I am very much honoured to have been asked to make the closing speech at this Conference. Since this is the first time for over fifty years that a philosophical congress of this scope has been held in England, I hope that you will think it suitable for me to devote my lecture to the revival of the empiricist tradition in British philosophy during this century. I shall begin by examining the contribution of the Cambridge philosopher G. E. Moore. Though he first owed his fame to his book Principia Ethica (Moore, 1903) regarded as a work of genius by the Cambridge Apostles and their associates in Bloomsbury, who did not venture to question Moore's mistaken view of ‘good’ as an unanalysable non-natural quality, his reputation now chiefly rests on his subsequent defence of common sense.

I have told elsewhere the story of my first meeting with Freddie Ayer, but I shall re-tell it. It made a great impact on me, though, I believe, none on him. Certainly at no point in our friendship did he ever bring it up.

It was mid or late 1946. I was an undergraduate at Balliol, having returned from three years in the army, and I was reading for Part II of the History Schools. Most of my friends, most of my intellectual friends, were reading philosophy, and there was a necessity, which I already sensed, for my returning to Oxford once again to follow in their footsteps. This happened later in the autumn of 1947. Post-war Oxford was a very different place from the Firbankian hothouse of wartime Oxford, at least as I knew it. We were all said to be ‘more mature’, but within the confines of austerity, we were determined to enjoy ourselves. Oxford was not, in the famous words that Max Beerbohm put into the mouth of Mrs Humphrey Ward, ‘wholly serious’.

When A. J. Ayer arrived in Oxford in the autumn of 1929 he had no thought of becoming a professional philosopher. He intended to go to the Bar, but, in the manner of an Etonian, by way of Literae Humaniores rather than the study of law. He had read a couple of philosophical books. The first of them was Russell's Sceptical Essays (Russell, 1928), which he bought on its first appearance in 1928. The other was Principia Ethica (Moore, 1903), to which he had been led by a reverent aside in Clive Bell's Art (1914). These choices were significant. Ayer always thought of himself as Russell's successor. He modelled his thought on that of Russell, both in its content and in its unguarded expression and also, to some extent, his manner of life, both political and amorous. What he got from Moore is less obvious, although his respect for Moore is evident, as is shown by the preface to Language, Truth and Logic and by his devoting a book to a close examination of his ideas, along with those of Russell. An important likeness is that both Moore and Ayer were provoked to philosophize by the assertions of other philosophers, not by problems arising outside philosophy in mathematics or the sciences, in history or everyday life.

In an article contributed to Mind in 1934, the young A. J. Ayer declared war on metaphysics, claiming that his destruction of the metaphysicians' arguments rested on the establishment of the sheerly non-sensical character of their statements. Their errors were syntactical; the combination of symbols in the sentences with which they expressed their propositions violated fundamental principles of significance.

As we all know, in Freddie Ayer's famous book Language, Truth and Logic metaphysics received short shrift. Metaphysical assertions were dismissed as being all nonsensical (LTL, 2nd edn, 41). In the work in question Ayer clearly tended to equate metaphysics with what Professor W. H. Walsh was to describe as ‘transcendent’ (as distinct from ‘immanent’) metaphysics (Walsh, 1963). This tendency is also discernible, I think, in the 1949 debate between Ayer and myself on logical positivism. After all, my defence of metaphysics was largely prompted and certainly strengthened by what I believed to be the religious relevance of metaphysical philosophy. A lot of what Aristotle would have described as ‘first philosophy’ and what some later philosophers would have classified as ‘ontology’ Ayer would have called ‘philosophical analysis’. What he was primarily concerned with undermining was any claim by metaphysicians to be able to extend our knowledge of what exists, of the Absolute or God for example, by metaphysical arguments.

Some books are like parents, grandparents or old friends. They have been with us from our earliest days and one treats them almost with familiarity. They belong to one's youth and the recognition that they have been around for months and years keeps company with surprise. For philosophers such a book is A. J. Ayer's Language, Truth and Logic, first published over fifty years ago in 1936. There is a sense in which a similar point may be made about some individuals, but discretion and good manners should deter us from succumbing to the philosophical disease of pressing an analogy too far. Suffice it to say that over a period during which most English speaking philosophers were content (or perhaps constrained) to work within a context which was significantly influenced by Ayer's clear and cajoling formulation of a twentieth century of empiricism, F. C. Copleston provided one of the few distinctive alternative philosophical perspectives on major metaphysical questions. This essay will reflect upon the influence of Ayer's Language, Truth and Logic some fifty years after its publication, upon the philosophical discussion of religion and theological questions.

Among A. J. Ayer's many influential contributions to philosophy are the accounts of the nature of metaphysics which he propounded at various stages of his philosophical development. Whereas his early position is a clear version of the antimetaphysical attitude of the Viennese circle and, more generally, of logical positivism, his later position is, as he generously emphasized, in some crucial respects indebted to Peirce's pragmatism and to Ramsey's analysis of the structure of theories. His later views on the nature of metaphysics are contained in his book Central Questions of Philosophy and in his reply to my criticisms in a Festschrift, published on the occasion of his retirement from the Wykeham Chair of Philosophy at Oxford University (Macdonald, 1979). Although in this reply he describes his later account of metaphysics as ‘much too perfunctory’, it does constitute an important attempt at answering one of the central questions of philosophy.

When ‘Freddy’ Ayer asked me to contribute to his volume in the Library of Living Philosophers series (which, regrettably, has still not been published), I was delighted, and while the main topic of my contribution was the sense (if any) in which it can be a ‘necessary’ truth that water is H2O, I devoted a section of that essay to problems that I saw with Ayer's account of the paradigm intentional notion, the notion of reference. Ayer ended his reply by saying that he could not satisfactorily meet my objections, and with characteristic modesty and good humour he added that it was only small consolation that, in his opinion, no one else could satisfactorily account for reference either. The thoughtfulness, fairness, and responsiveness of Ayer's entire reply reminded me of the way in which the same qualities were displayed in Carnap's reply to my contribution to his volume in the same series. These two replies—Carnap's and Ayer's—display the virtues of the philosopher who searches for truth, and who genuinely welcomes serious criticism, in a truly exemplary way. I treasure both of them, and they are bound up with my memories of those two wonderful philosophers.

Our knowledge of the world comes to us, one way or another, through our senses. I know there's a table here, because I see it, and that there's traffic outside, because I hear it. And similarly for our other senses. I know when it's cold, because I feel it; when there's sugar in my tea, because I taste it; smoke in the air, because I smell it; and so on.

It is the business of philosophy to deal without presupposition with the question of the general nature of the world and with the question of how or indeed whether we can know that nature. These are questions to which answers are given in the realism of ordinary belief, as it can be called, the phenomenalism of Berkeley, the pragmatism and the scientism of Quine, and the varieties of scepticism. The ontological and the epistemological questions are bound up with another, that of the nature of perception—the question of what it is, in general, that happens when we perceive. What is called naive realism is an answer, as are representation theories, and phenomenalism again. If the question might be better defined, so as to distinguish it from the related scientific question, it is no matter of mere conceptual analysis. Let us start with this question of the nature of perception.

I know, for the most part, what I think, want, and intend, and what my sensations are. In addition, I know a great deal about the world around me. I also sometimes know what goes on in other people's minds. Each of these three kinds of empirical knowledge has its distinctive characteristics. What I know about the contents of my own mind I generally know without investigation or appeal to evidence. There are exceptions, but the primacy of unmediated self-knowledge is attested by the fact that we distrust the exceptions until they can be reconciled with the unmediated. My knowledge of the world outside of myself, on the other hand, depends on the functioning of my sense organs, and this causal dependence on the senses makes my beliefs about the world of nature open to a sort of uncertainty that arises only rarely in the case of beliefs about my own states of mind. Many of my simple perceptions of what is going on in the world are not based on further evidence; my perceptual beliefs are simply caused directly by the events and objects around me. But my knowledge of the propositional contents of other minds is never immediate in this sense; I would have no access to what others think and value if I could not note their behaviour.

Every week of term, on Wednesday afternoons, during most of his years at University College, Ayer held a seminar. Strangely, he makes no mention of that seminar in his autobiography, although it was a more serious and productive affair than his Monday evening seminar, which he does mention. At the Wednesday seminar, conditionals were often the subject for discussion. They are intriguing things in themselves but the attention they received must have been due, in large part, to their central role in Ayer's philosophy. Ayer was a phenomenalist, but he did not go so far as that prince of phenomenalists, George Berkeley, and assert that the things around us in space, chairs and tables, trees and rocks and lakes, the sun, moon and stars, were sensations, sensations of various kinds. Ayer's view was more that of John Stuart Mill, that these things were permanent possibilities of sensation. To assert the existence of a lake was to assert that if certain characteristic sensations occurred, then certain other characteristic sensations would follow. In that way, conditionals played a central role in Ayer's phenomenalism. That phenomenalism, however, needed to agree with an even more central element of his thought, the positivism he derived, perhaps from the philosophy of the Vienna Circle, perhaps from David Hume. According to that positivism, experience sets limits to understanding. If we can experience nothing but the presence or absence of sensations, then propositions concerning the presence or absence of sensations are all we can understand. Now a conditional concerning sensations does not imply the presence of sensations and, although it does imply the absence of sensations, it implies more besides. What Ayer's phenomenalism required, his positivism could not allow.

In 1936, in a chapter of Language, Truth and Logic clearly influenced by Hume (though inconsistent with Hume) and influenced also (Ayer later conjectured) by Ogden's and Richards's The Meaning of Meaning (1923), Ayer claimed that judgments of value, in so far as they are not scientific statements, are not in the literal sense significant but are simply expressions of emotion which can be neither true nor false. To say ‘You acted wrongly in stealing that money’ is not to state any more than one would have stated by merely saying ‘you stole that money’. To add that the action was wrong is not to make a further statement about it, but simply to evince one's moral disapproval. ‘It is as if I had said “you stole that money” in a peculiar tone of horror, or written it with the addition of some special exclamation mark. The tone or the exclamation mark adds nothing to the literal meaning of the sentence. It merely serves to show that the expression of it is attended by certain feelings of the speaker’ (LTL, 107).

Bertrand Russell said more than once that he was uncomfortable about a conflict, as he saw it, between two things: the strength of the conviction with which he held his ethical beliefs, and the philosophical opinions that he had about the status of those ethical beliefs—opinions which were non-cognitivist, and in some sense subjectivist. Russell felt that, in some way, if he did not think that his ethical beliefs were objective, he had no right to hold them so passionately. This discomfort was not something that Ayer noted or discussed in his account of Russell's moral philosophy and ethical opinions, at least in the book that he wrote for the Modern Masters series (RS). Perhaps this was because it was not a kind of discomfort that Ayer felt himself. His own philosophical views about the status of ethics were at all periods at any rate non-cognitivist, and I think that he did not mind them being called ‘subjectivist’. He did indeed argue that the supposed difference between objectivism and subjectivism in ethics did no work, and that philosophers who took themselves to be objectivists could not achieve anything more than those who admitted they were subjectivists. Ayer based this mainly on the idea that the claims made by objectivists for the factuality, objective truth, and so forth of moral judgments added nothing to those judgments—so far as moral conclusions were concerned, the objectivist was saying the same as the subjectivist but in a louder voice.

Ted Honderich: Professor Ayer, you wrote Language, Truth and Logic when you were only twenty-four, in 1935, and achieved fame by way of it. Tell us a bit about the writing.

A. J. Ayer: After I'd taken my Schools at Oxford—I read Greats—my tutor Gilbert Ryle suggested that I go away for a couple of terms. I had already been appointed Lecturer at Christ Church, and I wanted to go to Cambridge to study under Wittgenstein, but Gilbert said no, don't do that. We've got a lot of people going to Cambridge and we've a vague idea of what Wittgenstein is up to, but I believe something very interesting is happening in Vienna, under Moritz Schlick. Why don't you go to Vienna?

I'd just got married for the first time, and I thought Vienna would be a nice place to go to for a honeymoon. At this point I didn't speak much German, but I thought I'd pick up some, which I did, and so I went and worked with the Vienna Circle. I couldn't really take much part in their debates, but I understood what was going on and came back very enthusiastic about what they were doing. They were extremely empiricist, very anti-metaphysical, anti-religious, and this suited my cast of mind very much. I immediately started lecturing at Oxford on—I think it was Russell, Wittgenstein and Quine. Russell was at that time almost a forbidden subject at Oxford, and Wittgenstein and Quine were people who'd not been heard of.