S1, there is a corresponding physical sentence S2, so that S1 and S2 are equipollent on account of certain valid laws. Physicalism does not assert something akin to the identity theory of mind which would be part of the material mode of speech. This would be metaphysics and thus senseless.
In close connection with physicalism is the thesis of the unity of science. If every sentence can be translated into the physical language, then this language is an all-embracing language, a universal language of science. Physical sciences, psychology, social sciences constitute one uniform science. Actually, this would be speaking in the material mode of speech. Let us indeed reformulate this in the formal mode of speech: the terms of all branches of science are logically uniform. Carnap concludes that the analysis of the formal structure of language as a system of rules is the only method of philosophy.
I attempt a brief summary:
Chapter 1: The Rejection of Metaphysics
Carnap begins by distinguishing philosophy into Metaphysics, Psychology and Logic. We will be considering the mode of logical analysis in this book. One of the principle tasks of the logical analysis of a given proposition is to find out the method of verification for that proposition. There are two kinds of verification: direct and indirect. Direct verification is about a proposition that asserts something about a present perception. Indirect verification is something which is verified by direct verification of propositions deduced from P together with other already verified propositions. The proposition asserted here is a prediction which can be examined by observation. We may come to a degree of certainty sufficient for practical purposes, but we can never attain absolute certainty. Propositions are never subject to complete verification and hence they are called hypotheses. Natural laws are hypotheses. What gives theoretical meaning to a proposition is not the attendant images and thoughts but the possibility of deducing from it perceptive propositions, in other words, the possibility of verification.
The author will call metaphysical all those propositions which claim to represent knowledge about something which is beyond experience. These propositions are not verifiable. Therefore, it has no sense. Doubtless, metaphysicians may have images connected to these propositions but they cannot give sense to this proposition. This analysis also applies to epistemological doctrines like realism, idealism, solipsism etc. We can have verification about particular elements or parts of a system but not the world as a whole, which is the question these epistemologists raise. These assertions have no empirical content and therefore no sense at all. Carnap neither asserts nor denies these theses, but rejects the whole question. These are pseudo-theses since we are not able to make any further prediction as to future experiences.
As to normative ethics, philosophers have been deluded into thinking that a value statement is an assertive proposition and must be either true or false. But a value statement is nothing else than a command in a misleading grammatical form. It does not assert anything and can neither be proved nor disproved. Psychological ethics is part of empirical science e.g. deciding whether the feeling of remorse accompanies the act of murder. The propositions of ethics are part of metaphysics as Carnap defines the term. These propositions certainly have an effect, they express something. Carnap distinguishes between the expressive and the assertive function of language. Metaphysics is part of the expressive function of language and thus analogous to poetry. They are neither true nor false because they assert nothing. They have no theoretical content.
The next step in his argument will be to eliminate psychology from the field of philosophy, such that we are left with logic alone. Psychological propositions certainly have sense. From such propositions we can deduce other propositions about future experiences. But the propositions of psychology belong to the region of empirical science, not philosophy. The only proper task of philosophy is logical analysis. Now, we have to determine the character of logical analysis. Carnap agrees with Hume's view that the propositions of mathematics and empirical science have sense and all other propositions are without sense. What about the philosophical propositions he himself raises? Wittgenstein's answer here was that they too were without sense, one should throw away the ladder after one has climbed through them. Carnap disagrees. For him, propositions of logical analysis do indeed have sense as will be shown in the next few chapters.
Chapter Two: Logical Syntax of Language
The logical syntax of a language is to be understood as the formal theory of that language. A formal investigation of a certain sentence does not concern the meaning of the sentence but only the syntax. In mathematics, this is akin to Hilbert's metamathematics. The formation rules of a certain language-system S determines how sentences of the system S can be constructed out of the different kinds of symbols. But note an important difference between logical syntax and grammatical syntax. The rules of grammatical syntax are not always formal -- for example, in Latin certain substantives have gender. For natural languages, the rules of syntax can hardly be given -- they are too complicated. For logical languages, it is easier to do so as Russell and Whitehead did in the Principia Mathematica. The Transformation rules are rules that determine how given sentences may be transformed into others; how from given sentences we may infer others. The totality of the transformation-rules of a language system S may be formulated as the definition of the term 'direct consequence in S'. A language system is a system of rules of formation and transformation. Modern logic has shown that the rules of inference can be expressed in a purely formal manner. There is no fundamental difference between logic and grammar, between transformation rules and formation rules. Thus, Carnap applies the term syntax to both. Additionally, note we will be using the term sentence and not the word proposition. This is because sometimes 'proposition' refers not to a sentence, but to what is expressed by a sentence. Sentences will be considered not as to do with mental acts or meanings but as series of symbols.
The terms 'sentence' and 'direct consequence' are the two primitive terms of logical syntax. We cannot define the values of true or false in logical syntax, since that will depend upon experience. However, a sentence may be true or false only be reasons of the rules of the language. We will call this VALID and CONTRA-VALID respectively. We will call a sentence DETERMINATE if it is either valid or contravalid. The determinate sentences are those whose truth-value is determined by the rules of the language. We will call a sentence INDETERMINATE if it is neither valid nor contravalid. For example, aSb is an indeterminate sentence. Transformation rules of the logical or mathematical character, such as in the Principia, we will call L-RULES. Newton's laws or Maxwell's equations will be physical rules or P-RULES. A transformation rule of a language is either an L-rule or a P-rule. We will call a sentence C a CONSEQUENCE of a class P of sentences -- the premises -- if there is a chain of sentences constructed according to the transformation rules connecting the class P with the sentence C. We will call a sentence which is true by reason of the L-rules alone -- L-VALID or ANALYTIC. We will call a sentence which is false by reason of the L-rules alone, L-CONTRAVALID or CONTRADICTORY. A sentence is called L-DETERMINATE if it is either analytic or contradictory. If the L-rules do not suffice, then we may call it L-INDETERMINATE or SYNTHETIC. If a sentence is valid, but not analytic, we call it P-VALID. If a sentence is contra-valid but not contradictory we call it P-CONTRAVALID. We may simplify this into three kinds of sentences: analytic, synthetic, and contradictory.
The class of the non-valid consequences of a given sentence is called the CONTENT of this sentence. The content of a sentence represents its sense, so far as the word sense is intended to designate something of a purely logical, not a psychological character. Sometimes, two sentences of quite unlike wording may nevertheless have the same sense as asserting the same state. We will call such sentences EQUIPOLLENT. Two expressions which are not themselves sentences occuring in sentences may have the same sense, the same meaning despite different wordings -- we will call this SYNONYMOUS.
Now, we have to distinguish three kinds of sentences. SYNTACTICAL sentences concern the form of linguistic expressions e.g. 2+2=4. Those sentences which concern not linguistic expressions but extra-linguistic objects may be called REAL OBJECT-SENTENCES. The third kind is PSEUDO OBJECT-SENTENCES. These are amphibious in that they have the form of object-sentences but are like syntactical sentences with regard to their contents. Real object-sentences belong to empirical science e.g. The Rose is red (this is synthetic). Pseudo-object sentences belong to the material mode of speech (to be dealt with later) e.g. The Rose is a thing (this is analytic). Syntactical sentences are part of the formal mode of speech e.g. The word 'rose' is a thing-word. Note that the last two sentences assert the same. We may call the quality of being a thing-designation a PARALLEL SYNTACTICAL QUALITY to the quality of being a thing. Carnap gives some examples here to show that the material mode of speech is pseudo-object sentences and can be translated into the formal mode of speech or syntactical sentences. Pseudo object-sentences only asserts something aobout two designations, not about the objects themselves.
Chapter Three: Syntax as the Method of Philosophy
Many sentences, especially philosophical ones, which are really syntactical, deceive us because we mistake them for object-sentences. Now let us turn to a discussion of modality -- possibility, impossibility, necessity, contingency. Modality sentences are in fact veiled syntactical sentences, that is sentences of the material mode of speech. Thus, (for logical and physical, respectively) impossibility is contradictory or contravalid, possibility is non-contradictory or non-contravalid. Necessary is analytic or valid. Contingency is synthetic or indeterminate. The material mode of speech often gets us into useless philosophical controversies. The relativity of all philosophical these s in regard to language, that is, the need of reference to one or several particular language-systems is a very essential point to keep in mind. It is on account of the general use of the material mode of speech that this relativity is unnoticed. Questions in the material mode of speech are metaphysical pseudo-questions. It is sometimes difficult to translate philosophical questions into formal mode. Since they are not translatable as such, they are pseudo-questions. Epistemology too is a part of syntax, as the logical analysis of verification is the syntactical analysis of those transformation rules which determine the deduction of observation sentences.
Most metaphysics is basically poetry. All questions about the structure of space and time, for example, are syntactical questions, that is questions about the structure of language and especially the structure of the formation and transformation rules concerning space and time coordinates. The objection may be raised now: is not the form of physical laws dependent upon the experimental results of physical investigations and not a merely theoretical consideration? This is true, but bear in mind the fact that the empirical results do not dictate their choice between the deterministic and the statistical form of the laws. The form in which a law has to be stated is to be decided by an act of volition. However close the connection between the empirical results and the form of physical laws may be, the question concerning the form of these laws is in every case a syntactical question. Both points of view, the empirical view of physics and the formal one of syntax need to be taken into consideration for all questions of natural philosophy.
Carnap says that at the Vienna Circle, they have arrived at the conclusion that the physical language in which physical things are discussed is the basic language of all science. Otto Neurath in particular is to credit for this. Carnap espouses here a behaviorist psychology. He notes an objection: that there is conceivable a psychological quality which never has any effect upon behaviour. He replies thus: Firstly: if there is in the psychological language a predicate which is originally used in describing one's own mental state, experienced by introspection, then the mere using of this predicate in speaking or writing is an expression of this state. Secondly, linguistic expressions of the state designated by the predicate exist which can be used by other speakers. This is the reply Carnap makes to this objection. Physicalism, in Carnap's sense, asserts that for every psychological sentence S1, there is a corresponding physical sentence S2, so that S1 and S2 are equipollent on account of certain valid laws. Physicalism does not assert something akin to the identity theory of mind which would be part of the material mode of speech. This would be metaphysics and thus senseless.
In close connection with physicalism is the thesis of the unity of science. If every sentence can be translated into the physical language, then this language is an all-embracing language, a universal language of science. Physical sciences, psychology, social sciences constitute one uniform science. Actually, this would be speaking in the material mode of speech. Let us indeed reformulate this in the formal mode of speech: the terms of all branches of science are logically uniform. Carnap concludes that the analysis of the formal structure of language as a system of rules is the only method of philosophy.
January 31, 2024
This very short work (it was originally 100 small pages, I read a version that was 34 8 1/2 x 11 manuscript pages) is Carnap's attempt to summarize and present the position of the Vienna Circle, logical positivism, to a general audience. It was based on a series of lectures Carnap gave at the University of London in 1934. Here Carnap details that only empirical (scientific), mathematical and logical statements have any sense with all other statements of normative ethics and abstract metaphysics consigned to the expressive function of language along with poetry. Also explicated was Carnap's project more fully explored in the Logical Syntax of Language (Logische Syntax der Sprache) of showing how a language system could be delineated in terms of physical and logical rules in order to allow analysis of propositions into logical-mathematical, physical and metaphysical (expressive) to properly assign work and dissolve disputes.
This book has virtues of being short and emphatic. I suspect that some who will say "the logical positivists never said that" will be chagrinned to learn Carnap said that in this book. Carnap proports to speak for the Vienna Circle in this book, but my sense is that would be open to challenge. The effect is interesting, but at least to me not convincing. For example, I think ultimately there is a tension between the extent to which what Carnap calls choice of language (choice of theoretical-system or world-view perspective) determines answers to substantive questions and the rejection of non-empirical claims because of their capriciousness in relating to empirical claims.
As mentioned I read this book in the form of the document produced by the Carnap Project, labeled Carnap Project: Benson No. 1935–1. The pdf is fine, the original book (which I also read some time ago from a library in 1935 edition) is probably easier to read, but versions like this make it readily available for those interested.
This book has virtues of being short and emphatic. I suspect that some who will say "the logical positivists never said that" will be chagrinned to learn Carnap said that in this book. Carnap proports to speak for the Vienna Circle in this book, but my sense is that would be open to challenge. The effect is interesting, but at least to me not convincing. For example, I think ultimately there is a tension between the extent to which what Carnap calls choice of language (choice of theoretical-system or world-view perspective) determines answers to substantive questions and the rejection of non-empirical claims because of their capriciousness in relating to empirical claims.
As mentioned I read this book in the form of the document produced by the Carnap Project, labeled Carnap Project: Benson No. 1935–1. The pdf is fine, the original book (which I also read some time ago from a library in 1935 edition) is probably easier to read, but versions like this make it readily available for those interested.
February 16, 2023
7/10 - Viewed from a modern perspective. This is maybe unnecessarily harsh when considered in the context it was written.
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