Language, Truth, and Logic Analysis

A. J. Ayer


(Student Guide to World Philosophy)

In Language, Truth, and Logic, Sir A. J. Ayer presents a modified version of logical positivism that he prefers to call “logical empiricism.” However, the doctrines, particularly their implications for philosophy, are largely those of logical positivism, and the work serves to bring these together succinctly and vigorously. Therefore, the book has had great importance as a positivistic document and as a center of controversy about positivistic tenets. In it, Ayer offers to solve the problems of reality, perception, induction, knowledge, meaning, truth, value, and other minds. He presents no great new idea; rather, he has modified and brought into logical consistency solutions proposed by others. In the introduction to the 1946 second edition, Ayer provided further explication and modified a few beliefs, but essentially his position remained unchanged.

The Verification Principle

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Ayer attacks metaphysics, saying that he will deduce the fruitlessness of attempting knowledge that transcends the limits of experience from the “rule which determines the literal significance of language.” The sentences of metaphysics, failing to meet this rule, are meaningless.

Ayer finds the criterion of meaning in the verification principle. “We say that a sentence is factually significant to any given person, if, and only if, he knows how to verify the proposition which it purports to express—that is, if he knows what observations would lead him, under certain conditions, to accept the proposition as being true, or reject it as being false.” Another possible kind of meaningful sentence is the tautology. However, any sentence that is neither a tautology nor a verifiable proposition (by this criterion) is a mere pseudoproposition, a meaningless sentence.

Certain provisions qualify this tenet. Ayer distinguished practical verifiability and verifiability in principle. Some sentences are not practically verifiable because of inconvenience or the present state of science and culture. If one knows what observations would decide such a matter if one were in a position to make them, the proposition is verifiable in principle. A further distinction is that between “strong” verifiability and “weak” verifiability. According to the “strong” theory, advanced by the Vienna Circle of logical positivists, a sentence is meaningful...

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(Student Guide to World Philosophy)

A common mistake is to assert that without a satisfactory analysis of perception, one is not entitled to believe in the existence of material things. Rather, the right to believe in their existence comes simply from the fact that one has certain sensations, for to say the thing exists is equivalent to saying the sensations are obtainable. The business of philosophers is to give a correct definition of material things in terms of sensations. They are not concerned with the properties of things in the world but only with how people speak of them. The propositions of philosophy are not factual, but linguistic in character: “They do not describe the behavior of physical, or even mental, objects; they express definitions, or the formal consequences of definitions.” Philosophy is a department of logic. It is independent of any empirical, not to say metaphysical, assumptions. Often propositions that are really linguistic are so expressed as to appear to be factual. “A material thing cannot be in two places at once” is actually linguistic, recording “the fact that, as the result of certain verbal conventions, the proposition that two sense-contents occur in the same visual or tactual sense-field is incompatible with the proposition that they belong to the same material thing.” The question “What is the nature of X?” asks for a definition, which is always a linguistic statement.

Philosophical analysis essentially provides definitions. However, such definitions are not the most frequently occurring kind, that is, explicit, or synonymous, definitions giving an alternative symbol or symbolic expression for the term to be defined. Rather, they are definitions in use, which are made by showing how a sentence in which the definiendum...

(The entire section is 728 words.)

Analytic and Synthetic Propositions

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Ayer adopts the distinction between analytic and synthetic propositions. Each has its own validation. “A proposition is analytic when its validity depends solely on the definitions of the symbols it contains, and synthetic when its validity is determined by the facts of experience.” While “Either some ants are parasitic or none are,” an analytic proposition, is undubitably and necessarily true, it provides no actual information about ants. As a tautology, it has no factual content and serves only to help us understand matters of language. The valid propositions of logic are true by tautology and are useful and surprising in revealing hidden implications in our sentences. They can help us gain empirical knowledge, but it is not the tautologies that render empirical knowledge valid. Whether a geometry actually can be applied to physical space is an empirical question that falls outside the scope of the geometry itself. There is therefore no paradox about the applicability of the analytic propositions of logic and mathematics to the world.

Synthetic propositions, Ayer affirms, are validated by experience. Experience is given in the form of sensations. Sensations are neither true nor false; they simply occur. Propositions about them are not logically determined by them in one way or another; hence, while these are perhaps largely dependable, they may be doubted. Similarly, they may be confirmed by additional experience. In other words, “Empirical...

(The entire section is 443 words.)

Statements of Value and Religion

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To account consistently for statements of value with empirical principles, Ayer holds that descriptive ethical sentences are empirical statements and that normative ethical sentences are “absolute” or “intrinsic,” not empirically calculable, and indefinable in factual terms. The normative symbols in a sentence name no concepts, add nothing to the factual content. Thus, normative sentences are not capable of being true or false. They simply express certain feelings of the speaker. They are not even assertions that the speaker has a certain feeling, for such assertions would be empirical and subject to doubt. Thus the question of their having any validity at all is removed.

How, then, can one dispute about value? Ayer maintains that actually one never disputes about questions of value but only about questions of fact. The pattern usual in such a dispute is to exhibit to one’s opponent what one believes to be the facts, assuming a common framework of value statements, and attempting to bring the opponent to one’s way of seeing the facts.

As to religious knowledge, one cannot appeal to tautologies for factual truth about God, for these are mere stipulations of one’s own. Nor can one have empirical propositions about God, for one can conceive of no experience that would bring one different sense-contents if God exists than if he does not. Hence, the notion is metaphysical and meaningless.

The Self and Knowledge of the World

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Ayer applies a complete phenomenalism to the traditional problems of the self and knowledge of the world. He denies that the given needs a logical rather than sensory justification. Further, he rejects the pattern of subject-act-object as an account of perception. He defines a sense-content not as the object but as a part of sense-experience, so that the existence of a sense-content always entails the existence of a sense-experience. Hence, the question of whether sense-contents are mental or physical is inapplicable. Such a distinction can apply only to the logical constructions that are derived from them. The difference between mental and physical objects lies in differences between the sense-contents, or in the different relations of sense-contents that constitute objects.

The self may be explained in similar terms. “It is, in fact, a logical construction out of the sense-experiences which constitute the actual and possible sense-history of a self.” To ask its nature is to ask what relationship obtains between sense-experiences for them to belong to the sense-history of the same self. Rather than retain the metaphysical notion of a substantive ego, one can identify personal identity simply in terms of bodily identity, and that in turn is to be defined in terms of the resemblance and continuity of sense-contents. To say anything about the self is always to say something about sense-contents. One knows other selves empirically, just as one knows physical things and one’s own self empirically.

Ayer urges the unity of philosophy with the sciences. Rather than actually validating scientific theory, the philosopher’s function is to elucidate the symbols occurring in it. It is essential to the task that the philosopher understand science. Philosophy must develop into the logic of science.


(Student Guide to World Philosophy)

As well as providing further exposition, Ayer’s introduction to the second edition contains some modifications of doctrine that deserve notice. In the interim between editions, he came to accept a belief of the logical positivists that he opposed in the first edition, that some empirical statements may be considered conclusively verified. These are “basic statements,” referring to the sense-content of a single experience, and their conclusive verification is the immediate occurrence of the experience to which they refer. As long as these merely record what is experienced and say nothing else, they cannot be factually mistaken, for they make no claim that any further fact could confute. However, this change makes little...

(The entire section is 481 words.)


(Student Guide to World Philosophy)

Additional Reading

Austin, J. L. Sense and Sensibilia. New York: Oxford University Press, 1962. A widely read response from an ordinary language perspective to A. J. Ayer’s early epistemological formulations. Austin dismissed Ayer’s views as “weak” and “full of jokes.”

Foster, John. The Philosophical Arguments of Philosophers: Ayer. London: Routledge and Kegan Paul, 1985. A systematic and detailed presentation of Ayer’s philosophical views as contained in his major works. A high-level work, but probably the most authoritative secondary source on Ayer’s views.

Griffiths, A. Phillips. A. J. Ayer Memorial Essays. Cambridge, England: Cambridge University, 1991. An excellent collection of commentaries on Ayer’s contributions to philosophy by those who knew him personally. Includes a British Broadcasting Corporation interview with Ayer conducted during the last year of his life.

Hahan, Lewis, E., ed. The Philosophy of A. J. Ayer. Library of Living Philosophers series. La Salle, Ill.: Open Court, 1992. Ayer responds to twenty-one of the twenty-four papers addressing his work. Also contains Ayer’s essay “My Mental Development” and a bibliography of his publications. The best survey of his life’s work.

Hanfling, Oswald. A. J. Ayer. New York: Routledge, 1999. An excellent biographical introduction to the thoughts of the philosopher, clearly presented and requiring no special background. Bibliography.

Hanfling, Oswald. A. J. Ayer: Analysing What We Mean. London: Phoenix, 1997. An examination of Ayer’s work and his contribution to philosophy.

MacDonald, G. F., ed. Perception and Identity: Essays Presented to A. J. Ayer with His Replies to Them. London: Macmillan, 1979. A set of essays honoring Ayer upon his retirement from Oxford, made more useful by the inclusion of his responses to each paper.

Magee, Bryan. Modern British Philosophy. New York: St. Martin’s Press, 1971. Interviews with leading British philosophers including A. J. Ayer and his early mentor Gilbert Ryle. A sound and easily understood presentation of Ayer’s views.

Priest, Stephen. The British Empiricists: Hobbes to Ayer. New York: Penguin Books, 1990. An excellent source for placing Ayer’s work in the tradition from which it emerged.