Language, Truth and Logic is a 1936 book about meaning by the philosopher Alfred Jules Ayer, in which the author defines, explains, and argues for the verification principle of logical positivism, sometimes referred to as the criterion of significance or criterion of meaning. Ayer explains how the principle of verifiability may be applied to the problems of philosophy. Language, Truth and Logic brought some of the ideas of the Vienna Circle and the logical empiricists to the attention of the English-speaking world.
According to Ayer's autobiographical book, Part of My Life, it was work he started in the summer and autumn of 1933 that eventually led to Language, Truth and Logic, specifically Demonstration of the Impossibility of Metaphysics—later published in Mind under the editorship of G.E. Moore. The title of the book was taken ("To some extent plagiarized" according to Ayer) from Friedrich Waismann's Logik, Sprache, Philosophie.[1]
Criterion of meaning
According to Ayer, analytic statements are tautologies. A tautology is a statement that is necessarily true, true by definition, and true under any conditions. A tautology is a repetition of the meaning of a statement, using different words or symbols. According to Ayer, the statements of logic and mathematics are tautologies. Tautologies are true by definition, and thus their validity does not depend on empirical testing.
Synthetic statements, or empirical propositions, assert or deny something about the real world. The validity of synthetic statements is not established merely by the definition of the words or symbols they contain. According to Ayer, if a statement expresses an empirical proposition, then the validity of the proposition is established by its empirical verifiability.
Propositions are statements that have conditions under which they can be verified. By the verification principle, meaningful statements have conditions under which their validity can be affirmed or denied.
Statements that are not meaningful cannot be expressed as propositions. Every verifiable proposition is meaningful, although it may be either true or false. Every proposition asserts or denies something, and thus is either true or false.
Types of verification
Ayer distinguishes between ‘strong’ and ‘weak’ verification, noting that there is a limit to how conclusively a proposition can be verified. ‘Strong’ (fully conclusive) verification is not possible for any empirical proposition, because the validity of any proposition always depends upon further experience. ‘Weak’ (probable) verification, on the other hand, is possible for any empirical proposition.
Ayer also distinguishes between practical and theoretical verifiability. Propositions for which we do not have a practical means of verification may still be meaningful if we can verify them in principle.
Literal meaning must also be distinguished from factual meaning. Literal meaning is an attribute of statements that are either analytic or empirically verifiable. Factual meaning is an attribute of statements that are meaningful without being analytic. Thus, statements that have factual meaning say something about the real world.
Ayer agrees with Hume that there are two main classes of propositions: those that concern 'relations of ideas,' and those that concern 'matters of fact.' Propositions about 'relations of ideas' include the a priori propositions of logic and mathematics. Propositions about 'matters of fact,' on the other hand, make assertions about the empirical world.
Ayer argues that philosophic propositions are analytic, and that they are concerned with 'relations of ideas.' The task of philosophy is to clarify the logical relationships of empirical propositions. If the meaning of propositions is defined by verifiability, then philosophy cannot provide speculative truths about metaphysical statements that cannot be empirically verified.
Metaphysics attacked
Ayer rejects the metaphysical thesis that philosophy can give us knowledge of a transcendent reality. He dismisses metaphysical arguments, calling them nonsense, and saying that they cannot be empirically verified. He argues that metaphysical statements have no literal meaning, and that they cannot be subjected to criteria of truth or falsehood.
A significant consequence of abandoning metaphysics as a concern of philosophy is a rejection of the view that the function of philosophy is to propose basic principles of meaning and to construct a deductive system by offering the consequences of these principles of meaning as a complete picture of reality. But this is, some may argue[who?], what Ayer does, in presenting the principle of verifiability as a criterion of meaningfulness for any empirical proposition.
According to Ayer, no proposition concerning "matters of fact" can ever be shown to be necessarily true, because there is always a possibility that it may be refuted by further empirical testing. Logical certainty is possible only for analytic observations, which are tautologies, and not for empirical observations concerning "matters of fact."
Ayer explains that his radical empiricism is opposed to rationalism. Rationalism asserts that there are truths about the world that can be known by a priori reasoning, or independently of experience. According to the principle of verifiability, propositions about 'matters of fact' can be meaningful only if they are capable of being empirically verified.
Ayer agrees with, and elaborates on, Kant's explanation of the distinction between analytic and synthetic judgments. According to Ayer, a proposition is analytic if its validity depends only on the definitions of the symbols it contains. A proposition is synthetic if its validity is determined by the facts of experience.
Analytic observations give us new knowledge, because they reveal unsuspected implications of our statements and beliefs. But analytic observations do not give us new knowledge of matters of fact, because they only tell us what is already known.
Truth as validation
Ayer defines truth as the criterion by which empirical propositions are validated. To say that a proposition is true is simply to assert it, and to say that a proposition is false is simply to assert a contradictory proposition. Thus, truth and falsehood are simply signs of assertion or denial of empirically verifiable propositions.
In the same manner, assertions of value have meaning only insofar as they are verifiable. If an ethical or aesthetic judgment cannot be subjected to empirical testing, then it is meaningless. An empirical test may be practical or theoretical.
For Ayer, ethical or aesthetic judgments are subjective rather than objective, and cannot be demonstrated to be true or false. Ethical or aesthetic judgments express feelings, not propositions, and have no objective validity. Value-judgments are not analytic, and are not verifiable as 'matters of fact.'
According to Ayer when we argue about whether a value-judgment is right or wrong, we are really arguing about the empirical facts on which a value-judgment is based, or about the logical interpretation of empirical facts. We cannot argue about something that cannot be expressed as a proposition. We can only argue about something that can be analytically or empirically verified.
For Ayer, metaphysical statements, such as statements about transcendent reality, have no objective validity, and therefore are meaningless. Examples of this lack of meaning include statements about the existence or nonexistence of God. According to Ayer, such statements can be neither proven nor disproven, and cannot be validated or invalidated by empirical testing.
New take on philosophy
Ayer's logical empiricism makes an important contribution to philosophy in that it provides a method of putting an end to otherwise irresolvable philosophical disputes. In Ayer's logical empiricism, philosophy is no longer seen as a metaphysical concern, it is not a search for first principles nor an attempt to provide speculative truths about the nature of ultimate reality. Instead, philosophy is seen as an activity of defining and clarifying the logical relationships of empirical propositions. In considering how to distinguish between a conscious man and an unconscious machine,[2] Ayer also anticipates the development in 1950 of the Turing test to test a machine's capability to demonstrate intelligence (consciousness).
The principle of verifiability, however, may become a means to arbitrarily reject any abstract or transcendent concept, such as “truth,” “justice,” or "virtue." Such concepts are seen as having no literal meaning. Thus, Ayer's viewpoint may become a radical scepticism. Ethics, aesthetics, and religion are all viewed as meaningless, as having no literal meaning. Ethical concepts are seen merely as expressions of feeling. Ethical or aesthetic concepts are seen as having no factual content, and therefore cannot be accepted as valid or invalid.
Ayer is careful to explain that the verification principle is a definition of meaning, and that it is not an empirical proposition. He admits that there are other possible definitions of meaning.
The most frequently expressed reservation about the principle is whether it is itself verifiable; this was addressed in the fictional dialogue "Logical Positivism: a discussion". Ayer believed that it could be derived analytically from usual definitions of words like "understanding". He admitted that one could then ask for verification of that definition and then carry on into an infinite regress. Ayer considered the latter option to be simply not worth consideration, although philosophers like Donald Davidson and Richard Rorty have since used it to undermine the concrete view of language found in works like Language, Truth and Logic.[citation needed]
Ayer's later rejection of logical positivism
Logical positivism was the philosophical flavour of the day in the 1920s and 1930s, and it was indeed popularized by Ayer in his book Language, Truth and Logic. However, Ayer himself later rejected much of his own work. Fifty years after he wrote his book, he said: "Logical Positivism died a long time ago. I don’t think much of Language, Truth and Logic is true. I think it is full of mistakes".[3]
Release details
By 2002, the book had been printed in twelve editions.[4] These included:
Sir Alfred Jules "Freddie" Ayer was an English philosopher known for his promotion of logical positivism, particularly in his books Language, Truth, and Logic (1936) and The Problem of Knowledge (1956).
In philosophy, empiricism is an epistemological view which holds that true knowledge or justification comes only or primarily from sensory experience and empirical evidence. It is one of several competing views within epistemology, along with rationalism and skepticism. Empiricists argue that empiricism is a more reliable method of finding the truth than purely using logical reasoning, because humans have cognitive biases and limitations which lead to errors of judgement. Empiricism emphasizes the central role of empirical evidence in the formation of ideas, rather than innate ideas or traditions. Empiricists may argue that traditions arise due to relations of previous sensory experiences.
In logic, the law of non-contradiction (LNC) states that contradictory propositions cannot both be true in the same sense at the same time, e. g. the two propositions "p is the case" and "p is not the case" are mutually exclusive. Formally, this is expressed as the tautology ¬(p ∧ ¬p). The law is not to be confused with the law of excluded middle which states that at least one, "p is the case" or "p is not the case", holds.
Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement whose central thesis is the verification principle. This theory of knowledge asserts that only statements verifiable through direct observation or logical proof are meaningful in terms of conveying truth value, information or factual content. Starting in the late 1920s, groups of philosophers, scientists, and mathematicians formed the Berlin Circle and the Vienna Circle, which, in these two cities, would propound the ideas of logical positivism.
Rudolf Carnap was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism.
Analytic philosophy is a broad, contemporary movement or tradition within Western philosophy and especially anglophone philosophy, focused on analysis. Analytic philosophy is characterized by a style of clarity of prose and rigor in arguments, making use of formal logic and mathematics, and, to a lesser degree, the natural sciences. It is further characterized by an interest in language and meaning known as the linguistic turn. It has developed several new branches of philosophy and logic, notably philosophy of language, philosophy of mathematics, philosophy of science, modern predicate logic and mathematical logic.
Emotivism is a meta-ethical view that claims that ethical sentences do not express propositions but emotional attitudes. Hence, it is colloquially known as the hurrah/boo theory. Influenced by the growth of analytic philosophy and logical positivism in the 20th century, the theory was stated vividly by A. J. Ayer in his 1936 book Language, Truth and Logic, but its development owes more to C. L. Stevenson.
Hume's fork, in epistemology, is a tenet elaborating upon British empiricist philosopher David Hume's emphatic, 1730s division between "relations of ideas" and "matters of fact." As phrased in Immanuel Kant's 1780s characterization of Hume's thesis, and furthered in the 1930s by the logical empiricists, Hume's fork asserts that all statements are exclusively either "analytic a priori" or "synthetic a posteriori," which, respectively, are universally true by mere definition or, however apparently probable, are unknowable without exact experience.
Logical atomism is a philosophical view that originated in the early 20th century with the development of analytic philosophy. It holds that the world consists of ultimate logical "facts" that cannot be broken down any further, each of which can be understood independently of other facts.
"Two Dogmas of Empiricism" is a paper by analytic philosopher Willard Van Orman Quine published in 1951. According to University of Sydney professor of philosophy Peter Godfrey-Smith, this "paper [is] sometimes regarded as the most important in all of twentieth-century philosophy". The paper is an attack on two central aspects of the logical positivists' philosophy: the first being the analytic–synthetic distinction between analytic truths and synthetic truths, explained by Quine as truths grounded only in meanings and independent of facts, and truths grounded in facts; the other being reductionism, the theory that each meaningful statement gets its meaning from some logical construction of terms that refer exclusively to immediate experience.
"Is Logic Empirical?" is the title of two articles that discuss the idea that the algebraic properties of logic may, or should, be empirically determined; in particular, they deal with the question of whether empirical facts about quantum phenomena may provide grounds for revising classical logic as a consistent logical rendering of reality. The replacement derives from the work of Garrett Birkhoff and John von Neumann on quantum logic. In their work, they showed that the outcomes of quantum measurements can be represented as binary propositions and that these quantum mechanical propositions can be combined in a similar way as propositions in classical logic. However, the algebraic properties of this structure are somewhat different from those of classical propositional logic in that the principle of distributivity fails.
Verificationism, also known as the verification principle or the verifiability criterion of meaning, is the philosophical doctrine which asserts that a statement is meaningful only if it is either empirically verifiable or a truth of logic.
Logical truth is one of the most fundamental concepts in logic. Broadly speaking, a logical truth is a statement which is true regardless of the truth or falsity of its constituent propositions. In other words, a logical truth is a statement which is not only true, but one which is true under all interpretations of its logical components. Thus, logical truths such as "if p, then p" can be considered tautologies. Logical truths are thought to be the simplest case of statements which are analytically true. All of philosophical logic can be thought of as providing accounts of the nature of logical truth, as well as logical consequence.
In mathematical logic, a tautology is a formula or assertion that is true in every possible interpretation. An example is "x=y or x≠y". Similarly, "either the ball is green, or the ball is not green" is always true, regardless of the colour of the ball.
The problem of religious language considers whether it is possible to talk about God meaningfully if the traditional conceptions of God as being incorporeal, infinite, and timeless, are accepted. Because these traditional conceptions of God make it difficult to describe God, religious language has the potential to be meaningless. Theories of religious language either attempt to demonstrate that such language is meaningless, or attempt to show how religious language can still be meaningful.
The analytic–synthetic distinction is a semantic distinction used primarily in philosophy to distinguish between propositions that are of two types: analytic propositions and synthetic propositions. Analytic propositions are true or not true solely by virtue of their meaning, whereas synthetic propositions' truth, if any, derives from how their meaning relates to the world.
A priori and a posteriori are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on experience. A priori knowledge is independent from any experience. Examples include mathematics, tautologies and deduction from pure reason. A posteriori knowledge depends on empirical evidence. Examples include most fields of science and aspects of personal knowledge.
Inductivism is the traditional and still commonplace philosophy of scientific method to develop scientific theories. Inductivism aims to neutrally observe a domain, infer laws from examined cases—hence, inductive reasoning—and thus objectively discover the sole naturally true theory of the observed.
Philosophy of logic is the area of philosophy that studies the scope and nature of logic. It investigates the philosophical problems raised by logic, such as the presuppositions often implicitly at work in theories of logic and in their application. This involves questions about how logic is to be defined and how different logical systems are connected to each other. It includes the study of the nature of the fundamental concepts used by logic and the relation of logic to other disciplines. According to a common characterisation, philosophical logic is the part of the philosophy of logic that studies the application of logical methods to philosophical problems, often in the form of extended logical systems like modal logic. But other theorists draw the distinction between the philosophy of logic and philosophical logic differently or not at all. Metalogic is closely related to the philosophy of logic as the discipline investigating the properties of formal logical systems, like consistency and completeness.
The descriptive fallacy refers to reasoning which treats a speech act as a logical proposition, which would be mistaken when the meaning of the statement is not based on its truth condition. It was suggested by the British philosopher of language J. L. Austin in 1955 in the lectures now known as How to Do Things With Words. Austin argued that performative utterances are not meaningfully evaluated as true or false but rather by other measures, which would hold that a statement such as "thank you" is not meant to describe a fact and to interpret it as such would be to commit the descriptive fallacy.
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