A universal adoption of Ayer's principle of verification (A. J. Ayer, Language, Truth and Logic, 1971) as a necessary and sufficient qualifier of statements, renders those areas of human thought that, as theology, do not rely on an empirical or analytic evidence, isolated from the, often mistaken as “superior”, mathematics and science. Theology in particular ends up neglected together with occult, emotions or even insanity. While the challenge of inferiority - “lesser value” - of the “unintelligible” metaphysical statements can be easily refuted on the grounds of positivism itself being incapable of dealing with the necessarily metaphysical concept of a “value”, any attempt at placing the concept of God at the same plane as emotions cannot be left unanswered by a theist.
Introduction of the principle of verification may be seen as an extension of Ayer's earlier work on the classical account of knowledge. Having interpreted the “justified true belief” definition as “the right to be sure” in the article of that title in The Problem of Knowledge, 1956, Ayer has committed himself to the justification criteria, and was immediately faced with the problem of a measure of adequacy.
The principle of verification is a solution to the above problem, which, in Knowledge as having the right to be sure has been expressed in the statement “Words like ‘intuition’ and ‘telepathy’ are brought in just to disguise the fact that no explanation has been found.”
In that light, the principle of verification is an intellectually appealing, practical solution not just to the problem of finding a justification for a knowledge claim, but more importantly to the question of rationality itself. It complements the concept of knowledge, or, indeed, any statement, with a universal verification metric. From this perspective, its value lies not in the absolute correctness of the principle, but rather in the regularity of the aesthetically pleasing consequences.
The principle of verification can also be viewed as a reaction to the “hopelessness” of the search for a conclusive proof of God's existence (or otherwise) and an objective verification criteria for rationality. If indeed the truth of every statement - and thus every knowledge claim as well - is either analytic or synthetic, with no third alternative available, then a claim of a theist, necessarily made about concepts with no horizontal, and only weak vertical relationship to the physical empirically verifiable reality, cannot possibly be assigned a true or false value.
The practical rationality of Ayer's principle of verification has a serious drawback of narrowing the concept of knowledge beyond the minimum acceptable to most people. The favourite argument against it are the consequences of the application of the principle to itself. For, the principle of verification, being obviously non-analytic, cannot be empirically verified by means other than those used to verify any hypothesis, that is by verifying the consequences, ie. its truth implies that “it would be possible to deduce from it the other empirical hypotheses, certain experimental propositions which were not deducible from those other hypotheses alone” (A. J. Ayer, Language, Truth and Logic). The above quotation, aimed at showing irrationality of a belief in God, serves with a much more immediate strength against the principle of verification itself. Because, in Ayer's frame of reference, all knowledge must go through the empirical verification sieve, it is impossible to empirically demonstrate the truth of the principle of verification in the system in which that principle is the single basic axiom. In other words, we cannot, by definition, find a suitable reference proposition as required by Ayer, for any such proposition must necessarily be verified and thus derived from the principle of verification. Therefore, the principle of verification needs to be taken a priori, an approach rejected earlier with reference to all non-analytic statements.
The above self-contradiction argument can in fact be applied to any philosophy which fails to provide an invariant such as platonic realm of pure forms or chaos in Darwin's Theory of Evolution as used in Nietzsche's perspectivism. The basic problem with the argument is that it presumes an internal frame of reference, which, accidentally, is central to the analytic logic and often taken as its definition, namely that all non-true statements are false.
A much more aesthetically appealing argument against Ayer's principle of verification may be constructed by noting that positivism has not only rejected metaphysics, but has been constructed from denial of its implications. The principle of verifications has not been formulated as an objective foundation principle which could sincerely be thought applicable equally to the analytic science and metaphysics, as it has been borrowed from the scientific community which has been employing it for a considerable time irrespective of any humanity, while a truly objective approach would be to search for a basic unbiased principle. Instead, an a priori assumption of the superiority of science has been made, and the resulting hypothesis immediately applied to the different discipline - theology - to which it could equally well be assumed inapplicable, in order to demonstrate its irrationality. The problem raised may be formed into a rather rhetorical question of relevance - should a theory built on denial of metaphysics be allowed to serve as an argument against it?
That process of rejecting an established axiom has been successfully employed in mathematics. However, one cannot reverse-apply the resulting new system to the just-rejected one. In the same way as the theory of relativity cannot be applied to “disprove” Newton's classical mechanics, so the principle of verification cannot be applied to metaphysics. In addition, in the latter case, the rejection of axioms has lead us to a narrower concept of knowledge, a fact that, at least in mathematics, would be immediately taken as a suggestion of a faulty hypothesis. Therefore, while it might not be possible to assign Ayer's concept of truth or falsity to a theist's claim, it must be remembered that Ayer deals with a different concept of truth altogether, a concept which is merely a subset of that recognized by a theist.
The final challenge to the principle of verification, formulated as “a statement is meaningful iff it is true (or false) a priori or is empirically verifiable”, that I would like to raise is the rationale for the special treatment received by the analytic statements, which alone of all non-empirical “expressions” are allowed to be “meaningful”. For an analytic statement, from a simple “a black cat is black” to Fermat's Last Theorem, have but an aesthetic meaning until applied to an empirical hypothesis, thus testing the underlying set of axioms. It might be difficult to argue statements, the truth of which can be derived from the basic principles of logic, which is after all the lower common denominator of philosophy, but, to quote Nietzsche from Beyond Good and Evil (§16), one could face an analytic statement with “Sir, it is improbable that you are not mistaken, but why insist on the truth?”.
If the principle of verification does not reduce the value, the meaning, or any other conceptual, non-empirical quantity - expression - assigned to a statement, it seems that the only correct approach to it is as a categorizing principle, placing the various areas of human thought and experience into discrete sets, particularly suitable for the practically valuable realm of science. In this form, it is no more of a dilema for a theist, positivist or indeed any other philosopher, than the arbitrary assignment of gender to the person of God. It is an expression of the practical difference between theology and science. When the principle of verification is applied to discard metaphysics and theology as “meaningless”, the logical inconsistencies of the principle can be exploited to demonstrate necessity of inclusion of a non-analytic a priori knowledge in any philosophy with a completeness claim.
Patryk Zadarnowski, Sydney 1997