Not many men can claim to be a philosophy professor and a former MI6 operative. Alfred Jules Ayer, a former special operations executive and MI6 agent during World War II, was a man of many talents. From 1933 to 1940, Ayer lectured on philosophy at Christ Church, Oxford. “Freddie,” as he was known by his friends, was also closely associated with the British humanist movement. Influenced significantly by David Hume, Ayer accepted the traditional empiricist view that labeled all genuine propositions as either analytic or empirically verifiable. Like all empiricists, Ayer denied the rational claim that a priori knowledge of the world is possible. He wrote Language, Truth, and Logic when he was only twenty-four years old. In it he advocated the major theses of Logical Positivism, the idea that the only rationally justifiable assertions are those that can be scientifically verified, and those by logical analysis. The work established Ayer as the movement’s leading representative in Britain. The line of empiricism from Locke to Hume had passed to men like Bertrand Russell and Alfred Jules Ayer. Amongst British philosophers of the twentieth century he has been ranked second only to Russell. Although having studied in Oxford, it was in Vienna that Ayer absorbed the basic tenets of Logical Positivism under the leaders of the “Vienna Circle.”
Language, Truth, and Logic (1936) carried some of the ideas of the Vienna Circle and the logical empiricists to the attention of the English-speaking world. Espoused in the work is the “verification principle.” This tenet holds that, unless logical or empirical verification is possible, statements like “God exists” are not true or untrue but meaningless. (In later years Ayer reiterated that he did not believe in God and began to refer to himself as an atheist) With this verification principle, Ayer and the logical positivists take empiricism to the semantic level by focusing on meaning rather than knowledge. Therefore, in order to be meaningful, a proposition that is not analytic must be empirically verifiable.
Language, Truth, and Logic begins with a linguistic indictment upon metaphysics: “Our charge against the metaphysician is not that he attempts to employ the understanding in a field where it cannot profitably venture, but that he produces sentences which fail to conform to the conditions under which alone a sentence can be literally significant.” (35) Hence Ayer uses a “criterion of verifiability” to test the genuineness of apparent statements of fact. Contrary to Karl Popper, Ayer suggests that a sentence should be allowed to be factually significant only if it expresses something definitely confutable by experience. While Ayer admits that our senses can deceive us, he insists that our senses substantiate or confute the judgments based on sensations. Therefore philosophy as a whole must be distinguished from metaphysics. Specifically, Ayer is skeptical of any brand of philosophy that operates deductively from first principles at the expense of scientific induction. For this reason, he takes exception with Descartes’ deductive “cogito ergo sum” premise. Ever the empiricist, Ayer notes, “As Hume conclusively showed, no one event intrinsically points to any other.” (47) Thus a philosopher cannot solve the problem of induction simply by looking to the uniformity of nature. While it is not irrational to expect future behavior, there is in fact no guarantee of future experience. Ayer suggests that we abandon the term “philosophy” as a name for a distinctive branch of knowledge. Instead, he defines “philosophy as a department of logic.” (57) Moreover, he replaces the Berkeleyan and Lockean concept of an “idea” with the term “sense-content.”
Since propositions of philosophy are “not factual, but linguistic in character,” it is Ayer’s task to “dispel those confusions which arise from our imperfect understanding of certain types of sentence in our language.” (57, 62) For example, “what is the nature of a material thing?” is a linguistic question and demands an answer. According to Ayer, it is essentially a problem of the “reduction” of material things to sense-contents and can be answered by indicating the relation between two sense-contents in the same material thing. Ayer describes his system as “a form of empiricism,” insisting that philosophers must not concede to rationalism or the notion that any proposition subject to the test of experience is ever logically certain. (71) Contrary to the famous utilitarian John Stuart Mill, however, Ayer insists that logic and mathematical questions are not determined in the same way as empirical hypotheses. For example, if 5 x 2 ≠ 10, then one must conclude empirical error, not evidence of mathematical fallibility. Therefore one cannot abandon the principles of logic and math without “sinning against the laws which govern the use of language.” (76) Critiquing Immanuel Kant, Ayer defines a proposition as analytic when its validity depends solely on the definitions of the symbols it contains. So analytic propositions can, in a sense, give us new knowledge, but Ayer also insists that they do not increase our knowledge.
Ayer’s empirical propositions are not about absolute veracity, but about probability. Science, as a description of our experience, is at best a means to predict the future. In this way Ayer proves himself the student of Hume: “There is no absolute standard of rationality…we trust the method of contemporary science because they have been successful in practice.” (100) Therefore the Kantian concept of synthetic a priori knowledge is rejected in favor of the idea that all synthetic propositions are instead empirical hypotheses. In the realm of ethics, Ayer stands against both the “absolutist” and “naturalistic” theory of ethics. “That is, we reject utilitarianism and subjectivism, not as proposals to replace our existing ethical notions by new ones, but as analyses of our existing ethical notions…in our language, sentences which contain normative ethical symbols are not equivalent to sentences which express psychological propositions, or indeed empirical propositions of any kind.” (105) According to Ayer, ethics, as a branch of knowledge, is nothing more than a subset of psychology and sociology. Therefore, “it follows, as in ethics, that there is no sense in attributing objective validity to aesthetic judgments.” (113)
For Ayer, “no synthetic propositions are logically sacrosanct.” (121) All empirical observations are open to scrutiny. And this is why Ayer aligns himself with George Berkeley in advocating a phenomenalist approach to the material world. However, contrary to Berkeley, Ayer also contends for a phenomenalist approach to the self: “we have solved Hume’s problem by defining personal identity in terms of bodily identity, and bodily identity is to be defined in terms of the resemblance and continuity of sense-contents.” (127) In Ayer’s thoroughgoing phenomenalism, the self is reducible to sense-experiences – so much that the author even admits the remote possibility of solipsism! Adhering to Logical Positivism (rejection of metaphysics and acceptance of the use of a priori knowledge in logic and math), Ayer concedes the use of deduction in science while admitting “a thing is to be defined, not as a collection of sense-contents, but as logical construction out of them.” (142) It is the relationality of these sense-contents that sets Ayer’s thesis apart. In the end, Ayer emphasizes the unity of philosophy and science. For the sake of factual accuracy in our sentences, Language, Truth, and Logic takes empiricism to the semantic level.
As an empiricist, Ayer is naturally averse to metaphysics. And the beginning of Language, Truth, and Logic makes this explicit. However, as a logical positivist, Ayer is not completely opposed to “reason”. In fact, his brand of empiricism acknowledges the importance of the relations between “sense-contents.” That relationality is constituted in logic and math – two very unexperiential things. And in this way Ayer sets himself apart from his empiricist forbears. While Ayer takes Hume’s empirical principles and applies it to language, he does so by rejecting Hume’s definitions of causes. Hume, like Ayer, believed that the relation between cause and effect was not logical in character. (Hume explained this with his famous billiards example) Therefore he denied the “laws of nature” because they could not be observed. However, Ayer endorsed the “apodeictic certainty of logic and mathematics.” (85) This means that these two fields demanded a priori necessity. It is Ayer’s objective to introduce symbolic devices that enable us to express these highly complex “tautologies” in simple form: “For we show that the truths of pure reason, the propositions which we know to be valid independently of all experience, are so only in virtue of their lack of factual content. To say that a proposition is true a priori is to say that it is a tautology. And tautologies, though they may serve to guide us in our empirical search for knowledge, do not in themselves contain any information about any matter of fact.” (87) Herein lies Ayer’s attempt to wed logic and empiricism in the same language. The British philosopher does not consider a tautology to be “fact” per se. But neither is a tautology “untrue.” Therefore it is permissible in language.
While Ayer is to be commended for his conciliatory attempt to wed logic and empiricism in semantics, his atheism is also evident in several statements regarding religion. For example, he states, “science tends to destroy the feeling of awe with which men regard an alien world, by making them believe that they can understand and anticipate the course of natural phenomena, and even to some extent control it.” (117) Statements like these reveal not only Ayer’s atheism but his view of science itself. For a Humean empiricist, the telos of science is not the study of nature and its dynamics, but rather to predict future behavior as accurately as possible. Therefore, Ayer views science in probabilistic terms. In this sense, we can view his worldview as empiricist, viewing the progression of mankind in terms of prediction and expectation. However, Humean science is not necessarily Newtonian or Einsteinian science. When the “laws of nature” are actually accepted, one’s awe for intelligent design is actually increased! How do we explain gravity? What and where is dark matter? These are the types of things that an empiricist would interpret differently through a prediction lens. In fact, many of these types of questions would be considered irrelevant to someone whose ultimate goal for science is mere prediction of future behavior. Ayer neglects to see the “eternal power” and “divine nature” of God, even in clear scientific discovery! (Romans 1:20) The former MI6 agent is also guilty of tacitly relegating all of religious experience to mysticism: “For we know that if he really had acquired any information, he would be able to express it. He would be able to indicate in some way or other how the genuineness of his discovery might be empirically determined. The fact that he cannot reveal what he ‘knows,’ or even himself devise an empirical test to validate his ‘knowledge,’ shows that his state of mystical intuition is not a genuinely cognitive state.” (119) Does the lack of “empirical” evidence of Christianity consign it to mysticism? And what are we to make of the earliest biblical manuscripts? Do they pass the litmus test of “sufficient” evidence? As the Scriptures likely fall outside of Ayer’s definition of logic, mathematics, or scientific experience, they are no doubt disqualified. Nevertheless, Alfred Jules Ayer rightly combats rational dogmatism in its lack of empirical evidence and accepts a noble task in seeking to establish factual language. Despite his approval of logic, his aversion to induction is enough to discount God’s existence as well as a natural order that attests to God’s intricate and glorious design.