A. J. Ayer

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Western Philosophy
20th-century philosophy
Name: Alfred Jules Ayer
Birth: October 29, 1910
Death: June 27, 1989
School/tradition: Analytic
Main interests
Language, Epistemology, Ethics, Meaning
Notable ideas
Logical positivism, verification principle, emotivist ethics
Influences Influenced
Hume, Vienna Circle, Popper, Russell, Wittgenstein, Kant R. M. Hare, Strawson

Sir Alfred Jules Ayer (October 29, 1910 – June 27, 1989), better known as A. J. Ayer (or "Freddie" by his friends), was a British philosopher known for his promotion of logical positivism, particularly in his books Language, Truth and Logic (1936) and The Problem of Knowledge (1956).

As a logical positivist, Ayer narrowed the sphere of philosophical inquiry only to the realm of logic, mathematics, and the empirical sciences, and denied the validity of all other spheres of knowledge, including metaphysics, religion, and traditional ethics. In this sense, Ayer shared the skepticism of Hume and followed a Humean division of knowledge (Humean view: knowledge is divided into logic, mathematics, and empirical knowledge while the rest is meaningless). Accordingly, for Ayer, both the “existence of God” and “non-existence of God” are meaningless claims since they are neither empirically verifiable nor statements of logic.

Thus, Ayer kept an atheistic position. However, a few years before his death, he had a near death experience. Although he did not publicly acknowledge the change of his views concerning the existence of God and the life after death, he was greatly affected by this experience. One wonders, if Ayer had this kind of experience at an earlier stage of his life, would he have taken a different approach in his philosophy?

Life of Ayer

Ayer was born in London, into good circumstances, but to a family that was only partly assimilated to English life. His father, Jules Louis Cypress Ayer, was a French-speaking Swiss Calvinist from Neufchatel, who had lived in England since moving there to join his mother at the age of 17. In 1909 he had married Reine Citroen, who was of an Ashkenazi Jewish family from Holland. Her uncle Andre set up the Citroen car firm, and her father, David, was also in the car business. The grandfather appears to have been a larger presence in A. J. Ayer's early life than Jules.

Young Ayer was precocious. From age seven he was sent to boarding school, and when he was 13 he won a scholarship to Eaton, where he was known as being both highly intelligent and highly competitive. He said of himself that he had an "unguarded tongue and propensity for showing off," traits that he would bear throughout his life. He felt himself an “outsider” at Eaton, and that feeling remained with him throughout his life. This feeling apparently came partly from his Jewish heritage and partly from his militant atheism; at Eton he attempted to convert his fellow students to atheism. At sixteen he read and was highly impressed by Bertrand Russell’s Sceptical Essays and G. E. Moore’s Principia Ethica. From Russell he adopted the view that it is wrong to believe a proposition to be true when there is no grounds for believing in its truth.

In 1928 he traveled to Paris where he met Renee Lees, whom he married in 1933. In 1929 he won a classics scholarship to Christ Church College of Oxford University. There he studied Greek and philosophy. One of his tutors was Gilbert Ryle, who suggested that he read Ludwig Wittgenstein’s Tractatus Logico-Philosophicus. This work caused Ayer to travel to Vienna in 1933 to meet with Moritz Schlick, the leader, and other members of the Vienna Circle of logical positivists. Along with W. V. O. Quine, Ayer was one of only two English-speaking people to meet and study with the Vienna Circle. Ayer was fluent in French but his German was not good; it was sufficient, however, for him to grasp the main points of logical positivism.

In 1935 Ayer was elected to a five-year research fellowship at Christ Church. That was also the year he finished writing Language, Truth, and Logic. While at Christ Church he refined his thought and had meetings with Isaiah Berlin, Stuart Hampshire, and J.L. Austin; he would have a long running controversy with Austin about sense data until Austin’s death. During this time he produced the book, Foundations of Empirical Knowledge. Also during this time his marriage to Renee began to disintegrate and Renee began an enduring relationship with Stuart Hampshire.

Ayer became strongly involved in politics in the pre WWII years, supporting the Republican side in the Spanish Civil War. He considered joining the Commnist Party, but became instead an active member of the British Labour party. He joined the Welsh Guards when WWII broke out and worked for a time interrogating prisoners. He was then sent to America on a secret service mission having to do with gaining information about Fascist sympathizers in America. While in New York he reviewed films for the Nation, and also maintained an active social life; he fathered a daughter with Sheila Graham and made a recording with Lauren Bacall. After returning to England he worked in organizing the French resistance in London, and then was sent to Paris; while there he studied French existentialism and wrote articles on Sartre and Camus.

After his army service he was a tutorial fellow for a short time at Wadham College, Oxford, and then became the Grote Professor of Philosophy at University College of the University of London, where he appointed Hampshire (whom Ayer had cited as co-respondent in his divorce form Renee) and Richard Wollheim to lectureships. During Ayer's time there University College grew and became a strong center of philosophy. Ayer also became involved in radio broadcasts, including discussions with the scientists Zuckerman, Huxley, and Medawar; he also held a well-known radio debate with the Jesuit historian of philosophy Frederick Copleston on logical positivism and the meaning of religious language. (Bertrand Russell also had a famous radio debate with Copleston on the existence of God.)

In 1948 C. E. M Joad published an article that claimed that Language, Truth, and Logic was responsible for creating an environment that favored Fascism, and Time magazine published an article attacking Ayer. For his part, Ayer embarked on a several years long lecture tour that took him to France, Belgium, Italy, Sweden, Denmark, Peru, Chile, Uruguay, and Brazil; this tour took place in the early '50s.

In 1958 Ayer became the Wykeham Professor of Logic at Oxford. He took the position in part, he claimed, to combat the strong influence of Oxford ordinary-language philosophy professor John L. Austin, who attacked Ayer’s views on perception; Austin died soon after (on February 8, 1960, at the age of 59). Ayer spent weekdays in Oxford and weekends in London with his second wife, Dee Wells. He continued to travel, including to China, Russia, India, and Pakistan. In 1963 he and Dee Wells had a son, Nicholas, whom Ayer loved dearly. But in Oxford he had a relationship with Vanessa Lawson. During the time from 1968 to 1983 he was also extremely productive philosophically, publishing a number of books (at least 4 of them) and giving the William James lectures at Harvard (1970), the Dewey Lectures at Columbia (also 1970), the Gifford Lectures at the University of St. Andrews in Scotland, the Gilbert Ryle lectures at Trent University in Canada (1979) and the Whidden lectures at McMaster (also in Canada, 1983).

Ayer was known for taking a very active interest in the work and studies of his students, and in helping them find jobs after they completed their degrees.

Ayer married Vanessa Lawson in 1982, shortly after being divorced from Dee Wells. Renee, his first wife, had died in 1980, followed by the death of their daughter, Valerie, in 1981. But Vanessa too died in 1985, leaving Ayer grief-stricken. This led to his remarrying Dee Wells, who comforted him in his grief and his old age.

A few years before he died, Ayer himself had a near death experience lasting for some four minutes while his heart stopped in his hospital bed after he choked on a piece of smoked salmon. Ever after that incident there has been a continuing controversy about whether Ayer’s experience during that episode converted him from lifelong atheism and unbelief in an afterlife to the opposite view – Ayer himself denying this publicly, but one of his doctors and others averring that Ayer had given private indications otherwise. In any case, Ayer’s wife Dee said that Ayer’s personality and behavior changed as a result of this. "Freddie became so much nicer after he died," she said. "He was not nearly so boastful. He took an interest in other people."

In addition to his philosophical work and his numerous marriages, Ayer had many love affairs and many sexual liaisons and a very active social life. He was a good dancer, and is supposed to have once said that he would have preferred being a dancer to a professional philosopher, but gave up that idea when he realized he would never be as good as Fred Astaire. His circle of acquaintances included W. H. Auden, Alan Bennett, Isaiah Berlin, Cyril Connolly, Richard Crossman, e. e. cummings and his wife Marianne, Jane Fontaine, Michael Foot, Hugh Gaitskell, Graham Greene, Christopher Hitchens, Roy Jenkins, Somerset Maugham, Jonathan Miller, Iris Murdoch, George Orwell, V. S. Pritchett, Stephen Spender, Philip Toynbee, Angus Wilson, and many others. The character George Moore in Tom Stoppard’s play Jumpers may have been modeled on him. It has been said of Ayer that “he was a vain man whose vanity was part of his considerable charm.”

Ayer served as a visiting professor at Bard College in the fall of 1987. According to a published account, at a party that year held by fashion designer Fernando Sanchez, Ayer, then 77, confronted Mike Tyson who was harassing the model Naomi Campbell. When Ayer demanded that Tyson stop, the boxer said: "Do you know who the fuck I am? I'm the heavyweight champion of the world," to which Ayer replied: "And I am the former Wykeham Professor of Logic. We are both pre-eminent in our field. I suggest that we talk about this like rational men". Ayer and Tyson then began to talk, while Naomi Campbell slipped out.

Among many other honors, Ayer was made a Fellow of the British Academy, an honorary member of the American Academy of Arts and Sciences, a Member of the Bulgarian Order of Cyril and Methodius, and Chevalier of the Legion d’Honneur (of France).

Ayer entered the hospital with a collapsed lung in the early summer of 1989 and died on June 27.

Although, by the time of Ayer's death, the Anglo-American philosophical world had largely moved from analytic to post-analytic philosophy, Peter Strawson stated at his memorial service—probably with some hyperbole—that Ayer's contributions were "in no way inferior to Russell's."

Language, Truth, and Logic

Ayer continued in the line of British empiricism that began with John Locke and David Hume and that had reached its pre-Ayer zenith with Russell. Ayer rejected the possibility of any synthetic a priori knowledge, holding (with other empiricists) that all knowledge is either analytic a priori or synthetic a posteriori. Mathematical and logical truths or facts, according to this view, and in opposition to the view of Immanuel Kant, are tautologies; they do not give us any synthetic information about the world.

While a student at Oxford Ayer read Wittgenstein’s Tractatus and was much impressed with it. In 1933 Ayer traveled to Vienna to meet and study with the members of the Vienna Circle. The result was Ayer’s first book, begun when he was only 24 and published when he was 26, Language, Truth, and Logic. After its publication this small book became the most studied and probably most influential treatise in philosophy in the Anglo-American world up to sometime in the 1950s. As Ayer himself noted in the Introduction to the second edition (1946) it was “in every sense a young man’s book,” and “much of its argument would have been more persuasive if it had not been presented in so harsh a form.” The book presents a summary of and strong argument for logical positivism. In that sense it can be called the gospel tract of logical positivism, or logical empiricism as Ayer preferred to call it.

Chapter one deals with the elimination of metaphysics and the adoption of verifiability. "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." Although no proposition can be conclusively verified, “For a statement of fact to be genuine some possible observations must be relevant to the determination of its truth or falsehood.” If no such observations "can be discovered, we must conclude that the sentence under consideration does not...express a genuine question, howeer strongly its grammatical appearance may suggest it does." Metaphysical sentences, defined as sentences that express neither tautologies (i.e. logic or mathematics) nor empirical hypotheses, are to be regarded as meaningless and nonsensical.

Chapter two deals with the function of philosophy. Philosophy, according to Ayer, is not a search for first principles. Instead, its function is wholly critical analysis, and it is wholly independent of metaphysics. “The philosopher as analyst is not concerned with the physical properties of things, but only with the way in which we speak about them.”

Chapter three is concerned with the nature of philosophical analysis. Philosophy gives not explicit definitions, but definitions in use. According to Ayer, “Material things are logical constructions out of sense-contents.” This solves, Ayer held, “the so-called problem of perception.” And “The propositions of philosophy are not empirical propositions…” but “are concerned with the logical consequences of linguistic conventions.”

Chapter four presents Ayer’s rejection of any synthetic a priori. “As empiricists,” he says, “we must deny that any general proposition concerning a matter of fact can be known with certainty to be valid.” The propositions of logic and mathematics are not inductive generalizations, as John Stuart Mill had claimed, but are instead “necessarily true because they are analytic.” Moreover, “Analytic propositions are tautological; they say nothing concerning any mater of fact. But they give us new knowledge, inasmuch as they bring to light the implications of our linguistic usages.”

In chapter five, Ayer asserts, “The words ‘true’ and ‘false’ function in the sentence simply as assertion or negation signs.” “No empirical propositions are certain, not even those which refer to immediate experience.” And “Observation confirms or discredits not just a single hypothesis but a system of hypotheses.”

Chapter six takes up the issues of ethics and theology. Assertions of value, Ayer claims, are not scientific, but are “emotive.” Thus they are neither true nor false. “They are partly expressions of feeling, partly commands.” The same applies to aesthetics. Concerning theology, it is impossible to demonstrate the existence of a transcendent god, or even showing it to be probable. So the assertion that a transcendent god exists is a metaphysical assertion, “and therefore not literally significant.”

Chapter seven is concerned with the self and the common world. There Ayer claims that the self should be analyzed in terms of sense experiences; that there are no a priori objections to the existence of epistemological and causal connections between minds and material things; that “a sense-experience cannot belong to the sense-history of more than one self,” that “the substantive ego is a fictitious metaphysical entity,” and that the claim “that the empirical self survives the dissolution of the body is a self-contradictory proposition.” He also denies that his view involves solipsism.

In the final eighth chapter Ayer dealt with his solutions to some outstanding philosophical disputes. He concludes with remarks on the relationship between philosophy and science; his view is that the philosopher must become a scientist “if he is to make any substantial contribution towards the growth of human knowledge” in that philosophy “must develop into the logic of science.”

In the second edition Ayer modified some of his positions to some extent. In particular, he wrote that he now considered it incorrect to say that there are no philosophical propositions. He also had come to believe that “there is a class of empirical propositions of which it is permissible to say that they can be verified conclusively.” He also dealt with and modified his handling of the problem of what he had earlier called “putative propositions” and propositions that “purport to express” something; with the fact that “most empirical propositions are in some degree vague,” and with his earlier claim that “philosophical analysis consisted mainly in the provision of ‘definitions in use.’”

Other Works by Ayer

In his book, The Foundations of Empirical Knowledge (1940), Ayer presented an account of knowledge that translates sentences about material objects into a sense-datum language. This view was famously criticized by J. L. Austin in Sense and Sensibilia, a landmark 1950's work of ordinary language philosophy. Austin responded in a 1967 journal article, “Has Austin Refuted the Sense-Data Theory?”

In 1954 Ayer published a book entitled Philosophical Essays; this was a collection of essays by Ayer that had appeared in various philosophy journals from 1945 to 1953. These essays deal with individuals, the identity of indiscernibles, negation, the terminology of sense-data, basic propositions, phenomenalism, statements about the past, one’s knowledge of other minds, what there is (i.e. what exists, or ontology), the analysis of moral judgments (a restatement of Ayer’s emotivism), the principle of utility (an examination and rejection of Jeremy Bentham’s notion of utility), and freedom and necessity (Ayer’s examination of determinism).

Ayer’s 1956 book, The Problem of Knowledge, deals with philosophy and knowledge, skepticism and certainty, perception and sense-data, memory, and one’s knowledge of other minds. It can be thought of as a recapitulation and refinement of, and an addition to, some central points made earlier in Language, Truth, and Logic.

The Concept of a Person and Other Essays, published in 1963, contains some previously published essays by Ayer as well as some new ones. Among other things, he deals with philosophy and language and linguistic philosophy; Tarski’s concept of truth; the earlier and later views of Wittgenstein; the question whether there can be a private language; the privacy of mind in contrast with the public nature of matter; the concept of a person, including P. F. Strawson’s claim in his book Individuals that the concept of a person is a primitive concept (i.e. one that cannot be analyzed into simpler components); names and descriptions, including Russell’s and Strawson’s views on that topic; the concept and supposed problem of truth; probability; the question what is a law of nature; and our knowledge of the past and future, and fatalism.

Besides his own work, Ayer produced numerous critical studies of the work of other philosophers. In 1968 he published The Origins of Pragmatism. In 1971 his Russell and Moore: The Analytical Heritage was published. In 1972 his book Bertrand Russell appeared. In 1980 he published his study of David Hume, entitled simply Hume. In 1986 his work on Wittgenstein, Ludwig Wittgenstein, was published. He was both attracted to and repelled by different things in both the early and late Wittgenstein; he liked Wittgenstein’s realism, but not what he called his “irrealism,” and he rejected Wittgenstein’s private language arguments; nevertheless he held Wittgenstein to be of all 20th century philosophers second only to Russell in “brilliance and originality.”

Besides those books mentioned above, Ayer published Metaphysics and Common Sense (1969); Probability and Evidence (1972); The Central Questions of Philosophy (1973); Philosophy in the Twentieth Century (1982), in which he claimed that philosophy in the twentieth century advanced and centered on the study and evaluation of evidence, and that other styles or forms of philosophy are either contributors to epistemology or else misguided; and Freedom and Morality and Other Essays (1984). He also published two autobiographies: Part of My Life (1977), and More of My Life (1984).

Ayer's Legacy

The range of Ayer's philosophical interests was somewhat narrow. As Anthony Quinton has noted, Ayer paid no attention to Plato and Aristotle or to anyone else earlier than William James and Charles Sanders Peirce. "His initial and, to a large extent, lasting preoccupation," Quinton wrote, [was] "with the theory of knowledge...." Quinton continued, "There was a certain narrowness to Ayer's mind which focused it sharply and contributed to its force. His lack of interest in ancient philosophy ... was part of a general indifference to the history of the subject," an indifference shared generally by Anglo-American analytic philosophy. "[Ayer's] interests were restricted in space as well as in time, being mainly confined to the English-speaking world and to the Vienna of the 1930s." And "Theory of knowledge was first and foremost, and, within it, the philosophy of perception in particular, but also our knowledge of the past and of other minds. Beside that he addressed himself at length to philosophical logic (the nature of necessity at first and later to reference, identity, truth, existence, negation, and the nature of individuals), the philosophy of mind (personal identity, the ownership of experiences), probability and induction, ethics (in a very generalised and schematic fashion), and the issue of the freedom of the will." Quinton also wrote of Ayer, "He was a philosopher of religion only in the sense that a dynamiter is an architect." But Quinton also remarks, "Nevertheless, the fields he cultivated were the most philosophically fertile of his epoch, in part, no doubt because of his work in them, and the philosophers to whom he gave his attention were those who pre-eminently deserved it."

Ayer is noted for a clarity of style and presentation and for an ability to expose and explain a philosophical problem or difficulty in a few sentences or paragraphs of clear prose. Whatever deficiencies the analytic and positivists schools of philosophy may have had – and Ayer himself in later life is supposed to have remarked about Language, Truth, and Logic that it was “all wrong” – they had the admirable virtues of clarity and logical rigor (something sorely lacking in most of the Continental philosophy of Hegel, Edmund Husserl, Martin Heidegger, and nearly all of their followers).

Moreover, Ayer can be faulted for failing to understand or appreciate post-analytic philosophy. In an essay entitled "After Empiricism," Hilary Putnam has criticized Ayer's Philosophy in the Twentieth Century. Putnam says that, "If any problem has emerged as the problem for analytic philosophy in the twentieth century, it is the problem of how words 'hook onto' the world." Putnam continues, "The difficulty with A. J. Ayer, who has tried ... to sum up Philosophy in the Twentieth Century is that there is no acknowledgement of the difficulty of this problem." Putnam says that Ayer got the first half of the twentieth century right, but not the second. Ayer's description of Wittgenstein's Tractatus is, Putnam says, "pleasant and useful to read," but "It is obvious that something happened in philosophy after the Tractatus with which Ayer is profoundly out of sympathy. ... The result is that the reader who had only this book to go by would have to see philosophy after the early Wittgenstein as, for the most part, a series of empty and confused ideas and arguments."

Ayer's philosophical ideas were deeply influenced by those of the Vienna Circle and David Hume—Hume too is noted for a clear and forthright style—and Ayer should be seen as following in the path of Hume. Ayer's clear, vibrant and polemical exposition makes Language, Truth and Logic continue to be essential reading on the tenets of logical positivism—the book is regarded as a classic of twentieth-century philosophy, and is still widely read in philosophy courses around the world.

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Primary Sources

  • 1936, Language, Truth, and Logic. London: Gollancz. (2nd. Edition, 1946)
  • 1940, The Foundations of Empirical Knowledge. London: Macmillan.
  • 1954, Philosophical Essays. London: Macmillan.
  • 1957, “The conception of probability as a logical relation”. in S. Korner, ed., Observation and Interpretation in the Philosophy of Physics. New York: Dover Publications.
  • 1956, The Problem of Knowledge. London: Macmillan.
  • 1963, The Concept of a Person and other Essays. London: Macmillan.
  • 1967, “Has Austin Refuted the Sense-Data Theory?” Synthese vol. Xviii, pp. 117-40. (Reprinted in Ayer 1969).
  • 1968, The Origins of Pragmatism. London: Macmillan.
  • 1969, Metaphysics and Common Sense. London: Macmillan.
  • 1971, Russell and Moore: The Analytical Heritage. London: Macmillan.
  • 1972a, Probability and Evidence. London: Macmillan.
  • 1972b, Bertrand Russell. London: Fontana.
  • 1973, The Central Questions of Philosophy. London: Weidenfeld.
  • 1979, “Replies”, in G. Macdonald, ed., Perception and Identity. London: Macmillan.
  • 1980, Hume. Oxford: Oxford University Press
  • 1982, Philosophy in the Twentieth Century. London: Weidenfeld.
  • 1984, Freedom and Morality and Other Essays. Oxford: Clarendon Press.
  • 1986, Ludwig Wittgenstein. London: Penguin.
  • 1977, Part of My Life. London: Collins.
  • 1984, More of My Life. London: Collins.

Secondary Sources

There is a vast literature on Ayer, logical positivism, ethical emotivism, and other topics covered by Ayer. Here are some of those works:

  • Altham, J. 1986. “The Legacy of Emotivism,” in Macdonald and Wright, 1986.
  • Austin, J. L. 1962. Sense and Sensibilia. Oxford: Clarendon Press.
  • Blackburn, S. 1984. Spreading the Word. Oxford: Clarendon Press.
  • Blackburn, S. 1998. Ruling Passions. Oxford: Clarendon Press.
  • Chalmers, D. 2004. “Epistemic Two-Dimensional Semantics.” Philosophical Studies 118 (1-2): 153-226.
  • Church, A. 1949. “Review of Language, Truth, and Logic.” Journal of Symbolic Logic 14: 52-53.
  • Foster, J. 1985 A.J. Ayer. London: Routledge.
  • Gettier, E. L. 1963. “Is Justified True Belief Knowledge?” Analysis 23 (6).
  • Gibbard, A. 1990. Wise Choices, Apt Feelings. Oxford: Clarendon Press.
  • Griffiths, A. P. 1991. A.J. Ayer Memorial Essays. Cambridge: Cambridge University Press.
  • Hahn, L. E. 1992. The Philosophy of A.J. Ayer. Open Court.
  • Hanfling, O. 1999. Ayer. London: Routledge.
  • Hawthorne, John (ed.). 2004. Ethics, Volume 18. Philosophical Perspectives series. Oxford and Malden, MA: Blackwell.
  • Honderich, T. 1991. Essays on A.J. Ayer. Cambridge: Cambridge University Press.
  • Jackson, F. 1998. From Metaphysics to Ethics. Oxford: Oxford University Press.
  • Lewis, D. K. 1988. “Statements Partly About Observation.” Philosophical Papers 17: 1-31.
  • Macdonald, G. F. 1979. Perception and Identity. London: Macmillan.
  • Macdonald, Graham and C. Wright. 1986. Fact, Science, and Morality. Oxford: Blackwell.
  • Mackie, J. L. 1977. Ethics: Inventing Right and Wrong. Harmondsworth: Penguin.
  • Martin, R. 2000. On Ayer. Wadsworth Publishing Co.
  • Putnam, Hilary. 1984. "After Ayer, After Empiricism." Partisan Review 51 (2). Reprinted in John Rachjman and Cornel West, eds., Post-Analytic Philosophy. New York: Columbia University Press, 1985.
  • Rogers, Ben. 1999. A.J. Ayer: A Life. Grove Press. ISBN 0802116736
  • Smith, M. 1986. “Should We Believe in Emotivism” in Macdonald and Wright, 1986.
  • Stevenson, C. L. 1944. Ethics and Language. New Haven, CT: Yale University Press. (The classic presentation of ethical emotivism.)
  • Thau, M. 2004. “What is Disjunctivism?” Philosophical Studies 120: 193-253.
  • Wilks, C. 2002. Emotion, Truth and Meaning. Dordrecht: Kluwer Academic Publishers.
  • Wright, C. 1986. “Scientific Realism, Observation, and the Verification Principle” in Macdonald and Wright, 1986.
  • Wright, C. 1989. “The Verification Principle: Another Puncture - Another Patch.” Mind 98: 611-22.

External links

All links retrieved June 13, 2023.

General Philosophy Sources


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