[lit-ideas] Re: Ayer Nay Sayer

  • From: Jlsperanza@xxxxxxx
  • To: lit-ideas@xxxxxxxxxxxxx
  • Date: Wed, 30 May 2012 21:03:17 -0400 (EDT)

In a message dated 5/30/2012 7:10:42  P.M. UTC-02, 
donalmcevoyuk@xxxxxxxxxxx writes:

Walter recently made a  remark that was very complimentary to A.J. Ayer, to 
which I suggested a useful  antidote in Popper’s reply to Ayer’s paper for 
P’s Schilpp volumes. [We might  also mention as an antidote Ayer’s 
misrepresentation of P’s position elsewhere,  beginning with Language, Truth 

Ayer’s paper and P’s reply  might be taken as a useful example of the kind 
of divide that opens up between  those who think on ‘justificationist’ 
lines and those who profess not to.   The typical criticisms of P’s theory of 
knowledge – especially his account of  scientific knowledge – are ‘
justificationist’; and the typical Popperian  rebuttals are 
These typical criticisms involve alleging  that either (a) (despite 
protestations to the contrary) P’s position is only  viable given certain ‘
justificationist’ assumptions [which P is alleged to  smuggle in, for example, 
in the 
guise of his account of how one theory might be  rationally preferable to 
another because of its greater verisimilitude or its  being better 
corroborated]; or (b) without any justificationist underpinning,  P’s theory of 
knowledge collapses into an outright scepticism [where, for  example, no theory 
can be preferred to another on rational grounds]. The  rebuttals seek to show 
that P’s position of ‘critical rationalism’ is viable  without 
justificationist assumptions or underpinnings, and so both (a) and (b)  are 

In evaluating these disputes, it is interesting to consider  that there may 
be a kind of ‘paradigm-shift’ involved in switching from a  
justificationist to a non-justificationist theory of knowledge:- the hardened  ‘
justificationist’ cannot accept the viability of a non-justificationist  
approach and 
seeks to show that any supposed ‘non-justificationism’ either is a  ‘
disguised justificationism’ [in which case only, it may be viable] or is not  
viable [because it lacks the necessary element of justification]. In other  
words, the ‘justificationist’ cannot accept the idea that all knowledge lacks  
justification and is merely guesswork and yet some guesses may critically 
and  rationally be preferable to others. The justificationist cannot accept 
that all  knowledge is fallible – i.e. that any ‘knowledge-claim’ may be 
mistaken – even  if this fallibilism does not imply that all knowledge is 
mistaken. In fact,  where knowledge is taken in the typically 
sense to mean  ‘justified true belief’, it would seem that by definition ‘
knowledge’ cannot be  either mistaken or without justification. Whereas the 
identification of  knowledge with JTB is, for P, simply another subjectivist 
and justificationist  blunder in the western tradition of thinking about 

Popper’s  reply, to “Sir Alfred Ayer’s contribution”, extends over pages 
1100-1114 and is  divided into five sections. 

The first section, on Verisimilitude, rebuts  Ayer’s critical question – “
In what way, then, does the concept of  verisimilitude afford us a criterion 
for assessing our progress towards truth?”  – by explaining that P never 
offered this concept “as a ‘criterion’ of  anything.” Verisimilitude is not 
a criterion of progress towards truth for “to  say that a theory has a 
greater verisimilitude than one of its competitors  remains essentially a 
of guesswork.” 

Here Ayer’s treating  verisimilitude as “a criterion” of “progress 
towards truth” is to give it a  ‘justificationist’ role: a role so that we 
be justified in preferring one  theory over another because its greater 
verisimilitude is guaranteed by some  defined measure and its greater 
verisimilitude thereby guarantees progress  towards truth. In P’s philosophy ‘
verisimilitude’ is not guaranteed or justified  [being “essentially a matter of 
guesswork”] nor does it guarantee progress  towards truth [whether a more ‘
truth-like’-seeming theory takes us closer or  further away from ‘the truth’ 
is also a matter of guesswork]. In order to  appreciate these respective 
positions, we might argue out particular cases – to  see, for example, whether 
verisimilitude might plausibly be deployed in a  rational and critical way 
but without its being underpinned by any  justificationist guarantees. 

Some forty years ago, P’s own proposed  definition of verisimilitude was 
proved defective [by Tichy and, independently,  Miller], though this did not 
mean the concept was proven irremediably flawed.  Subsequent search for a 
tenable definition has led to developments that  logically refine what is at 
stake but no entirely satisfactory definition has  been found as yet. Nor 
perhaps is it settled what follows from this or what  follows if one is not 
found (despite the Wittgensteinian author of the Stanford  Entry on Popper 
wanting to suggest the defects of P's definition shipwreck P's  theory of 
knowledge). The search for a satisfactory account of ‘verisimilitude’  has 
a highly technical area beyond the reach of most non-specialists. The  
implications of this ongoing work is also beyond the reach of  most.

The second section discusses Tarski’s theory of truth. Here P  mentions “
that Tarski’s conception of a metatheory was for me important for a  
different reason.
“In the discussions following some  of my early lectures to the fringe of 
the Vienna Circle I had been heckled by  some Wittgensteinians for speaking 
of “methodological rules”: they indicated  that, according to Wittgenstein, 
this must be nonsense, since such rules could  not be truth functions of “
elementary” (or “atomic”) propositions. Obviously  they were not Carnapian “
syntactic” rules either. I had never accepted these  prohibitions, which 
appeared to me arbitrary and even high-handed. Nevertheless  I was not really 
happy about how to explain what I was doing until I learned  from Tarski that 
we need even in logic a metatheory or metascience not confined  to ‘logical 
syntax’.” (It is the Wittgenstein of the Tractatus and not  Investigations 
that is the source of the heckling.)

The third concerns  The Verification of Theories. What P says here resists 
paraphrase so that a  considerable part of that section is set out below:
“Almost all philosophers  since Kant agree with him that there can be no 
criterion of truth…and with the  help of Tarski’s theory of truth it is even 
possible to prove that, for any but  the most trivial languages, there can 
be no general criterion of truth, even of  logical truth, to say nothing of 
empirical truth.
“By a  criterion of truth is meant a kind of decision method: a method that 
leads  either generally, or at least in a certain class of cases, through a 
finite  sequence of steps (for example, of tests) to the decision whether 
or not the  statement in question is true. Thus in the absence of a general 
criterion of  truth it may easily happen that we possess true theories, and 
yet are unable to  show, to our satisfaction, that they are true. What can 
also happen is that we  are able to establish some statements as true, by a 
sort of lucky coincidence  rather than an application of a criterion of truth 
(which may not exist in the  case in question).
“Thus to assert that we have a general  criterion of truth is to assert 
very much more than to assert that certain  statements are true.
“Now [to] the two crucial  paragraphs of Ayer’s paper, as far as the 
verification of theories is  concerned…
“ ‘First, however,’ Ayer writes…,  ‘I want to examine his [Popper’s] 
claim that, at any rate so far as empirical  propositions are concerned, there 
is no general criteria by which we can  recognize truth.’ Thus it is my 
claim which is being examined here, and the term  ‘criterion of truth’ is 
clearly used in the sense explained here – a general  criterion by which we can 
recognize truth.
“Yet…Ayer reaches…a conclusion which is the precise opposite of  mine:
‘Accordingly, if we can lay down a general criterion for recognizing  the 
truth of basic statements [test statements], there is a sense in which we  
shall after all have a general criterion for recognizing empirical  truth.’
“By ‘empirical truth’ Ayer means,  especially, the truth of scientific 
theories; and the statement just quoted  implies that, given an empirical 
method to decide on the truth or falsity of  what I in Logik der Forschung 
‘basic statements’ (and now prefer to call  ‘test statements’), we can 
decide the truth or falsity of scientific  theories.
“It may be said that Ayer does not  and cannot mean this, because…he 
himself repeats most of the arguments by which  I support my thesis of the 
one-sided refutability of universal theories.  However, the last three 
of the second paragraph are clearly designed  to arrive at the conclusion 
they do arrive at, by an apparently smooth-running  but quite invalid argument, 
leading off with a word – the word ‘Nevertheless’ –  that succeeds in 
invalidating all the preceding  admissions.
“Ayer’s argument is, in  brief:
Step (1) Admission: ‘Finding a counterexample  proves the statement false, 
but failing to find one does not prove it  true….’
Step (2) ‘Nevertheless…the absence of any  counterexample…is….a necessary 
and sufficient condition of truth….’ [This step  is invalid, as I shall 
show, and it invalidates the argument; but even if we  grant it, the argument 
does not become valid.]
Step (3)  ‘…the only way in which any empirical statement can meet with a 
counterexample  is by its coming into conflict with a basic statement [test 
statement]…[; thus]  the truth or falsity of any empirical statement…is 
entirely determined by the  truth or falsity of some set of basic statements.’ 
(Italics mine.)  
Step (4) consists of the last statement of Ayer’s second  paragraph, ending 
triumphantly, as quoted above, ‘…we shall after all have a  general 
criterion for recognizing empirical truth’.
“Is  the argument valid, provided we admit step (2), as for the moment I am 
prepared  to do? If it sounds so, it is because Ayer is a trifle indistinct 
about what set  of basic statements is ‘some set of basic statements’. For 
the set of basic  statements actually necessary to ‘determine’ the truth 
of a theory A would be  the infinite set of all test statements which could 
be relevant to A, reporting  on all possible tests undertaken anywhere in the 
universe, in the past, present,  or future.
“This is obvious; for by Ayer’s own  admission (see step (1) above), “
failing to find [a counterexample]…does not  prove… [the theory] true’, because 
there may be unrecorded counterexamples. Thus  only if that questionable 
set of basic statements includes complete reports  about all possible 
counterexamples could the set ‘determine’ the truth of the  theory A (always 
provided we grant step (2), which will be discussed later),  while one 
counterexample, one test statement, could determine the falsity of  A.
“But if this set of basic statements is infinite  – one might even say ‘
indefinite’ – it is clear that we would need more than ‘a  general criterion 
for recognizing the truth of basic statements’ in order to  obtain a ‘
general criterion for recognizing empirical truth’; in just the same  way, and 
for just the same reason, that we need more than a ‘criterion’ for  
recognizing the whiteness of swans in order to determine whether all swans are  
white. (This error is perhaps the gravest defect of Ayer’s whole argument.) To  
recognize’ the truth of all the basic statements belonging to the set is  
clearly not an empirical process: it would involve a kind of omniscience – an 
 omniscience with respect to basic statements.
“Thus  Ayer’s argument establishes at best merely the thesis: ‘basic 
omniscience’ (as I  will call it) is involved in any ‘general criterion for 
recognizing empirical  truth’: or empirical omniscience involves basic  
“This thesis sums up, I suggest,  all there is in this part of Ayer’s 
criticism. It hardly needs saying that even  if it were validly argued, it 
not reveal any weakness in my  views.
“But even this somewhat  unexciting thesis is invalid, owing to the 
invalidity of Ayer’s step (2). I will  discuss this step briefly, although it 
somewhat subtle, and although its  invalidity need not be established in order 
to show that Ayer’s conclusion – his  step (4) – is mistaken, and that 
there is no ‘general criterion for recognizing  empirical truth’. 
“Ayer contends that  ‘the absence of any counterexample is a necessary and 
sufficient condition of  truth’. This view may be defended for theories 
like ‘All swans are white’: if  there exists (existed, will exist) no 
counterexample, that is, no non-white  swan, then indeed the theory is true. 
But the 
view is untenable for all more  abstract theories, such as Newton’s. 
Non-white swans are observable; Newton’s  forces varying inversely with the 
of the distance are not. (This is why  Berkeley said that Newton’s forces 
were ‘occult’.) The idea that two theories  which agree with respect to all 
testable consequences must be equivalent, is  mistaken. Einstein’s special 
theory of relativity and Lorentz’s interpretation  of it are two theories 
which contradict each other (Lorentz suggested the  existence of an inertial 
system that is absolutely at rest). It does not help  here to say that Lorentz’
s interpretation contains a metaphysical element that  has to be omitted. 
Einstein’s denial is just as metaphysical, or almost as  metaphysical, 
because nothing observable follows from it. (It is not, in  general, possible 
split a theory into an empirical and a non-empirical part  so that the ‘
empirical part’ constitutes a system which can be characterized by  a finite 
number of empirical hypotheses; on the contrary, Craig’s theorem can be  used 
show that the empirical part of a theoretical system will not in general  
by finitely axiomatizable. This, obviously, holds even for a comparatively  
simple theory such as Newton’s theory of gravity.)
“Thus there may be two theories which are incompatible, but have identical  
observable consequences; and one of them may even be empirically better 
than the  other as it may suggest a further generalization (such as General 
Relativity)  which has new and interesting empirical  consequences.
“But if A and B are  incompatible, they cannot both be true, even if there 
is no counterexample to  either of them; and this means that Ayer’s 
suggestion (2), that the absence of  counterexamples is a sufficient condition 
the truth of a theory is  mistaken.”

In other words absence of a counterexample is a necessary but  not 
(necessarily) sufficient condition of the truth of a theory. 

“So  Ayer’s deceptively smooth-running argument….contains at least two 
steps each of  which alone invalidates it.”

The position may be somewhat more involved  than might be gleaned from P’s 
account here – which strives to avoid needless  complication. For example, ‘
All swans are white’ only “may” be a case where the  absence of any 
counterexample is a sufficient condition of truth. Here it may  depend on 
the universal generalization [‘UG’] ‘All swans are white’ is  taken to 
express a merely contingently true UG or one that is true because there  is a 
law-like connection between swan-ness and whiteness such that the UG holds  
as a universal law of nature [‘UL’]. Consider a merely contingently true UG 
like  ‘All dodos die within x years’ where there is no counterexample yet 
there is no  law of nature that would forbid a dodo ever living beyond x 
years – here the  absence of a counterexample would not be a sufficient 
condition of the truth of  the UG as a UL, even if as a merely contingently 
true UG 
it would be true by  virtue of the contingent fact that there is no 
counterexample. Where ‘All swans  are white’ denotes a UL [and not merely a UG 
might be merely contingently  true] it denotes there being an abstract or 
unobservable property of the  universe such that it is a structural property 
of the universe that a non-white  swan is an impossible structure (not 
logically impossible but perhaps physically  or chemically or biologically 
impossible). Taken as a UL, the absence of a  counterexample is not a 
but only a necessary condition of the truth  of ‘All swans are white’. But 
none of this rescues Ayer’s views from P’s logical  demolition.

The next section concerns The Verification of Basic  Statements. P’s has 
defended the view that the acceptance of a basic statement  is never logically 
forced on us [as they cannot be verified] and so their  acceptance involves 
a decision, but that decision may be critically arrived at  and need not be 
arbitrary [acceptance may, for example, be due to the basic  statement 
being part of a reproducible and thus testable effect]. Yet for a  
justificationist this seems unacceptable: if there is no logical justification  
accepting a basic statement, by way of empirical verification, then the  
must be arbitrary – and this indeed turns out to be Ayer’s criticism  (the 
same criticism was proclaimed in Stephen Thornton’s Stanford Entry on  
Popper). For justificationists there is no viable way to critically arrive at a 
decision to accept certain ‘basic statements’ absent justification of 
their  acceptance by way of their verification. Yet there is scant reason to 
accept  this justificationist stance: and P points to the example of a jury 
which may  arrive at a decision after careful critical examination of all kinds 
of evidence  – their decision can never be derived as a matter of logic 
from the evidence,  yet it may be far from arbitrary given the evidence. P 
concludes, “And the  acceptance or rejection of [basic statements] is a matter 
for something like the  scientific jury – the scientific community (which may 
or may not come to an  agreement).”

There is a final section on Subjective Experience and  Linguistic 
Formulation, where P addresses “What is the fundamental difference  between 
Ayer and 
myself?”; but we may be spared this story. (For  now.)


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