What is metaphysics? In this regard, Carnap's answer is: I will call all those propositions metaphysical, that is, these propositions claim to express knowledge of things that are higher than or beyond all experience, for example, knowledge about the true nature of things, knowledge about things themselves and absoluteness. Eier also defined metaphysics as the exploration of the essence of reality. He pointed out that metaphysics is mainly based on the basic assumption that philosophy can provide us with knowledge about reality beyond the scientific world and common sense. It can be seen that in the view of logical positivism, all propositions about the origin and essence of the world and all knowledge about transcendental reality are metaphysics.
Logical positivism rejects metaphysics because metaphysical propositions cut off the connection with the empirical world, which is meaningless in experience and theory, that is, in understanding. The so-called metaphysical proposition has no empirical significance, which means that the objects involved in this kind of proposition are not within the scope of sensory experience, and can neither be confirmed nor denied by experience. In other words, a metaphysical proposition can't be sure whether it is true or false within the scope of experience, and a proposition without true or false value can't provide us with any knowledge because it has no conclusive content, which is of no help to enhance our understanding. In logical positivism, people always understand the meaning of words from the perspective of cognitive meaning. Accordingly, metaphysical propositions are meaningless pseudo-propositions. Carnap said that we neither affirm nor deny these topics, but we reject the whole question.
So, what proposition is meaningful? All propositions with true and false values are meaningful. There are two kinds of meaningful propositions, namely, analytical propositions and comprehensive propositions. The truth value of an analytical proposition can be inferred by means of logical rules, because the meaning of the predicate in the analytical proposition is contained in the subject; The truth of comprehensive propositions can be tested by experience, because comprehensive propositions state empirical facts. If a proposition is neither true nor false, then it is cognitively meaningless. Metaphysical propositions can neither be judged according to logical rules nor according to empirical facts. It is neither true nor false, but a false proposition with no true or false value and no meaning. Therefore, Eier said that metaphysical propositions have no meaning, not only from the fact that they have no factual content. There is no factual content to infer from the fact that they are not innate propositions. Carnap also said: Metaphysical propositions are meaningless because they don't involve any facts. Hume has expressed this view. We agree with Hume's view that it is meaningful to translate into our terms the propositions of mathematics and empirical science, and all other propositions are meaningless. The difference between analytical proposition and comprehensive proposition and the view that these two kinds of propositions are meaningful are the theoretical basis for logical positivism to reject metaphysics.
Since metaphysics is meaningless, why do so many people, including outstanding people of insight, spend so much energy and enthusiasm on metaphysics throughout the ages? In this regard, Carnap pointed out that although the metaphysical proposition has no meaning in understanding, it does not mean that it has no value, nor does it exclude that it has emotional significance. Because metaphysics does express something, which, like laughter, lyric poetry and music, expresses people's eternal feelings or will and expresses a person's general attitude towards life. In this case, why does logical positivism not exclude lyric poetry but only metaphysics? In this regard, Carnap's point of view is that although metaphysics and lyric poetry have great similarities, there are also decisive differences, that is, lyric poetry is a literary work, and no one will look for scientific knowledge in lyric poetry. But metaphysical scholars believe that he has provided people with some knowledge of truth. In this respect, metaphysical scholars not only deceive others, but also deceive themselves. Carnap pointed out that the non-theoretical nature of metaphysics itself is not a defect, and all arts have this non-theoretical nature without losing their high value to personal and social life. The problem is that metaphysics has the nature of deceiving and confusing people, that is, it gives people the illusion of knowledge, but in fact it does not give people any knowledge. Carnap said: That's why we should reject it. Logical positivism holds that since ancient times, people have not understood the essence of metaphysical propositions, and have been arguing blindly and endlessly for thousands of years without results. Logical positivism clarified the essence of metaphysical proposition for the first time, and solved this debate once and for all.
So how does logical positivism exclude metaphysics? On this issue, Carnap's article "Eliminating Metaphysics through Logical Analysis of Language" is quite representative.
Carnap's argument is that logical analysis reveals that metaphysical assertion statements are false statements. He pointed out that language includes vocabulary and syntax. Therefore, there are two kinds of false statements: one is that it contains a word that is mistaken for meaningful; The other is that although the words that make up a sentence are meaningful, they are put together in a way that violates syntax, so they do not constitute a meaningful statement.
Let's look at the first wrong statement, that is, a sentence contains a word that is mistakenly thought to be meaningful, but in fact the word is meaningless and just a wrong concept. So, what is the meaning of a word? Carnap pointed out that what determines the meaning of a word is its application standard (that is, the deducible relationship formed by its basic sentence patterns, truth conditions and verification methods). Applying standards is a sufficient condition for determining meaning. In the final analysis, the meaning of a word lies in whether it can be confirmed by experience. For example, X is a diamond. In this sentence, X is used to refer to diamonds, which belong to the category of things and can be tested by experience, so it is meaningful. Many metaphysical words can't meet the above conditions, so they are meaningless. For example, x is the origin of the world. Here x is used to refer to primitive, and the word primitive is a meaningless word. Because the so-called origin of metaphysics, that is, from the past, does not mean that time comes first, but that metaphysics comes first. Because there is no standard in this metaphysical aspect, the word primitive man is a meaningless false concept, and the sentence containing this false concept is a metaphysical false statement.
Look at the second false statement. In this statement, although the words that make up the sentence are meaningful and put together in a way that violates syntax, they are meaningless. Carnap pointed out: The syntax of a language stipulates which combinations of words are allowed and which are not. However, the grammar and syntax of natural language cannot completely eliminate all meaningless word combination tasks. For example, Caesar is a prime number, which conforms to the rules of natural grammar, but it is obviously a meaningless false statement, because names and numbers belong to different logical types. Carnap pointed out that this fact shows that from a logical point of view, grammar and syntax are inappropriate. If grammar and syntax accurately conform to logical syntax, there will be no false statements. Of course, many metaphysical false statements are not as obvious as the above example. Taking Descartes' "I think, therefore I am" as an example, Carnap pointed out that this proposition contains two basic logical errors: the first error is that I am in this conclusion. Because existence is not an attribute, it can only be used with predicates, not with names (subject proper nouns), and it cannot be said that I exist, "God" exists, and mysterious forces exist. The second mistake lies in the transition from my thinking to my existence. Because, I think the conclusion is not that I am, but that there is something worth thinking about. Through the above analysis, Carnap draws the following conclusion: A meaningful metaphysical statement is impossible.
Rejecting metaphysics is the programmatic slogan of logical positivism, and it is also the basic starting point and one of the main purposes of logical positivism. Because only by rejecting metaphysics can philosophy be transformed from a traditional knowledge system into an activity of logical analysis, and meaningful concepts and propositions can be clarified through logical analysis, laying a logical foundation for factual science and mathematics. The so-called meaning standard refers to the standard to judge whether a proposition has cognitive meaning, that is, to judge whether a proposition is true or false. As Carnap said, knowing a sentence means knowing when it is possible to be true and when it is possible to be false. A proposition that is likely to be true or false is meaningful, and vice versa is meaningless. Because a proposition without true or false value and conclusive content can't provide us with any knowledge. In logical positivism, the standard of meaning is the theoretical basis for rejecting metaphysics and the standard for distinguishing science from metaphysics.
As mentioned above, logical positivism divides meaningful propositions into two categories: analytical propositions or mathematical logic propositions, comprehensive propositions or empirical scientific propositions. In their view, analytical propositions include two types: tautology and contradiction. It is always true that tautology is repeated in the same language, for example, all widowers are male; Contradictions are always false, such as some widowers who are not men. Because the truth value of an analytical proposition can be inferred by logical rules, that is, its truth value can be determined from logical relations, so the analytical proposition has logical or formal significance. Comprehensive proposition is a proposition of empirical science. Because this kind of proposition is based on empirical facts, its truth can be confirmed by experience, so it has empirical significance. Logical positivism refers to the criteria for judging whether a comprehensive proposition, that is, an empirical scientific proposition, is meaningful, which is called empirical salience or empirical salience criteria.
So, how to determine the significance of an empirical scientific proposition? In this regard, logical positivism puts forward a famous principle, that is, the principle of confirmability or the principle of empirical confirmation. The so-called confirmatory principle refers to whether a proposition is meaningful or not and whether it is an empirical scientific proposition depends on whether there is a way to prove it by experience. A proposition that can be proved or falsified is meaningful, and vice versa is meaningless. Accordingly, the significance of a proposition lies in the method of proving it. Shrek pointed out that stating the meaning of a sentence is equivalent to stating the rules of using the sentence, which is also the way to state the affirmation (or negation) of the sentence. The meaning of a proposition is the way to prove it. The principle of confirmation is to determine whether a proposition is meaningful or not and whether it is the standard of empirical scientific proposition. In other words, the criterion of empiricism is the principle of corroboration. These two problems are actually closely linked. As Carnap said, the two main problems of epistemology are meaning and confirmation &; & lt33; & amp& lt33; In a sense, there is only one answer to these two questions. If we know what makes a statement be found to be true, then we also know its meaning &; & lt33; & amp& lt33; Therefore, the meaning of a statement is in a sense equivalent to the way we decide whether it is true or not; Only when such a decision is possible can the statement make sense.
In addition, the principle of confirmation only requires that it can be proved in principle, that is, a sentence is meaningful if and only if it can be proved (or disproved) in principle. The so-called verifiability in principle means the logical possibility of verification, not the possibility of practice. Shrek said: It must be emphasized that when we talk about verifiability, we mean the logical possibility of verification, and nothing else. Eier also pointed out that there are some meaningful propositions about facts that we can't confirm even if we want to, just because the conditions are temporarily unavailable. However, we can theoretically assume that once the conditions are met, it can be confirmed. So I think that if that proposition is unverifiable in practice and verifiable in principle, then that proposition is meaningful. Note that in logical positivism, the principle of confirmation is only the standard of meaning, not the standard of truth. It is not a method to judge whether a proposition is actually true or false, but a possible method to judge whether a proposition is true or false. As the standard of meaning, the principle of confirmation is a necessary condition for exploring truth, that is, the meaning of a proposition must be determined or clarified before it can be judged whether it is truth or not.
The significance standard of empiricism is the principle of corroboration. According to this principle, Schlick pointed out that the meaning of a proposition is the method to prove it. Carnap also said: One of the main tasks of logical analysis of a given proposition is to find a way to prove that proposition. Since the significance of the proposition lies in the way of proof, what is the way of proving the proposition? In other words, what methods are used to prove or deny a proposition? On this issue, logical positivism has put forward many different schemes.
Carnap pointed out that we must distinguish between two kinds of confirmation, that is, true confirmation and indirect confirmation. The so-called direct confirmation is to compare the proposition to be confirmed with our current experience. Any proposition that concludes current perception (such as that this flower is red) can be directly tested by our current perception. The so-called indirect confirmation means that a proposition P that cannot be directly confirmed can only be confirmed by truly confirming those propositions derived from P and other confirmed propositions. It can be seen that the so-called indirect confirmation ultimately boils down to or reverts to direct confirmation, but there is only one more logical deduction process. In Carnap's view, all propositions of empirical science can be confirmed (or falsified) by direct or indirect methods.
In addition to the above methods, some logical positivists also propose to determine the meaning of a proposition by logical deduction, that is, whether a proposition is meaningful depends on whether an observable proposition can be logically deduced from it.
For example, the verifiability standard put forward by weismann states that if any proposition S is meaningful in knowledge, there must be an observation proposition O&; & lt33; & amp& lt33; The finite set of O makes S deduce O &；; & lt33; & amp& lt33; O, and s is derived from the latter. For example, to make sure that the proposition (all swans are white) is meaningful, we must be able to deduce a series of observation propositions O from S (this is a swan and white), and vice versa, we can also deduce proposition S from these observation propositions O. The expression of weismann's verifiability standard is obviously too harsh, and many propositions in scientific theory cannot be realized. So Eier put forward a more moderate expression of verifiability standard, that is, any proposition S must have an observation proposition O&; & lt33; & amp& lt33; The finite set of O leads S to derive o &；; & lt33; & amp& lt33; O conjunctive formula, and o &；; & lt33; & amp& lt33; O confirm s or give s a definite probability. This expression only requires that the observation proposition be derived from S, but not from the observation proposition. As long as the observation proposition can confirm S, that is, give S a certain probability and make S possible, then the proposition S is meaningful. In other words, Eier's statement does not require proposition S to be completely confirmed. Logical positivism holds that scientific theory is relative and can never be completely proved, otherwise science cannot develop.
Eier's expression is obviously much looser than weismann's, so it is called weak verifiable standard, while weismann's expression is called strong verifiable standard. Eier explains the difference between the strong meaning and the weak meaning of the word verifiable as follows: a proposition is considered verifiable if and only if its truth can be verified by experience. If experience can make it possible, it is provable in a weak sense.
As a standard of meaning, the principle of empirical confirmation is a core theory of logical positivism and a methodological principle used by them to reject metaphysics and lay the foundation of scientific knowledge. However, due to many insurmountable theoretical difficulties and criticisms from all sides, the confirmation principle has been continuously relaxed. It can be said that the disagreement and debate on the principle of confirmation of logical positivism is an important factor leading to the differentiation and evolution of this school. According to the meaning standard of empiricism, the way to judge whether a proposition is meaningful is to compare it with empirical facts. Newrat, Carnap and others soon found that there were two problems in this method: first, in theory, scientific propositions could not be completely confirmed; Secondly, comparing propositions with empirical facts, there are still metaphysical relics of solipsism. So Carnap and others put aside the empirical content of propositions and turned to study the logical syntax of language.
The so-called logical syntax of language refers to the theory of language form. The study of language form only involves the form of language, but not its content, that is, it mainly studies the rules, definitions, sentences and the types and arrangements of symbols in language, but not the meaning of these symbols or sentences. Carnap pointed out that formal language should be understood as a system of speaking rules. The rule system of formal language includes formation rules and deformation rules. Word formation rules are similar to grammar, and a systematic word formation rule determines how the sentences of the system are composed of various symbols. For example, the subject symbol S can be connected with the predicate symbol P with a copula to form a sentence with S as P. The transformation rules are similar to deductive logic, which stipulates how to transform a given sentence into other sentences, that is, how to deduce other sentences from some given sentences. For example, it can be inferred from all S's being P's, or all A's being B's and all B's being C's. Carnap believes that word formation rules and deformation rules are two basic rules that constitute a language system, and the logical syntax of a language system is composed of these two parts. Since the rules of logical syntax have nothing to do with the specific meaning of sentences, they are expressed in a purely formal way, we can determine which sentence forms are allowed or meaningful by the language system and which sentence forms are not allowed or meaningless by determining the formation rules and deformation rules of a language system.
As for how to determine the rule system of language form, Carnap advocates the principle of tolerance or convention of language form. According to this principle, any language system has the right to exist as long as it has logical consistency and self-sufficiency. People can choose any language system at will, because there is no right or wrong in different language systems, only the question of convenience and suitability for a certain purpose.
Carnap thinks that logical syntax of language is a theory about language form. Therefore, the study of logical syntax of language is to analyze the formal structure of language as a rule system. To analyze a language system logically and syntactically, we must first distinguish two different ways of speaking, namely, formal way of speaking or substantive way of speaking. Formal speech only involves the expression of language, that is, the syntactic form between words, but not the object of language expression. Formal speech adopts syntactic sentences, for example, the word rose is a material word. The substantive way of speaking seems to involve the object from the form of expression, but strictly speaking, it only involves the name of the object. Therefore, the sentences used in the substantive way of speaking, which seem to be true object sentences, are actually false object sentences. For example, a rose is a thing, and this sentence and the real-object sentence, such as a rose is red, seem to involve the object of a rose in terms of expression, but in fact a rose is something that only involves the name of a rose, but not any of its attributes, such as color, shape, smell and so on. The real way of speaking is to speak with false object sentences.
Carnap pointed out that using false object sentences or substantive ways of speaking often leads to misunderstanding, confusion and unnecessary arguments, especially in the field of philosophy. Many unnecessary arguments in traditional philosophy are caused by the use of substantive ways of speaking. For example, positivists claim that things are a combination of sensory materials, while realists claim that things are a combination of physical elements, so there will be endless arguments about the false question of what things are. The solution to this argument is to translate the substantive way of speaking into the formal way of speaking. Formal language habits are expressed as follows: the name of a physical object (such as the word moon) can be simplified as a sensory data predicate (or perceptual predicate). Carnap thinks that if we change the substantive way of speaking into the formal way of speaking, it is possible to reconcile these two opposing propositions and eliminate the argument about metaphysical fallacies.
This method of using formal speech mode instead of substantive speech mode and syntactic sentence instead of false object sentence is the analysis method of logical syntax. Its specific methods are: replacing things with things, replacing relationships with relationships, replacing numbers with numbers, replacing time with time, and so on. Carnap believes that by translating this way of speaking into form, we can get rid of all the hints of objects outside the language, so we only care about the form of language expression.
Carnap pointed out that as long as philosophy is limited to the analysis of the logic and syntax of language, it can avoid problems related to objects, thus avoiding falling into solipsism. At the same time, determining whether a proposition is meaningful does not depend on whether it conforms to empirical facts, but on whether it is in the relevant language system. Phenomenalism and physicalism are two tendencies within the logical positivism of Vienna School, which can also be said to be two stages of its own evolution and development. Logical positivism holds that the task of philosophy is to make logical analysis of language, and one of the main purposes of logical analysis is to clarify the meaning of scientific concepts and propositions, thus laying the foundation for scientific knowledge. This raises a question, that is, what language should be chosen as the universal language of all scientific knowledge, or in other words, what language should be used as the basis of scientific knowledge. It is on this issue that there are differences between phenomenology and physicalism within logical positivism.
From the late 1920s to the early 1930s, phenomenology occupied a dominant position in logical positivism. Phenomenalism advocates the use of phenomenal language as the basis of scientific knowledge. Phenomenal language is a language based on personal subjective sensory experience. The basic feature of phenomenology lies in starting from feeling, direct experience, what it is and what it is, and taking subjective feeling experience as the basis of all scientific knowledge. They believe that subjective feelings and direct experience are self-evident and unquestionable, and do not need any test and proof, nor are they derived from any proposition. Therefore, all scientific propositions can be summed up in the final analysis as propositions expressing subjective sensory experience. According to phenomenology, the whole world is the logical structure of sensory experience, and all scientific knowledge is based on experience with the help of logic. Therefore, scientific knowledge should adopt phenomenological language based on sensory experience.
Physicalism came into being in the early 1930s, and its advocate was Newrat. Under his influence, Carnap quickly turned to physicalism. As a result, the debate between phenomenology represented by Shrek and weismann and physicalism represented by Newrat and Carnap emerged within the Vienna School. Physicalism advocates taking physical objects rather than sensory materials as the basis of scientific knowledge, and taking the physical language expressing physical objects as the universal language of all sciences, and tries to realize the unity of science on the basis of physical language.
Physicalism points out that everything that happens in the world is a part of nature, and it is all physical things and events. Therefore, the proposition that constitutes scientific knowledge should not be a feeling proposition that expresses personal direct experience, but a recorded statement that expresses physical events that everyone can observe. The language of feeling proposition is phenomenological, and the language of recording statement is physicalist. The so-called physical language refers to the language that people use to describe physical events in their daily life or physics. Because physical events are in a certain time and space, physical language is also a description of the time and space points of physical events. Physical language is characterized by the use of measurement concepts, such as temperature, speed, volume, specific gravity, pressure and so on.
Carnap pointed out that body language is universal and intersubjective. This is a physicalist argument. The reason why physicalism advocates using physical language as the universal language of all sciences lies in its universality and intersubjectivity. The so-called intersubjectivity means that subjects can understand and communicate with each other. For example, there is no need to argue about how long this blackboard is. Just measure it with a ruler. Phenomenon language does not have this, because it is based on personal feelings, and my feelings are incomprehensible to others, and vice versa, so phenomenon language is a private language that cannot be understood and communicated with each other. Carnap believes that one of the most important advantages of physicalist language lies in its inter-subject communication, that is, in principle, it enables all people who use this language to observe the events described in this language. Universality means that everything in the world can be expressed in physical language, because everything in the world is physical things and events. Physical language, that is, recorded statements about physical events, is not only applicable to physics, but also to all other disciplines.
Closely related to physicalism is the topic of scientific unity. Physicalism advocates using physical language as the basic language of all sciences. Newrat said: the unified language of unified science is the language of physics. Carnap also believes that the language of physics is the universal language of science, that is, any language in the field of science can preserve its original content and be translated into the language of physics. Committed to the unity of science is an important content of logical positivism of Vienna School. Carnap pointed out in his book Philosophy and Logical Syntax (1934) that all sciences can be separated for practical purposes, and they are all based on the same foundation. In the final analysis, they constitute a unified science. He also stressed that unifying science does not mean that the objects of all branches of science belong to the same category, but that the nouns of all branches of science are logically consistent. That is to say, in the view of logical positivism, unified science should be based on unified language.
The essence of the debate between phenomenology and physicalism is whether a proposition or sentence, as the basic language of all sciences, should be a phenomenological language to express sensory materials or a physical language to express physical objects. Newrat, Carnap and others think that phenomenology is methodological solipsism and physicalism is methodological materialism. Of course, changing from phenomenology to physicalism does not mean changing from idealism to materialism, because the difference between phenomenology and physicalism is only in the sense of methodology rather than ontology, and the essence of the difference lies in which language is more suitable as the basic language of science.