by Ted Honderich

After he got his B.A., Ayer did not doddle or get bogged down in research, but wrote a book immediately. Language, Truth and Logic is a lovely thing, and he had the good fortune to see it reprinted throughout his life. It is one of eight books of his republished in a library set under the title A. J. Ayer: Writings on Philosophy by the Palgrave Macmillan Archive Press. The collection needed an introduction. It follows here. If you are need of persuading of the diversity of opinions within philosophy, you may compare it with something else, an academic obituary composed for the British Academy. It is by the redoutable Anthony Quinton, scholar and peer of the realm.

     Alfred Jules Ayer was born in London on 29 October 1910 into  a well-connected family with a continental past, went to the great private  school Eton and then to Oxford, wrote the book Language,Truth and Logic when he was 24, and won celebrity for it and some notoriety. After serving in the war as an intelligence officer, he became the Grote Professor of the Philosophy of Mind and Logic at University College London, and then the Wykeham Professor of Logic at Oxford. He was a dutiful teacher, and in philosophical discussions he invigorated and indeed inspired students and younger colleagues. As a result of broadcasting on the BBC, he became the best-known of British philosophers, and was knighted. He was England's Logical Positivist. More than any of that, he was the greatest 20th Century philosopher definitely within a definable tradition of David Hume of the 18th Century, perhaps the greatest of philosophical traditions. 1 He was the antithesis of the philosopher of mystery and intimation, and he was not tempted to technicality. He lived assertively and was vain and cocksure -- at some cost to his philosophical reputation, since other philosophers were as human in their judgements on him. He was also honest, humane, and more or less on the Left in politics. He liked society, was a man of many women, came to be self-judging, and after some sadness died bravely, on 27 June 1989.

   If Ayer's connection to Hume is a matter of more than one fact, the heart of Language, Truth and Logic is a proposal with an antecedent in resolute and resonant words of Hume. They give philosophical expression to a hardheadedness and scepticism that also turn up elsewhere, certainly in much science and common sense.

If we take take in our hand any volume, of divinity  or school metaphysics for instance, let us ask, Does it contain any abstract  reasoning concerning quantity or number? No. Does it contain any experimental  reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion.2

  It is clear that both Hume and Ayer are concerned somehow to dismiss or demote all utterances that are neither necessarily true nor empirical -- utterances, as some say, that are neither logical or mathematical nor scientific. But it is not clear what Hume took their 'sophistry and illusion' to be, precisely speaking. It is not clear, either, to what extent his own philosophical practice and propositions require us to revise and loosen his two criteria for what is not sophistry and illusion.

  In speaking of necessarily true propositions, Ayer evidently has in mind  much more than the contents of formal logic and pure mathematics. He takes  it that all these necessarily true propositions are merely analytic. That  is, they are not made true by any necessities in the world, any natural necessities,  but just by meanings of words alone and the logical structures into which  they enter. 'Bachelors are unmarried' is an example. The other category of  propositions, roughly speaking, contains those that are are in a way empirically  verifiable -- some sense-experience is relevant to their truth or falsity.       

  The heart of Language, Truth and Logic, and of Logical Positivism, is indeed  the Verification Principle of Meaningfulness, which, in a wide understanding,  is to the effect that any utterance outside of these two categories is to  be dismissed as inferior and indeed hopeless.

  That leaves open the question of exactly what is wrong with such an utterance.  Ayer says various things, rather too many, in the original 1936 edition of  Language, Truth and Logic and in the introduction to the 1946 edition. An  utterance that does not satisfy the Verification Principle is said to be nonsense, literally senseless, not meaningful, not significant, without literal significance, not factually significant, a pseudo-proposition rather than a real one, not true or false. Some of the succes de scandale of the book, if not other success, was owed to the earlier usages in that sequence, as in the declaration that metaphysics, centrally understood as putative knowledge of a transcendent reality, and also religion and morality, are nonsense.

  Ayer was attracted to this rhetorical excess, and no doubt thought that it would make his readers think. But he would no doubt have allowed explicitly  in 1936, if the matter had been put to him, that 'Shut the door', which is  neither logical nor empirical, is certainly not nonsense or senseless, in  any ordinary understanding of those words. Presumbly he would have granted  explicitly, if pressed, as he came close to saying himself in 1946, that the Verification Principle is a principle that specifies no more than what utterances are actually true or false -- what things are propositions or statements strictly speaking, as those terms are used by many philosophers.

  The Verification Principle does not lose its philosophical force when so  understood. It cannot be much consolation to metaphysicians, religious believers  and many moralists to be reassured that their utterances are not gibberish,  if it is added that those utterances are neither true nor false -- that they  do not even come up to the level of being false.

  It needs to be remembered in this and other connections that Ayer's and Logical Positivism's whole enterprise does not ultimately have to do with language. The enterprise is certainly not linguistic analysis in a common understanding of that term. Its concern is with what language is about -- realities, as you can say. Some language purports to be about a transcendent reality, or God, or facts of the good and the right. To say that utterances that purport to assert or presuppose the existence of these things are not true or false is in effect to subtract these things from a prior and wider class of things: just possibly existing things, candidates for reality. To repeat, that can be no consolation to metaphysics, religion and morality -- or to aesthetics and other such practices of evaluation.

  Ayer very much gives the impression, sometimes says, that the Verification  Principle is a premise or basis from which there follows or on which there  rests the conclusion that metaphysics, morality and religion is neither true  nor false. If so, we need to know about the premise or basis. What can be  said for it? After all, it is not at all self-recommending, not near to the  truth that A is A or the truth that nothing is both X and not-X.

  Ayer promises at the beginning that his book will provide a demonstration  or proof of the Verification Principle. What he has in mind, evidently, is  a reflection in Ch. 5 on the very nature of the non-analytic propositions  that are admitted as respectable by the principle -- they are taken in themselves,  in their very nature, to be bound up with verification by sense-experience.  It is possible to think that this line of reflection is circular or begs the question.

  It is also possible to wonder, more radically, if the whole philosophical  situation in which we are involved by Ayer is otherwise. At any rate, is it better described in a very different way? Does the whole argument really go in the other direction? Might it be that the supposed premise or basis mentioned above is the conclusion, and the supposed conclusion is the premise or basis? That is, an examination without presupposition of particular utterances of metaphysicians, moralists and religious people shows the utterances to be other than propositions or statements, other than true or false. And this  is summed up in or provides good reason for the generalization that is the Verification Principle.

  Certainly you can read Chapter 6 of Language, Truth and Logic , 'Critique  of Ethics and Theology', in this way. At the centre of the chapter is the  line of thought that particular moral judgements are essentially expressions  of emotion or perhaps commands.

If now I...say 'Stealing money is wrong', I produce a sentence which has  no factual meaning -- that is, it expresses no proposition which can be either  true or false. It is as if I had written 'Stealing money!!' -- where the shape and thickness of the exclamation marks show, by a suitable convention, that a special sort of moral disapproval is the feeling which is expressed. It is clear that there is nothing said here which can be true or false.3

  Others, certainly, embrace the given idea about moral utterances directly,  without aid from any general principle. As for Ayer's lines, it is not as  if 'Stealing money is wrong' is first identified by some mark as a moral judgement, thereby taken as falling under the Verification Principle, and only then concluded to be neither true nor false. The simpler view, if it raises philosophical problems, is that when you look around there is no particular fact of the matter to be found to give a truth-value to 'Stealing money is wrong'.

   If you read Chapter 8, largely about metaphysics, there is the same possibility. The dispute between philosophical idealism and realism -- about whether, as idealism supposes, everything that exists is in some sense mental or spiritual -- is not approached with the Verification Principle in hand. Rather, it seems, the dispute is looked at directly, independently of the principle. So too with the metaphysical controversy between those who say reality is One and those who say it is Many, the Monists and the Pluralists. Each of the utterances 'All is One' and 'God exists' is something for which we are at least hard-pressed to find a fact that makes it true or false.

   There has of course been discussion of the basis of the Verification Principle, the possibility of a proof of it. Ayer himself enters into this question, as already noted. Can it be maintained, rather, that this is on the way to being as much beside the point or indeed confused as the idea that the generalization 'All men are mortal' rests on some general basis or proof distinct from individual facts of mortality, individual deaths?

   Whatever the direction of argument, and whatever the possibilities of two-way argument, which also need to be mentioned but cannot be considered here, there is another question about Ayer's Logical Positivism. So far we have it that the Verification Principle is that an utterance is required to be either analytic or, roughly speaking, empirically verifiable -- such that some sense experience is relevant to it. Good philosophy, however, goes beyond rough speaking. What is the Verification Principle precisely speaking?

   The 1936 edition of Language, Truth and Logic, mainly in the preface and first chapter, attempts an explicit statement of the principle. It became clear that it was open to objection by way of a logician's device, involving a conditional statement. In fact, by the use of the objection, the principle could be seen as allowing any utterance at all to be true or false. The 1946 introduction reports the objection and reformulates the Verification Principle. Unfortunately, however, this reformulation is open to a related objection. If the objection is very much a logician's, and invites the idea that it can be avoided by some further contrivance, this was not clearly demonstrated.

   The discussion of precise formulations of Ayer's principle and objections to them is of interest and importance, but cannot be set out here. Your best course of action, reader, here and elsewhere, is to turn to the best book on this philosophy, A. J. Ayer (1985) by John Foster. Its first chapter sets out clearly the details and possibilities with respect to precise understandings of the Verification Principle.

  Is it possible to think that there must be an understanding that is precise  and has the right consequences? I am inclined to that view, for a reason that you can anticipate. To the extent that the Verification Principle is a concluding generalization rather than a premise, it presumably is possible to state it explicitly in a way that makes it entirely distinct from the generalization that all utterances are true or false. To think that any attempt must fail in this way would be remarkable.

  Care will have to be taken in the descriptions of metaphysics, morals and  religion that go into the statement of the principle, care in specifying what is included in them, but that is to be expected. It could be, too, happily,  that some utterances, say about other minds or the thoughts and feelings of others -- other minds -- or about the past, turn out not to be condemned by the principle. Some philosophers have objected that they are, and taken this to be a great objection to the principle.

   We shall return in a way to Language, Truth and Logic . To turn now to two other books, The Foundations of Empirical Knowledge and The Problem of Knowledge, they take their departure from an argument that has run through much of the history of philosophy. It can be found in some form in the dusty archives of ancient Greek philosophy.

  It is an argument that has run, more particularly, through that large part  of philosophy that has to do with the question of the nature of the reality  of which we have experience -- as distinct from any reality that is a matter  of only theory. The part of philosophy in question can as readily and properly  be described, secondly, as having to do with our knowledge by way of sense  experience. So this is epistemology as well as what has been identified by  Peter Strawson as descriptive or analytic as against speculative or revisionary  metaphysics. Or, thirdly, rather to understate its claims and pretension,  this is the part of philosophy that consists in the problem of perception,  the analysis of our seeing, hearing and so on.

   The argument in question, you might say, has to do with what we actually experience as against what we habitually if unreflectively take ourselves to experience. What you actually experience, you can say, with respect to this very page you are reading, is different at different times, depending on light conditions and on the position of your head in relation to it. At the simplest level, the shape or approximate geometrical figure of what you have, is different on different occasions, depending on your relative position. It seems plain that these various experienced things, since they are different, must somehow not be one thing.

   Other examples can be added. There is, as we say, the stick that looks bent in water but straight out of it. To turn to other modes of sense perception, there is the different warmth of the water in the basin to a cold hand, and the different sound of a voice or a train to someone whose hearing is impaired.

   But is not the page itself one thing? Is that material thing not one thing? So with the stick and so on. Does it follow, then, that we do not perceive or experience physical things?

  Suppose, with respect to the page, that it is said that our being at one  particular angle to it gives us something we can call the page as it is, or the page itself, as distinct from something we can call a look of the page. The trouble is that there seems no difference in kind or type between the fact of experience owed to a particular angle and facts of experience owed to other angles. It is not as if there was a confirming click, so to speak, a message on the screen, when we see the page as strictly rectangular. Rather, there is what seems to be perfect continuity of sort or type between all of our different views or experiences of the page.

   To the ordinary facts at least tending in the direction of the idea that we do not experience physical objects can be added other reflections. One, which has much to do with the argument in question being known as the argument from illusion, does not concern ordinary perception but rather complete hallucination. Hallucinations do indeed occur, but we can usefully think of your hallucination, while in a completely dark room, or away from all pages, of seeing before you what you do in fact now see -- as we say, this page of this book. In this case of hallucination, it seems, your experience would or could be indistinguishable by you from what we call your actually seeing the page now. There could be no difference at all. That is, what you experienced in the dark room would have properties qualitatively identical to what you are now actually experinencing.

   The conclusion of the argument from illusion, to come finally to one statement of it, is that what we ordinarily experience, what we get by way of sense perception, is not reality. What we get is not what we call physical things, material objects, for the several reasons.

  There is but one of those that we both are said to perceive when, as we say, we see this page from different angles. The page itself, surely, does not change its shape under different conditions of perception. The reality itself of the temperature of the water does not depend on and vary with temperatures  of my hand. And, to come round to the complete hallucination or possible hallucination, where there is no page at all, something is experienced. It is not that there is no experience, that there is an experience of nothing. As remarked, what is experienced is in no way different from ordinarily seeing a page. What was experienced in the hallucination was not a page, and it follows that what you are now experiencing is not a page either. What you are now experiencing, to give it a name, is a sense-datum.

   The argument from illusion can be taken to issue in a bundle of questions. They can be arranged in a kind of ascending order. What is it, really, to do what we call see or otherwise perceive something? What do we actually experience and how is this sense-datum related to what we call reality, or at any rate ordinary reality? Are the things we experience, including the look of the page or the page as it looks to me now, the foundations of our knowledge of other things, the physical or material things that make up the external world? Are they necessary foundations? Are our beliefs in our sense-data certain, indubitable or incorrigible, unlike our beliefs in physical objects? Is there a closer relation than that of premise and conclusion between the things we experience and the other things? A different relation than premise and conclusion?

   That bundle of questions can only be answered after others, prior questions often slid by, as they were above, are considered first. What you heard before the bundle of questions was posed, the account of the argument from illusion, is itself thick with prior questions. To go back to the beginning of the account, what is it to actually experience something and what is it just to experience something? And what we experience -- exactly to what do those words refer?A little further on in the account, what is the page as it is? What is the fact of experience? How are we to understand these things? There are also other questions left open.

   In the two books, The Foundations of Empirical Knowledge and The Problem of Knowledge, Ayer carries forward what is surely the finest inquiry of his century into these matters. They are matters that are not at all simple. Certainly he makes advances on the clarity of Hume, and of John Stuart Mill, and on the Vienna Circle of Logical Positivists. He also brings into better and quicker focus certain lines of thought in the work of his contemporary, H. H. Price. If I may revert in passing to the subject of the man rather than his work, the credit he gives to Price is the action of a honest man. Authors have managed to conceal debts to one another before now.

   The first chapter of The Foundations of Empirical Knowledge is a deft inquiry into the structure, sides and aspects of the argument from illusion, and, above all, into what conclusion or conclusions can be drawn from it. The role of sense-data is inquired into with an acute persistence that maintains a momentum which itself serves understanding. One conclusion, in a bare sentence, is that the description of our relation to the world in terms of sense-data is an arguable alternative to the description in terms of material things. There are alternative languages here.

   The second chapter opens the questions left nearly closed in what you have heard from me so far. These have to do with the exact nature of sense-data, and the exact nature of material things. The third chapter has centrally to do with the seeming privacy or subjectivity of sense-data, so different from the seeming public nature of physical things, and with what can be taken to follow from this.

   Ayer's philosophy here is a phenomenalism, which is to say a working-out of the idea that physical objects are somehow or other to be understood in terms of private and indubitable sense-data. This theory is his second and principal conclusion in the book. It is close to the idea that physical objects consist in sense-data in the sense that physical objects are entities constructed by us in thought out of sense-data.

   This work, not his last on the subject, was the object of the only sustained attack on Ayer's philosophy. This was by another distinguished Oxford professor, J. L. Austin, in the book Sense and Sensibilia (1962). It is an attack by a philosopher who exemplified both what was called ordinary language or linguistic philosophy and also a notable cleverness. If it caused hurt to Ayer, it was surely conclusively replied to by him in the article 'Has Austin Refuted the Sense-Datum Theory?' Another philosopher of rank, to whom we will return in connection with the matter of Ayer's originality, Anthony Quinton, allows that Ayer shows that most of Austin's objections are captious.

   There is more in The Foundations of Empirical Knowledge than has been mentioned -- including a chapter having to do with causation and determinism in connection with perception. But let us pass on to what Ayer himself sometimes took to be his best book. It is The Problem of Knowledge, published in 1956 when his career as Grote Professor at University College London was near its zenith.

   What has been said already is nearly adequate as an introduction to it, but certainly it contains new thinking, theories that played no significant part in The Foundations of Empirical Knowledge.

   What is it to know something? That is no easy question. Ayer considers a number of conventional and tempting ideas, but comes to the succinct view that what it is for you to know something is for the proposition to be true, for you to believe it or be sure of it, and for you to have the right to believe it or be sure of it. It is a recommendation of this line of thought that it has been the point of departure for virtually all analyses of knowing since. It brings to mind that if it is mistaken, there are mistakes that advance philosophy, often because they put an idea or inclination clearly and forcefully. They are more important to progress in the subject than many contributions taken to have the recommendation of truth.

   Ayer's analysis of knowledge is a prelude to a new general view of the large subject-matter of The Foundations of Empirical Knowledge. This general view, which in fact covers more than that subject-matter, is located in a characterization of philosophical scepticism generally and of the possible responses to it.

  In a number of settings, we seem to find ourselves with certain beginnings,  premises, reasons, evidence or other beliefs, according to the sceptic, and  also with larger beliefs, so to speak, that are related to them. We have what we take to be records and other evidence now, in the present, for the general conclusion that events took place in the past -- that there were past events, as against any events in particular. We have what we take to be excellent reasons, having to do with the speech and other behaviour of other humans around us, for the general conclusion that they have conscious lives like our own, that they too have ongoing minds. In these two cases and others, it seems, we make a transition from or go beyond the data, and can do so on the basis of only the data, there being no other grounds for the transition.      

  The philosophical sceptic asks us for our justification. He points out that  there is a gap. That is, the data do not logically entail the supposed conclusions  -- it is not self-contradictory for me to accept as true all the propositions  about your behaviour that in fact make me believe you are conscious -- but  to doubt or deny that conclusion. Nor, it is said, is the conclusion produced  by induction, the method of science and much else. Such extrapolation or generalization from limited evidence of things going together cannot be got into operation with respect to the past and other minds. We never have particular experience of documents plus past, or the behaviour of others plus their consciousness in order to get started towards a general conclusion.

  As you will anticipate, the problem of reality, the reality we take ourselves  to know by way of perception -- or the problem of perception itself -- is  of the same pattern, and perhaps is clarified by the pattern. We begin, it  seems, with sense-data, which are private and fleeting items, and we propose  to end with material objects, public and lasting. Here too we face the challenge  of the sceptic. And, to proceed, the responses to the gap or supposed gap  are of the same sort as with the problems of the past and other minds.

  A first response with respect to the problem of reality is what Ayer refers  to as naive realism, and others have spoken of more tolerantly or respectfully  as direct realism. This view denies the initial proposition that we only have access to physical objects by way of our sense-data. Rather, to say we experience pages, in the most common understanding of the word, is simply true.

  A second response is what Ayer here calls reductionism. It is in fact a somewhat altered phenomenalism. Here, physical objects are again taken in a particular sense to consist of sense-data, to be in a way constructions of or a matter of sense data. Talk of the two sorts of things is somehow equivalent. There is an effort to deny the importance of the gap between data and conclusion. While the realist asserts we can somehow make it to reality without the problematic stepping-stone of sense-data, the reductionist or phenomenalist, in fact a very different philosophical character, has it that there is no gap to cross. Both of sense-data and physical things are on the same side of what is no more than an invented or imagined division.

  These and other philosophies of external reality, knowledge and perception  are looked into in uniquely instructive ways in a long chapter in The Problem  of Knowledge. The conclusion to which Ayer comes, to state it again briskly,  is that in referring to physical objects as we do, we are advancing or engaging  in a theory on the basis of the evidence of our senses -- a theory that has  no source or ground other than private sense-data but does go beyond them.  It is a particular kind of theoretical construction out of them. Distinguishing  this more fully from the view of Foundations of Empirical Knowledge is not  easily done, and cannot be done here. Again, if you are to come to have a  grip on the issue, lay hands on Foster's A. J. Ayer.

  As in the case of others of Ayer's books, The Problem of Knowledge has in  it more than is needed for its main theme or line of argument. It looks at  connected matters. In this case, there is a discussion of personal identity  -- of what makes a person now the same person as some person in some previous  year, maybe a boy or a girl. It is no easy question, and he advances it. There is also consideration of Descartes' cogito ergo sum, and the family of theories, later to become an orthodoxy for a time, that conscious or mental events are in fact only physical events.

  Ayer wrote more than many distinguished and great philosophers, even putting  aside his books that are not philosophy strictly speaking. The volumes now  before you contain almost all of his philosophical books. So far, what has  been provided in this introduction is a sketch of main parts of three of them, not so swift as to exclude a bit of philosophical reflection. These three together with one more are perhaps his finest books, despite the general excellence of all those still to be noticed. Unfortunately, in this hurrying world, we must now proceed in a less leisurely fashion.

  What is truth, or, to turn that question into one clearer one, what is it  for a proposition or statement to be true? The most familiar answer, blessed  by dictionaries, is that a true statement is one that corresponds to a fact  in the world. But what is such a fact? Is the fact that the croquet lawn is green as much in the world or of the world as the lawn itself, and maybe the greenness of the grass? You may wonder if the fact that the croquet lawn is green, like the lawn and the greenness, actually has a location. You may then come to wonder if a fact is itself a true statement. Do you now take up the idea that it is things and properties that true statements correspond to? If that is a very good idea, to my mind, what is the relation?

  Such difficulties are contemplated by Ayer in one of the papers collected  in the book The Concept of a Person and Other Essays (1963). He also considers  a quite different philosophical idea about truth. What is the answer to the  question, however it is related to the one above, of what it is that we understand  and state in stating that a statement is true? In saying a statement is true,  some say, what we do is just make that very statement. Nothing more is stated  by 'The statement that the lawn is green is true' than 'The lawn is green'.  The idea is coolly and well examined by him, on the way to a related but different position.

  Of several essays in the book directed at the thinking of other philosophers,  the best-known one, for good reason, has to do with Ludwig Wittgenstein's  declaration about the possibility of a private as against a public language  -- say a private language in which you use a term you think up in order to  refer to a private sensation. There can be no such language, according to  Wittgenstein, essentially because any utterance in a language depends on the use of signs such that there are independent tests for the signs being used correctly. As it seems to me and others, Ayer's direct responses silence or should silence this piece of philosophical audacity, almost as wonderfully  unlikely as Wittgenstein's declaration that there is no process in the brain  associated with thinking.

  In The Origins of Pragmatism, made up of two large studies of the American  philosophers Charles Peirce and William James, Ayer attends to subjects of  theirs which were also his. Certainly there were similarities as well as differences between Logical Positivism and Pragmatism, firstly in terms of the importance given to the verification of utterances. Peirce's developed doctrine of signs or representations, including their classification, was of clear interest to Ayer, and he clarifies it.

  To persist for a moment with the matter of truth, and hence with differences  rather than similarities, there was James's pragmatic theory of it to consider.  In it, he says that what is true is often whatever proves itself to be good  in the way of belief. Here he seems not far enough from the ideas that what  is true is what works, or gives us satisfaction, or satisfies us emotionally.  This is evidently not Peirce's idea, whatever is to be said of it, that the  true opinion in any matter is the one fated to be ultimately agreed by all  who investigate the matter.

  Ayer, as you may expect, does not tolerate James's way with truth. Still,  he works hard to find a somehow related theory that is more arguable. Here  and elsewhere he engages splendidly and to our great benefit not in philosophical  scholarship but in what can be called philosophical rectification and reconstruction  -- making a critical entry into another philosopher's thinking and then making  the best of it, finding the best version, before coming to alternative thinking  or a judgement.

  There is less need for this sort of thing, he evidently supposes, with Bertrand  Russell and G. E. Moore, the two great stalwarts of Cambridge philosophy -- Cambridge philosophy at its best, without visions and intimations, either  technical and abstract or literary and loose. His accounts of their philosophy  in Russell and Moore: The Analytical Heritage (1971) are without parallel  as wonderful expositions by a philosopher both in intimate connection with  a subject-matter and capable both of adding to it and maintaining his independence.

  Russell shared with a multitude of philosophers the conviction, surely indubitable,  that the meanings of at least many terms, say names and descriptions, somehow  or other are things for which they stand, things to which they refer. Or,  better, the meanings of these terms are somehow bound up with these things,  dependent on them. Is this not truistic with 'Alfred Jules Ayer'? Is it not  true of 'the present Queen of England'?

  That is all very well, but what of the terms 'the present king of France'  and 'the fountain of youth in Frome', or, if you share the beliefs of 51%  of the population of Britain on this day in 2004, 'the honest prime minister  of Britain today'? These are terms such that there is nothing, or many think  there is nothing, for which they stand -- they lack referents or reference.

  Russell's theory of descriptions, a formalized kind of culmination of much  of the philosophy of British empiricism, explains how such terms can be meaningful,  as plainly they are, despite their having no single referents. The very short  story is that all such terms, certainly including the ones that do have referents  in the ordinary way, owe their meaning to the fact that statements including  them, rightly understood, have a certain form and nature. 'The present king  of France is wise' is properly understood and analysed as 'There is something  which alone rules over France and which is wise'. In the analysis, you will  note, the description that causes trouble for a referential theory of meaning  is missing. Also, referents do exist with respect to those terms in the analysis  whose meaningfulness arguably depends on the existence of things.

  Ayer's introduction to Russell moves quickly to the theory of descriptions  and then beyond it. In the case of Moore, who so impressed Russell when they  were undergraduates together, Ayer's perfect exposition begins with Moore's  refutation, in its several parts, of the idealistic thrust of most speculative  metaphysics, that all of the universe with everything in it is somehow spiritual.  This called up Moore's defence of common sense and in particular a belief  in ordinary material objects. The best-known but not the most formidable part of his proof of the existence of material objects consists in the following  lines in a lecture.
I can prove now, for instance, that two human hands  exist. How? By holding up my two hands, and saying, as I make a certain gesture  with the right hand, 'Here is one hand', and adding, as I make a certain gesture with the left, 'and here is another'. 4

Ayer's discussion of this, and of the rest of Moore, is ideal in the main rather than the philosophical sense of the word.

   In 1972, he published Probability and Evidence. It begins with Hume, in this case with the problem that arises from the fact that most of the inferences on which we depend in our lives are not strictly deductive ones. Their premises do not entail their conclusions -- to accept the premises but deny the conclusions is not to fall into self-contradiction. Rather, they are inductive inferences, say that the staircase will continue to support your weight when you go up it.

   These are inferences from limited data to a general conclusion, or a particular conclusion derived from one. The data remains limited even if it is all the data so far. Plainly data of the form 'Some A's have been or are cases of B' cannot entail 'All A's are B's'. What then are these inferences -- and how is it that they are justified?

   Ayer proceeds through this real and great problem throwing a clear light on every side and aspect of it. I know of no better exposition of it in the history of philosophy, no better attempt to resolve it. It is at the level of the different attempt of Peter Strawson in his Introduction to Logical Theory (1952).

  It is superior to Karl Popper's supposed solution or dissolution, one of  whose salient weaknesses is the idea that the logical problem of how we get  to generalizations is somehow avoided if we take those generalizations as  somehow only tentative, corroborated or in a plain way probable, rather than  being proven truths -- despite the fact that we depend on them and indeed  trust our lives to them in every minute of the day. However, there is no more entailment between 'Some A's are B's' and 'That all A's are B's is corroborated'  than between 'Some A's are B's' and 'All A's are B's'. It needs adding that  Popper's related idea that science actually aims not at the confirmation of generalizations but at their falsification is, to say the least, no more useful -- as pointed out by Ayer in passing in The Problem of Knowledge (pp. 73-4).

   The related subject of probability, with its several competing theories, is as well considered in Probability and Evidence. In this discussion, as in the discussion of induction, there is a greater care taken than in Language, Truth and Logic. Probability and Evidence is perhaps Ayer's most technical book. It readily repays the attention and persistence that its subject requires. This is as true of its concluding part, on the troubled subject of such ordinary conditional statements as 'If the temperature of that water is raised another degree, it will boil', where the truth of the antecedent or 'if'-clause does not logically guarantee the conclusion. To come to a proper and full understanding of the truth of these instances of 'if P, then Q' is to come to an understanding of the nature of scientific laws, the nature of lawlike connections in the world.

   The Central Questions of Philosophy (1973) was published when Ayer was 63. It was put forward, partly, as an introduction to philosophy in the category where Russell's The Problems of Philosophy had reigned supreme. It takes up philosophical problems that the world and our existence in it force on us clearly, not contrived or elusive or unformed problems. But this impressive book, the fourth of his finest ones,  is more than an introduction. It is an admirable retrospect of Ayer's own work, indeed his own introduction to it. Yet more important, it takes matters forward.

   It returns to the concerns passionately written of in Language, Truth and Logic, including morality and religion, it reconsiders or at any rate looks again at nearly all of Ayer's subsequent positions and supporting arguments. It therefore has to do with more subjects than have got into this introduction to his work. Some are closer to logic, say the understanding of claims that two things are identical. Some are closer to descriptive metaphysics, say the question of the way in which abstract entities like numbers can be said to exist. There is more on that crux of the philosophy of mind, the mind-brain relation. There are brief culminations of his thinking on the existence of real chance as against determinism, which oddly, like Peirce, he defended. There are thoughts on the meaning of life.

   Above all, there is an advance in his thinking about reality, knowledge and perception. There is a unique departure from phenomenalism, which does indeed have the disability of imprisoning each of us in a private world, in favour of a realism, if not naive realism. Ayer outlines a procedure of understanding whereby we begin not with private and subjective things but with neutral ones -- items that are not physical objects either. Through a procedure involving imagination rather than deduction, we come to what are called visuo-tactual continuants, then to physical objects, and finally to private phenomena. Sense-data come last, not first. He was proud of this line of argument, rightly.

   Taking all of his career, how great a philosopher was Ayer? You heard an opinion from me at the beginning of this introduction to his work. More needs saying. First, some philosophical naivete needs to be put aside.

   It is possible to conjecture, you will remember, that Language, Truth and Logic raises and does not answer a very basic question about itself: Is the Verification Principle a premise or a conclusion? You will remember, too, that the book itself does not provide a final statement of the principle. Are these dispiriting facts? Are they such as to put in question the achievement of Language, Truth and Logic?

   One simple way to approach that question is by way of mighty Hume himself. Among his main contributions to philosophy, one example, was his analysis of causation. What it is at bottom for B to have been an effect of A, he concluded, as he is usually if not always understood, is at bottom for all events like A to be followed by events like B. This, like all of Hume's great contentions, is at least disputed. Its enticing simplicity has not carried the day, and to my mind the contention can be disproved. The beginning of the disproof can be the fact that tonight is not the effect of today. On reflection, Hume's contention is also unclear, in its idea of like events.

  We can also think of the equally great Kant, and his doctrine of the unknowable  noumenal world, something nonetheless known to exist behind or under the ordinary world we experience. This is fundamental to much of his philosophy. It is certainly disputed, and certainly it calls out for clarification, indeed for rescuing from seeming self-contradiction. Uses of the doctrine, further, for example in allowing for free will despite the determinism of the knowable  phenomenal world, are baffling -- we are tempted to say merely baffling.

  The conclusion must be that great philosophy does not depend on being the  discovery or defence of propositions made perfectly clear and known thereafter  to be true. That conclusion also follows, of course, from the fact that pieces  and whole traditions of great philosophy are plainly inconsistent. And yet  philosophy does have to do with truth on large subjects. It is a kind of general logic aimed at truth. So the short story of its nature, I think, must be that great philosophy, to some large extent, consists in great mistakes -- greatly valuable mistakes, enlightening and fertile mistakes in a progress  towards truth.

  Ayer, to my mind, despite what can be said in objection to Language, Truth  and Logic, played a large role in that progress by way of that book.

   Here is another fact relevant to the book's standing and that of its author. As you have heard, the book was published in 1936, republished after the war in 1946. After that there was little or no speculative metaphysics in the mainstream of English and American philosophy, whatever there was elsewhere. No doubt that report can only be made clear by moving towards and laying out a definition of speculative metaphysics.

  Merely to conjecture for a moment, a good definition will take speculative  metaphysics to be speculation as to a transcendent reality, probably speculation  of an aspirational character, certainly speculation that brings to mind the  large metaphysicians of the past, mostly philosophical idealists. It will  be at the other end of a scale from naturalisms. Speculative metaphysics will not include, for example, the analysis of conditional statements in terms of the mere assertion of possible worlds, or a consideration of such fundamental ontological categories as those of particulars and properties, or the idea that what it is to be perceptual aware of the room you are in is for the room in a way to exists.

  If it would be rash to the point of silliness to set out to explain the decline of speculative metaphysics only by Ayer's book, it would also be rash to exclude it from the explanation or set of causes. The mtter is not an easy one. It is hard to weigh causes, hard to think of a method of weighing them. But some things are clear. If both the book and its reception and the demise of speculation about a transcendent reality are to an extent owed to some other prior set of conditions, say the war itself and a change in philosophical attitudes, that can leave Language, Truth and Logic with a greater philosophical effect than any book of philosophy in the 20th Century. Later causes are not non-causes.

  Certainly it is it as if all mainstream philosophers who carry on their work in English have been persuaded by the book, or by others persuaded by the book. The same cannot be said, say, of the works of Wittgenstein. To my mind, there is no general fact of philosophy, no large retreat or advance, such that a book of his requires to be included in the explanation of it. This is perhaps as true of the books of better philosophers than him in my estimation, philosophers akin to Ayer in terms of a certain cool outlook not susceptible to desirous speculation or to visions, say Strawson or W. V. O. Quine.

   Ayer's standing as a philosopher has occasionally been qualified by way of the idea that in general he was not a highly original thinker. It has been remarked or conjectured that Language, Truth and Logic is owed to what he learned from the Logic Positivists of the Vienna Circle when he spent four months in Vienna at the age of 22 after finishing his Oxford degree.

  Lord Quinton, himself a philosopher of formidable powers, as witnessed for  example by his work The Nature of Things (1973), has in one of two philosophical  obituaries5  justly said that Language, Truth and Logic, in style, economy  and capacity to excite, ranks somewhere near Descartes' Meditations and Berkeley's  Principles. That is no small or medium-sized recommendation. He also speaks  of Ayer's philosophical courage, transparency of argument, destructive and  lethal criticism of Wittgenstein and others, and of his being, by certain  comparions, a marvelous champion of the best traditions of rational discourse.  Also noted, as relevantly, is Ayer's unwillingness simply to report views  of others. As against all this, however, Lord Quinton meticulously sets out  details of what he speaks of as Ayer's derivativeness, his acquisitions from  other philosophers.

   That any 22-year-old philosopher learns a lot from powerful thinkers among whom he finds himself, and makes use of what he has learned, can be no surprise. Something like it is the experience of virtually all graduate students in philosophy, including those who go on to be the leading lights of the subject. Are they therefore bound to be unoriginal in their first book? That does not follow. As for mature philosophers, are all of them merely derivative who take up ideas from their contemporaries? Things need thinking about here. A certain quick judgement would certainly consign 22-year-old and mature philosophers across whole philosophical industries, say the current philosophy of mind in its physicalism, to something too near to the standing of copy-cat.

   In a conclusion, Lord Quinton writes of Ayer as follows.

He was undoubtedly one of the liveliest figures  on the British philosophical scene in his time and, when he appeared on it,  it was in need of enlivening. He was not a highly original thinker. His impact  was due to the brilliance with which he arranged and expressed the ideas he had acquired from others. Perhaps his greatest intellectual virtue was his unremitting adherence to clarity and to rational argument. His work is without allusions, undeveloped suggestions, obscurity, and mannerism. Through his books and his teaching he sets a fine example of intellectual discipline.6

    It is possible to think, as I do, that giving supreme clarity,  order and rationality to a set of views, brilliantly, supposing for a moment  that only this is done by a philosopher, is itself a matter of originality.  Evidently it may be something never done before. It may be the unprecedented  achievement of rescuing, making available and preserving what would or might  otherwise be undervalued or lost. So too is transparency of argument, conclusive  criticism and supreme intellectual discipline a matter of originality. To  repeat, it is not as if others have done already what is now done by means  of these powers. It is not as if what exists now existed before.

   Let me add that we need to remember that it is plain that originality as sometimes thought of is not enough and in fact not our subject-matter. This originality is not enough in a philosopher or anyone else in any line of life. That is, it is not enough to be independent of other people's ideas, to be inventive and unusual, to be unimitative. Any idiot can be that. This mere originality in philosophy, whatever reputation is had got for smaller and larger figures. even celebration or veneration or anticipated immortality, has done nothing much for philosophy.

   What we want in philosophers and others, to revert to a line of thought, is the originality that actually is more truth conveyed or more progress towards truth -- or perhaps more excellence of a related kind conveyed or moved towards, as in painting and much of the rest of art. This originality consists in seeing, choosing and expressing truth or an approximation to it, giving its nature in the representation of it, shaping and colouring the representation rightly.

  All of that, including the seeing and choosing, is necessarily a matter of style, economy, clarity, criticism, transparency of argument, and the like. I am inclined to add in courage, certainly intellectual character, and a capacity to excite and enliven. In short, more truth conveyed or more progress towards it is evidently something inseparable from powers granted on all sides to have been superlatively possessed by Ayer -- powers granted indeed by Lord Quinton.

   All these comments together on form and content, on what is mistakenly divided into form and content, do not do more than begin a discussion of originality. They do begin one. I am confident, myself, that the end of such a discussion will not be unfortunate for A. J. Ayer. Let me now turn briefly to something connected to this matter.

   It was said at the beginning of these reflections that Ayer is the greatest 20th Century philosopher within a definable tradition of David Hume in the 18th Century, and that this is arguably the greatest of philosophical traditions. The tradition can be understood in a certain way.

   It has in it certain problems, those that are forced upon us by the world and our common existence in it and thus are not factitious. As important as any among these problems are those spoken of earlier as having to do with reality, knowledge and perception. Also, this tradition is one of clear-headed reasoning, something carried forward in the light of experience and of theory close to it, not given to flying above it or being as visionary about what lies under it. It is definitely not performance-philosophy.

   Further, this tradition is not one of any specialism, but of the use of our shared intelligence, including our moral intelligence, in a general way. It is not just the philosophy of science or of mathematics or any other department that makes a contribution to the subject of philosophy. It is not obscured or constrained by formalisms, or by science, whatever good use it makes of them.

   There is a reason for saying this is perhaps the greatest of philosophical traditions. The reason has to do with the nature of all that counts as philosophy. I take it that all philosophy, however lyrical or rigourized, is general logic applied to large questions, where general logic is prior to and is not significantly advanced by formal logic and mathematics. Most of the large questions are questions to which science brings another excellence, while also attending to myriad smaller questions. This general logic on large questions, as you will understand, includes not only descriptive but also speculative metaphysics, and also, certainly, moral and political philosophy and more, even the philosophy of religion.

   As it seems to me, Hume's tradition, which was not his invention and might have another name, is the elemental and central project within philosophy as a whole. This particular tradition stands to philosophy, you might say, as the horse stands to equines. It is, you might say, a species of thinking that is the genus brought to a fruition.

   Of this particular tradition, I say with as much confidence as these matters allows, Ayer was the leader and exemplar in the 20th Century. Perhaps the largest other candidate is Russell. It is my own view, with has partly to do with the tradition's standing above specialism and formalization, that he stands as a great second to Ayer.

   No doubt postscripts are needed.

   It is not necessary to this judgement of Ayer's greatness, as you may anticipate,  that Ayer's philosophy is now paid as much attention as, say, Quine's. To  be cited today but not tomorrow is a common fate of philosophers, scientists,  novelists and others. There is the fact of fashion in philosophy,7 and of  oversight corrected later. It needs to be remembered that Hume was passed  over for the chairs of philosophy at Edinburgh and Glasgow, and that little  was heard thereafter of Mr. Cleghorn and Mr. Clow, deemed to be his superiors.  It is also to be kept in mind, say, that the hegemony of American philosophy  is not eternal, that American philosophers have not been transformed as philosophers  by an ascendancy that has to do with the ascendancy of their country.

   Another kind of postscript is also needed. My proposal about Ayer is one that must be owed in some part to affection, loyalty to him and a kind of philosophy, philosophical passion, and no great confidence in convention.7 But such humanity, such human failing if you like, is widely distributed. Other facts of it, including a conventionality that does not go well with the nature of all philosophy, are to be found in other philosophical judgements on behalf of other philosophers.


Books of philosophy by Ayer that could not be included in the volumes surveyed above are Philosophical Essays (1954), Metaphysics and Common Sense (1969), Freedom and Morality and Other Essays (1984), The Meaning of Life and Other Essays (1990). His books of commentary on philosophers are Hume (1980), Philosophy in the Twentieth Century (1982), and Wittgenstein (1985).

The best full account of his philosophy, as remarked above,  is John Foster's. Also of value are the papers by many philosophers in four  books: The Philosophy of A. J. Ayer (The Library of Living Philosophers Volume  XXI, 1992), edited by Lewis Edwin Hahn; A. J. Ayer: Memorial Essays (1991),  edited by A. Phillips Griffiths; and those in the Festschrift, Perception  and Identity (1979), edited by G. F. Macdonald; and Fact, Science and Morality  (1986), edited by Crispin Wright and G. F. Macdonald. In the Hahn and Macdonald  books, Ayer replies to each paper enlighteningly.

Ayer's autobiographies are Part of My Life (1977) and More  of My Life (1984). The admirable biography A. J. Ayer: A Life (1999) is by  Ben Rogers.

There is a 27-page bibliography of Ayer's writings, including  such more popular works as Voltaire (1986) and Thomas Paine (1988), and many  papers and other writings by him, in The Philosophy of A. J. Ayer, edited  by Hahn. 



1. I am grateful indeed for comments on a rather too early draft of this account of Ayer's philosophy to Justin Broackes, John Foster, Alastair Hannah, Jonathan Lowe, Mark Sainsbury and Peter Strawson in particular, but also to Sophie Allen, John Campbell, David Cooper, Tim Crane, Roger Crisp, James Garvey, John Haldane, Ingrid Honderich, Hugh Mellor, Paul Noordhof, Anthony O'Hear, David Papineau, Paul Snowdon, Timothy Sprigge and Patricia Walsh. We are not in agreement, but there is more support for or tolerance of my estimate of Ayer's standing than I expected.

2. David Hume, An Enquiry Concerning Human Understanding, ed. L. Selby-Bigge, p. 163

3. Language, Truth and Logic (Penguin Books, 1971), p. 110. Readers of other editions can find the remark a few pages into Ch. 6.

4. Moore, Philosophical Papers (1959), p. 146.

5. 'Ayer's Place in the History of Philosophy', in A. J. Ayer: Memorial Essays, noted in the bibliography, and 'Alfred Jules Ayer, 1910-1989', 1996 Lectures and Memoirs, Proceedings of the British Academy 94.

6. 'Alfred Jules Ayer, 1910-1989', pp. 281-282.

7. David Hamlyn, 'Fashion in Philosophy', Oxford Companion to Philosophy , ed. Ted Honderich.

8. Not discipleship, however. See On Consciousness (Edinburgh University Press, 2004), and articles in the books edited by Hahn and Phillips Griffiths.


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