AYER
(1910 1989)
LOGICAL
POSITIVISM/EMPIRICISM
The son
of a French-Swiss timber merchant and a Dutch Jewish mother, Sir Alfred Ayer
was educated at Eton (where he was a militant atheist), Christ Church, Oxford,
and at the University of Vienna. In
Vienna he attended meetings run by Carnap and other logical positivists. His espousal of this philosophy and his
publication of Language, Truth and Logic in 1936 shook the conservative
establishment at Oxford, to which he had returned as lecturer at Christ Church
three years earlier. After war service
he became Dean of Wadham College, Oxford and in 1946 was appointed Grote
Professor of the Philosophy of Mind and Logic at London University. In 1949 he was back again at Oxford as
Wykeham Professorship of Logic and a Fellow of New College. He was elected
Fellow of the British Academy in 1952 and was knighted in 1970. He was President of the Humanist Association
for six years, and was also an enthusiastic football fan (Tottenham Hotspur).
PHILOSOPHY OF LANGUAGE AND LOGIC
[1] Ayer [Language, Truth and Logic,
ch. IV] distinguished two classes of significant
propositions. (1) Synthetic
propositions, which concern matters of fact, are testable by observation, and
thus are known a posteriori. (2) The formal propositions of logic and mathematics, on the
other hand, which have nothing to say about the world, are said to be analytic
and therefore tautological, in that they are true 'conventionally' by virtue of
the meanings of their constituent symbols, and are thus known a priori. Any propositions which do not
fall into either of these two classes Ayer held to be 'metaphysical' and
non-sensical [a]. Underlying this
position was his commitment to the verification
principle: a proposition is
significant if and only if it is either a tautology or empirically verifiable.
Ayer in fact distinguished between a strong and weak form of the principle. As the strong form that a proposition is
meaningless unless its truth can be conclusively established by observation seems
to rule out universal laws or propositions about the past, he confined himself to the weak
form, which requires only that some observation should be 'relevant' to the
determination of a proposition's truth or falsity [b]. In
his introduction to the second edition of Language,
Truth and Logic, in response to
criticism, he modified his statement of the verification principle still
further. He first of all distinguished between sentences,
statements, and propositions. Sentences
are grammatically significant sets of words or symbols; and all indicative
sentences, whether or not they are literally meaningful, express
statements. Statements which are
literally meaningful he termed 'propositions'. (For the sake of brevity he
applied the principle of verification to statements rather to the sentences
which express them.) He defined a proposition as "a class of
sentences which have the same intensional [N.B. 'intenSional'] significance for anyone who understands them" [ch. V]. He rejected the view that propositions were real entities
or the objects of 'intentional attitudes' [N.B. 'intenTional'] [c] [See also Central Questions of Philosophy, ch. IX]. Recognising the vagueness
of his usage of the term 'relevant' he
proposed a version of the principle expressed in terms of deduction of an
observation-statement in conjunction with certain other premisses, without its
being deducible from them alone. But as this allowed meaning to any indicative statement whatsoever he
reformulated the principle once more, now distinguishing between direct and indirect verifiability. As
to the status of the
principle itself, it was pointed out by critics that it was neither a
tautology nor a deduction from observation-statements. Ayer therefore said that he regarded it (in the weak form)
not as an empirical
hypothesis but as a stipulative definition [LTL, 2nd edn, Introduction]; and that it perhaps should have been interpreted
as providing a means to demarcate
literal sense from nonsense [CQP, II A] [d].
Having, as he thought, eliminated
metaphysics Ayer supposed he could pursue philosophy as an exercise in analysis, in the sense that
its job is to investigate the logical relations and intertranslatability
between various classes and levels of statements (object language,
sense-experience language, scientific statements, 'common sense' ones). Philosophy is therefore now to be understood
properly as a "department of logic" [LTL, ch. II]. Underlying Ayer's general approach,
particularly in his later writings, is the view that philosophy is a quest for justification [e]. He was therefore critical of the methods and
assumptions of 'ordinary language'
philosophy, which he felt is not particularly illuminating or helpful in
dealing with philosophical problems. And while he allowed [The Problem of Knowledge,
ch. II, v] that words must be used in accordance with a set of rules if
they are to be given descriptive meaning, he said it is open to individuals to use rules of their own
without it being essential that they should be capable of being publicly
checked. In principle Ayer therefore allows the possibility of a 'private
language' [f].
KNOWLEDGE
[2] In his account of perception Ayer
initially [Foundations of Empirical
Knowledge and 'Phenomenalism'] promoted a theory of linguistic phenomenalism. He argued
that observation cannot help us to decide between 'realist' and 'sense-datum'
theories. He saw it as a question of
'convenience' whether we adopt the realist view that material objects can possess different
colours at the same time or the sense-datum view that they cannot. It comes down, in the last analysis, to a decision to use a technical
'sense-datum' language, into which sentences about material objects can be
translated, at least in principle [FEK, I] [a]. The sense-datum language, Ayer argues, is best
able to deal with the problem of illusion. He accepted, however, that the latter can never formally specify
material objects precisely, so that we cannot analyse statements about, say, a
table into a set of statements about sense-data. [See Problem
of Knowledge, ch. III, vi.] Nevertheless the attempt to construct assertions about material objects out of empirical data
is still legitimate.
In the Problem
of Knowledge [ch. III, vii] Ayer
also considered the issue of
perceptual knowledge in the context of his examination of justification in the face of sustained assaults by sceptics [ch.
II]. In earlier writings [for example, Language, Truth and Logic, Introd; and
'Basic Propositions'] he
had supposed there to be 'basic propositions' (such as 'This looks to me to be
red') which are 'incorrigible'. He had
already criticized the claims of the 'cogito' [LTL, II; see also PK, II, iii], but he also later came to reject the empiricists'
claim to incorrigibility [PK, II, vi; see also FEK, II, 8] and agreed that the sceptic is
correct in denying that sense-datum statements are either equivalent to or are
a logically conclusive proof for material object statements. However, he says the former can be used for judging the latter
this constitutes 'justification'. Indeed, having knowledge as such was regarded by Ayer as having the
right to be sure about one's belief in the truth of a statement; and it
is a matter of how strict we wish to make the criteria. But the logical possibility of error cannot
be ruled out. And this could occur even
in one's own 'private language' [see 1g], for making mistakes
in assessing one's experience need not be the same as making mistakes in one's
choice of the correct words to describe it. [See PK, chs 2, v; on sense-data see also Metaphysics and Commonsense, 'A Reply to Austin', and CQP, ch. IV A.]
The notion of justification is discussed
further in The Central Questions of Philosophy [ch. VIII C]. Here Ayer says that a belief is justified if it accords with the available
evidence, or is derivable from some wider generalization [b]. However, this raises the
problem whether it is sufficient that the propositions used to justify a belief
are true. This would give us a criterion
for justification, but it does not require us to know that the criterion has
been complied with. Is it therefore
necessary that we should have a good reason to believe that they are true? If so, we run the risk of an infinite
regress. We can stop this only by making
special rulings on the basis that there is evidence of a given strength in its
favour.
In Problem of Knowledge [ch. II, ix] and Central Questions [III E] Ayer identified three
standpoints characterizable by their different responses to the sceptic. (1) The naive realist denies there is a gap to
be bridged between sense-impressions and physical objects: we perceive such
objects directly. (2) The reductionist
(including early Ayer) accepts the sceptic's objections on this point but
argues that statements about physical objects are translatable into statements
about sense-impressions. If the sceptic
opposes this claim, it is open to those who adopt a 'scientific' approach to
argue (3) that the existence of physical
objects is a probable hypothesis which one is justified in accepting because of the way it accounts for our
experience. Even if this claim is
rejected, it can be argued that justification need not be confined to either
deductive or inductive procedures as the sceptic seems to suppose.
Ayer's later theory of
perception [The Origins of
Pragmatism] is based
on a distinction between a realist theory of being, which gives primacy to
physical objects, and an 'empiricist-sensory' theory of knowledge he now
refers to our experiences as 'qualia' [c]. Priority in knowledge is thus no longer
coincident with what is supposed to be prior in being. He argues further that out of the
spatio-temporal relations which are given to us directly in our
sense-experience we can construct a system of physical space and time. The ontological issue now is whether the
realm of physical objects is best understood in terms of naïve, commonsense
'realism' (tables and chairs, and people) or of science (atoms and molecules,
etc) [see 3c].
Ayer's general methodological approach is
also apparent in his treatment of problems of the self, other minds, and memory. Earlier [LTL, Introd. and ch. VII] he had argued for a theory that statements about other
people's minds are translatable or 'constructible' into statements about their
bodies. However this leads to the
problem that we must consistently regard statements about our own minds as
being equivalent to statement about our own bodies. Rejecting this behaviourist analysis Ayer
therefore argues [CQP, ch. VI E; see also 'One's Knowledge
of Other Minds'] that the accounting for the behaviour
of others by analogously attributing
to them conscious thoughts, sensations, emotions, purposes, like those I
directly experience in myself, is a consequence of accepting a "whole body of
theory". One does not have to rely on
inductivism [as he does in The
Problem of Knowledge]. Similarly it is possible that my
memories and therefore statements about the past are mistaken. But notwithstanding the logical possibility
that an occurrence of a memory experience may be logically consistent with the
non-existence of the previous event of which it purports to be a memory, the realistic view that memory
is trustworthy is simpler [d], "besides supplying
the goods in which the other theory [namely, memories of an unreal past]
trades".
METAPHYSICS
[3] Ayer's early logical positivist philosophy was iconoclastic and
explicitly anti-metaphysical in virtue of the verification theory of meaning. However, his later writings [see especially Metaphysics and Common Sense] suggest he
had acquired a more sympathetic attitude. He now regarded metaphysics as an attempt to build a
system which would accommodate contemporary scientific concepts and
principles. Metaphysics was thus seen as
a kind of revisionary and constructive analysis [a], and
as having some explanatory value as a 'secondary system' [CQP, III C] [see below 3c]. In Language,
Truth and Logic he seemed
to be committed to a
'neutral monist' ontology. Central to this was the claim that 'entities' such as physical objects and minds could be
turned into logical constructions (namely, 'sets of experiences) by a process
of reductive analysis and thereby be shown to be 'unreal' [b]. However, he came to adopt
the view that one must choose between one of two supposedly conflicting realist 'systems' the scientific
account of physical objects (in terms of particles, and so on) and the common sense or realist
view that the world consists of tables, trees, and the like. In Central
Questions [ch. VE] he discusses the scientific
theory in terms of primary and a
secondary system. The primary system includes the data (of immediate
perception) and the propositions that support the theory, while the theory as
such belongs to the secondary system (which also includes 'entities' which
cannot be identified with objects of the primary system but which are
conceptual tools for arranging the primary facts). In the case of conflict the one system is treated as concerned with
fact, the other as explanatory. Because the distinction between fact and theory is only relative,
Ayer thinks we have some choice as to
where to draw the line, but says a "reasonable decision" can be made. The question of what actually
exists is an empirical one to be
considered within the framework of the theory which supplies criteria for
answering it [c]. [See also CQP, VII B. and The Origins of Pragmatism.]
On the question of minds, Ayer [CQP, VI B] rejects claims that there are
mental substances or transcendental egos. We have no empirical or other grounds for
asserting the existence of such entities. There is no self
other than inter-relations of experiential data. The claim to self-consciousness, he says, is just the claim that one's present or past
experiences are one's own. Moreover, 'I' and 'my body' are not simply
substitutable. Rather, "my body is
grammatically represented as one of my possessions". However, he allows that grammar is not always
a safe guide to the facts [d]. The use of the personal
pronoun commits us to no more than is strictly necessary for the establishment
of one's self-identity; and experiences suitably related to one's body and to
each other are sufficient or this purpose. Our sensations,
perceptions, and thoughts are indeed mental acts: but for Ayer they do not have
'intentional' objects; rather they
are to be understood as predicable to 'persons' regarded as physical
objects (which, like other physical objects are the "product of
theory"). Thus Ayer does not deny we have an inner private life;
and he rejects 'physicalist', that is, behavioural or dispositional theories as
well as functionalist and identity theories of mind [CQP, VI D;
see also Philosophy in the Twentieth
Century, passim] [e].
METHODOLOGY
[4] The distinction between primary and secondary
systems is employed also in Ayer's analysis of explanation [CQP, VII] and causation [VII
C, VIII D]. He says that the ascription of causality
involves nothing more than a de facto correlation
or constant conjunction of facts, and that this implies reference to a
generalization of a law-like character in that it can be 'projected'
over undetermined or imaginary instances. (He argues for causal
terms to be considered as facts rather than as events, because in this
way they can accommodate 'negative' causes, and they fit in better with the
complexity of usage to cover states of affairs at different observational or
theoretical levels.) Correlations
occur at the primary level while projections take place at the explanatory
secondary level [a]. However, he argues that not all constant conjunctions
are causal: some correlations are
accidental, and many may relate to human decisions and actions, and the
generalizations we are 'disposed' to project need be no more than "generalizations
of tendency". The difference between
accidental generalizations and generalizations of law consists in a difference
in our attitude towards them. Generalizations of fact are more 'vulnerable' to new information in a
way that generalizations of law are not. But the latter entail 'unfulfilled conditionals'. A particular event upon which we base a projection is said to be the cause and a 'necessary' condition only in
the sense that the behaviour would not have occurred without the event (that
is, the corresponding statement is a counterfactual conditional). In general, rejecting the distinction between motives and causes,
Ayer considers the explanatory model of the natural sciences can be extended to
the human sciences [see 'Man as a Subject for Science'] [b]. In universal generalizations, he
suggests, there are various features which lead us to single out one factor
rather than another as the cause (for example, the results of our own actions, the role played by events in a wider explanatory system, and so on). Otherwise identification of such factors is
arbitrary. In the last analysis, cause
and effect have their place only in our imaginative arrangements and extensions
of the facts at the primary level.
Ayer's account of explanation requires
theories to fit the facts, that is, if they are to have any explanatory value
they must be empirically testable. This leads to the problem of induction [CQP, VII A, VIII A] (though he says that simple inductive procedures
achieving universal hypotheses by generalizing from observed instances have
a part to play in comparison with the
advancing of theories by connecting events in novel ways). The assumption that event A will be followed by event B (it having done
so on a previous occasion) presupposes that nature is uniform. However, he argues [Probability and Evidence and CQP, VIII A] that in formulating the principle we must avoid making it either too strong or too weak. If it is made too strong, we force it into a
deductive form (premisses, conclusion) which will be invalidated by any
exception. If it is too weak, it will be
consistent with any sequence of events. It is legitimate, indeed
necessary, to seek for 'backing', but Ayer accepts that the possibility of
error cannot be eliminated [c]. As noted above [see 2b], there is a problem with
attempts to justify our beliefs. There is also a problem with
evidence. Confirmation procedures are beset with paradoxes (such as
Hempel's). Even the falsificationist
approach is inadequate [CQP, VIII C] [d]. It is an inductive step, Ayer says, to assume
that a theory which has passed a variety of testing procedures leading to
increasing degrees of corroboration is a better guide to the future than one
which as not been tested or which has but has been found wanting. Morever, we do require hypotheses to be confirmed. Consider the hypothesis that malaria is
contracted as a result of a mosquito bite. According to the falsificationist we should not be interested in a
person bitten by the insect if we did not know whether he had malaria, because
his case could not falsify the hypothesis. But, according to Ayer, if the experimenter discovered that the subject
had contracted the disease this would be taken as confirmation.
The concepts of backing and testing are
connected with that of probability;
and this is also relevant to Ayer's concern with the assessment of evidence in
the context of his critique of scepticism and his analysis of justification.
[See CQP, VIII, B; also Probability and Evidence.] To explain probability Ayer discusses three
senses of the term used in different kinds of statements, and which he says
must be kept distinct. (1) A priori
statements such as those about, say, the throwing of dice. These relate to the mathematical calculus of
chance and has nothing to say about the likelihood of actual events. (2) Statistical statements, such as that
about the probability that an unborn child will be a boy. These relate to a frequency theory referring
to classes of events, and therefore are not helpful in individual cases, as an
individual may belong simultaneously to different classes and this gives rise
to problems of choice. (3) Statements of 'credibility'. These may be based
on statistics. But Ayer rejects the view
that they can be understood in terms of a logical relation; for (i) they then
become analytic; (ii) the probability may vary according to the evidence. There
can be no grounds for deciding between different statements all of which are
logically true. How then is evidence assessed? Can we be sure it has all been gathered in a given explanatory situation? Is there not an arbitrary element involved? Ayer argues that "'p' is
probable" is to be understood as meaning that it is reasonable to believe 'p'
rather than as a qualified assertion of 'p' [e]. We must therefore appeal
to all relevant factors, negative or positive. But this gives rise to the problem of the reliability of sample
instances. Are they fair or
deviant? Ayer says they must be supposed
to be fair; we can go no further.
Ayer's conclusion from his discussion of paradoxes and probability
that, whatever the evidence, we still have some latitude in our choice of the
hypotheses we are going to project. We can offer different criteria
or standards of rationality, but in the last analysis the only test is whether
the method of choosing hypotheses 'works' whether the past proves to be a
successful guide to the future [f]. And by 'success' he means the likelihood of
our being correct, as measured in terms of the theories we accept.
ETHICS/ AESTHETICS
[5] Ayer's views on ethics were first set
out in Language, Truth and Logic [ch. VI] and generally remained unchanged in later essays [see, for
example, 'On the Analysis of Moral Judgements']. (He notes that what he will say about
statements of ethics applies to statements of aesthetics, and indeed to all
'judgements of value'.) He starts by
dividing ethical statements into four classes: (1) propositions which express
definitions of ethical terms or judgements about such definitions; (2)
propositions which describe phenomena of ordinary experience; (3) "exhortations
to moral virtue"; and (4) actual ethical judgements. He then confines his discussion to the first
class, which he says are the only propositions properly belonging to ethical
philosophy. (The others are either propositions
of psychology or sociology or are not really propositions at all.) Ayer denies that 'normative' sentences (for example, 'x is wrong') are
equivalent to sentences expressing any kind of empirical propositions and so he
rejects two kinds of naturalistic moral philosophy subjectivism and
utilitarianism [a]. According to one version of the former, to
call an action right, or a thing good, is to say that it is generally
approved. But Ayer argues that no
self-contradiction is involved in saying that some generally approved of action
is not right, or a thing not approved of is good. Similarly, in the case of utilitarianism,
there is no self-contradiction involved in asserting that it is sometimes wrong
to perform the action which would actually or probably cause the greatest
happiness. He also rejects 'intuitionist' or absolutist' theories,
as they provide no criterion for determining the validity of moral
judgements. Although according to such
theories moral judgements are held to be synthetic, they are also regarded as
not empirically verifiable. However, Ayer agrees with the absolutists that fundamental ethical concepts
(good, duty, obligation) are unanalysable. However, he regards them as 'pseudo' concepts [b], in that they add nothing to the factual
content of statements such as 'You stole the money' in 'You were wrong to steal
the money'. His own position is that ethical and aesthetic statements have no objective validity. Ethical
and aesthetic concepts not only serve to express feeling; they also an emotive function, namely, to
arouse feelings, for example, of moral disapproval, so as to stimulate action. And some are used in such a way as to give the sentences in which
they are used the effect of commands [c]. In cases of dispute, argument is not about
values but about questions of fact whether, for example, a person has
misjudged the consequences of an action, or the motivation of the agent, and so
on.
CRITICAL SUMMARY
Although in the course of
his long career Ayer moved some way from the youthful radicalism of Language, Truth and Logic, he remained
firmly committed to the basic assumptions of empiricism. Philosophy is regarded
as essentially the "logic of science" the analysis of interrelations and
translatability between different classes and levels of statements. However,
the modifications he introduced are significant. He came to be less concerned to eliminate metaphysics than to investigate how
knowledge claims might be justified in the face of scepticism; and this led him
to examine the concepts of evidence and probability. His broadly pragmatic
approach and appeal to 'reasonableness' allowed it to be a matter of choice how
strong one's criteria for knowledge should be. His linguistic phenomenalism gave way to a more physicalist approach
later grounded in his distinction between primary (factual) and secondary
(explanatory) systems. Persons too are
physical objects, the 'self' being understood in terms of interrelated
experiential data. He preserved the
privacy of 'inner' life against behaviourism and dispositional theories but
also rejected Cartesian or transcendental accounts. Generally the question of what there is is a
matter to be determined by criteria appropriate to the theoretical framework
within which one is by choice operating.
Perhaps the main objection to Ayer's
general approach comes from linguistic philosophers. They criticize his ready
acceptance that our conceptual scheme may be modified as utility requires
without any recognition of the alleged primacy of our everyday publicly
validated discourse, and also his conviction that any change has to be effected
in conjunction with our scientific theories. The distinction he made between primary and secondary systems, and
within which he accommodated his account
of physical objects and minds, is thus rejected. It has also been claimed that Ayer is too
firmly wedded to the distinction between logical and factual statements. Recent work has raised questions about the
supposed a priori-analytic-necessary
and a
posteriori-synthetic-contingent parallelism. And although he had been receptive to Quine's
ontology, Ayer never responded to his critique of the analytic-synthetic
distinction itself. His ethical theory
has also elicited considerable critical response. It has been said that while ethical
statements do have an evaluative function they also have both prescriptive and
descriptive functions. Even if this
alternative account is equally contentious, most philosophers would accept, as
against Ayer, that ethical statements are more than just expressions of
feelings. Moral terms have 'meaning'
(however this may be construed). It is
also questionable whether the notion of a moral dispute can have purchase given
Ayer's premisses. Is the dispute just
about, say, misunderstanding or motives, or about consequences?
Ayer: [of many writings] Language, Truth and Knowledge (1936; 2nd revised edn 1946); The Foundations of Empirical Knowledge (1940); Philosophical Essays (1954) includes 'Phenomenalism'
(1947-8), 'On the Analysis of Moral
Judgements' (1949) 'Basic Propositions' (1950), and 'One's Knowledge of Other
Minds' (1953); The Problem of Knowledge (1956); The Concept of a Person and Other Essays (1963); Metaphysics
and Common Sense (1969) includes 'Man as a Subject for
Science' (1964) and 'Has Austin Refuted the Sense-data Theory?' (1967); Probability and Evidence (1972), and The Central Questions of Philosophy (1973).
Studies
J.
Foster, A.J. Ayer.
O. Hanfling, Ayer.
Collections
of essays
T.
Honderich, T., Essays on A.J. Ayer.
L. E.
Hahn (ed.), The Philosophy of A. J Ayer.
CONNECTIONS
Ayer