The Alleged Impossibility of Metaphysics: A Refutation of A. J. Ayer

Brook Johnson
9 min readOct 27, 2020
Photo by Efe Kurnaz

In A. J. Ayer’s “Demonstration of the Impossibility of Metaphysics,” he argues that all metaphysical questions and propositions about the nature of reality are in fact pseudo- propositions. By “pseudo-propositions,” Ayer means a sequence of words that assumes the form of a coherent sentence but is actually meaningless.[1] The content of a proposition is considered meaningless when it is neither empirically observable (i.e. perceivable through the five senses) nor a prima facie proposition. In order for a proposition to be prima facie, it must be intuitively self-evident: tautologies, pure definitions, and basic truths of mathematics and logic are some examples.[2] Ayer appeals to a “criterion of significance” that establishes certain conditions which must be fulfilled in order for a proposition to be granted the title of a significant proposition. In Ayer’s view, “significant propositions,” are either analytic (i.e. prima facie) or synthetic (i.e. empirically observable) statements, which in principle are verifiable and meaningful.[3] Unfortunately, Christianity does not meet Ayer’s criterion. If Christians insist that theology does in fact refer to something meaningful, it will be important to show that Ayer’s argument fails to establish the criterion of significance as a viable methodology. In this paper, I will refute A. J. Ayer’s argument for the impossibility of metaphysics on account of its absurd ethical implications, its fallacious methodology, and its inherent self-refuting claims.

1. A. J. Ayer, “Demonstration of the Impossibility of Metaphysics,” Mind 43, no. 171 (1934): 335,
2. Ayer, 337.
3. Ayer, 345.


Ayer purports to demonstrate that all metaphysical questions and propositions about the nature of reality are pseudo-propositions that merely express one’s feelings but in themselves are meaningless. In comparison to the scientific method for obtaining knowledge, the metaphysician cannot obtain knowledge, because none of the metaphysician’s alleged knowledge can be verified. As a consequence, the metaphysician can say nothing about ultimate reality, that is, the parts of the world beyond empirical observation. Kant believed that there may in fact be an ultimate reality, but we cannot gain knowledge of it through reason (a being such as God might have knowledge of it, even if its existence could not be proven). For Ayer, to assert that ultimate reality does or does not exist is to declare a pseudo-proposition. The idea of a god possessing knowledge of ultimate reality is, says Ayer, not a meaningful hypothesis. Kant’s difficulty with humans gaining knowledge of ultimate reality is a non-starter for Ayer. According to Ayer, there is no metaphysical knowledge to be gained — full stop.[4]

To demonstrate the impossibility of metaphysics, Ayer appeals to a methodology that he titles the “criterion of significance” through which the truth of all prima facie propositions may be evaluated.[5] Ayer’s criterion establishes certain conditions that must be fulfilled in order for a proposition to be granted the title of a significant proposition. The conditions are simple: a proposition may be understood and be either true or false when the facts verify it. If the facts verify the proposition, it is a significant proposition.[6]

Ayer gives an example of someone calling his cat “corylous.”[7] This person uses the word “corylous” to mean that Ayer’s cat has blue eyes. If “having blue eyes” establishes the truth or falsity of something “being corylous,” then this is verifiable and expresses a significant proposition. However, if Ayer’s cat is called “corylous,” and nothing about the cat verifies this proposition, it is meaningless. If the speaker means something by the word “corylous” that is unobservable, then it only means that he has feelings connected to the sound of the word “corylous” but does not say anything meaningful.[8]

To justify his methodology, Ayer concedes that he has presupposed a certain notion of meaning that cannot be explained by appealing to other basic facts. Ayer’s project, however, is not to demonstrate that this presupposition is true or false but rather to show that the criteria of significance “should be” employed.[9] The veracity of the criterion of significance is determined by checking if the conclusions generated are correct. This is circular, Ayer admits, but the possibility of psychologically intuiting that certain propositions are significant breaks the circle. There are, for instance, prima facie propositions that are universally accepted as significant and other propositions universally deemed meaningless. The criterion of significance may be trusted if it accepts the proper category. In this way, all doubtful propositions made by metaphysicians can be tested by the criteria. If the criteria are considered too restrictive, the onus is on the metaphysician, says Ayer, to put forth a charitable criteria — one which excludes meaningless phrases. Unless this alternative type of criterion is established, there can be no objections to Ayer’s methodology and no escape from his conclusion.[10]

The implications that follow from Ayer’s account are predictable. Propositions that cannot be verified are not propositions. The foundational tenant of metaphysical study which claims there is an ultimate reality that exceeds the empirical world is not a proposition; no observable phenomena could verify the truth or falsity of that metaphysical assertion. Analytical truths and synthetic propositions, even certain speculative synthetic statements are in principle verifiable. The assertions of metaphysics, however, are “in principle unverifiable.”[11] Whereas hypotheses have grounds in empirical data, metaphysical hypotheses are not hypotheses by definition because they have no grounds in observation.[12]

Ayer attempts to solidify his argument by responding to three popular objections. The first objection asks why assertions about ultimate reality were made if they are obviously meaningless. Ayer explains that these assertions arise through errors of reasoning by means of improper grammatical construction. Some philosophers speak of an imaginary illness having the property of existence, which is wholly spurious. The proper rephrasing of “his illness is imaginary” ought to be “he is not ill although he thinks he is”; existence, says Ayer, is not a property.[13]

The second objection questions why nonsensical metaphysical claims are made so often. Ayer believes that some philosophers are not content to make observations about physical reality but decide to express their feelings. As a result, what is typically reserved for literature is inappropriately asserted in philosophical contexts — a simple category mistake. A similar problem arises when the metaphysician seeks to understand the world but being too incompetent to grasp the mechanisms of science, he hypothesizes a new form of knowledge, which is actually about nothing.[14]

The third objection wonders how sophisticated philosophers seemed to say something about the nature of reality, when in fact they said nothing. Ayer thinks it’s perfectly charitable to ancient, distinguished philosophers to strip away all metaphysical assertions from their texts and leave their empirical discoveries and analytic statements. This is considered a pious demonstration of respect for our intellectual forbearers.[15]

4. Ayer, 336.
5. Ayer, 337.
6. Ayer, 337.
7. Ayer, 337.
8. Ayer, 338.
9. Ayer, 343.
10. Ayer, 345.
11. Ayer, 340.
12. Ayer, 339–340.
13. Ayer, 341–342.
14. Ayer, 342.
15. Ayer, 343.


There are three core problems with Ayer’s argument. First, Ayer claims that only synthetic and analytic propositions are meaningful; Ayer effectively renders all ethical propositions as merely emotional outbursts. This directly contradicts our ethical intuitions and leads to abhorrent conclusions. Second, Ayer’s methodology excludes the possibility of metaphysical inquiry, and then, upon implementation, Ayer’s methodology concludes that metaphysical inquiry is impossible. This is obviously question-begging. Third, Ayer’s criterion of significance actually refutes Ayer’s argument. I will discuss each in turn.

In The Brothers Karamazov, Fyodor Dostoyevsky’s provides a famous example of evil narrated by the nihilistic Ivan Karamazov: “These Turks took pleasure in torturing children… cutting the unborn child from the mother’s womb, and tossing babies up in the air and catching them on the points of their bayonets before their mothers’ eyes.”[16] If Ayer’s criterion of significance is correct, it would be a pseudo-proposition to say that “bayonetting babies in front of their mothers is evil,” as if that were a verifiable fact. This directly contradicts our moral intuitions. Even if some people can’t “see” this, we say, moral knowledge is still possible. Some people may suppress this knowledge or become culturally blinded, but instances like Dostoyevsky depicts provide strong intuitive evidence for objective morality. For Ayer, instances of allegedly good or evil behavior can only be observations of behavior. “Good” and “evil” do not refer to anything metaphysical; they are symbols of emotion and symptomatic of societal pressures and negotiated codes of conduct. However, this ethical stance leads to many undesirable outcomes. When the Nazis, for example, put Jews and other minorities into concentration camps, we can only express emotions about this nation state’s behaviour. We cannot criticize their behaviour or complain that they have done anything wrong.

Ayer might respond by pointing out how legislating bodies grant certain rights to humans whenever it’s deemed appropriate to preserve societal harmony. The legal system decides which activities are right and wrong; the Nazi’s legislation did not ensure societal harmony — that’s why it was wrong. It may be true that a nation state’s legislation is typically designed to ensure societal harmony (i.e. order); however, if the legislation does not derive its moral principles and values from universals but merely its own legislating body, who is to say which legislating body correctly assigns human rights? For neither nation-state derives their moral principles and values from anything beyond a subjective, arbitrary product of social conditioning. In other words, if Ayer’s notion of ethics is correct, the Nazis did nothing wrong. This is an untenable conclusion.

The second problem with Ayer’s argument is that his methodology of determining significant propositions is blatantly question-begging. In Warranted Christian Belief, Alvin Plantinga critiqued Historical Biblical Criticism (HBC) with an analogy that is particularly relevant to Ayer’s view. Imagine, says Plantinga, that an attorney offers to investigate your friend’s innocence but does not accept the testimony of your memory or the fact that you remember your friend being in your office and “precludes from the start” the innocence of your friend, “even if he is innocent.”[17] It is no wonder, Plantinga surmises, that HBC yields such restrictive conclusions when it holds presuppositions that exclude the primary Christian beliefs known via faith and divine revelation. Ayer is employing the same methodology as HBC but only in a different context. Ayer establishes a criterion with certain conditions that must be fulfilled in order for a proposition to be granted the title of a significant proposition. Ironically, these conditions, from the very start, rule out any possibility of metaphysical propositions passing the criterion. It is no wonder that Ayer yields the result of metaphysical propositions being pseudo-propositions when his criteria eliminated the possibility of them being otherwise.

Ayer might respond by claiming that all inquiries into the meaning of propositions must presuppose certain notions without an explanation to more basic facts. The problem with Ayer’s methodology, however, is that it presupposes exactly what it plans to show. Ayer does not follow where the evidence leads him through questions and research, as philosophical inquiry generally requires. Instead, Ayer axiomatically rejects all metaphysical evidence and proceeds to assert question-begging notions about reality. This enters a realm of dogma usually reserved for cultists, certain religious creeds, and political parties. It’s clearly fallacious reasoning.

A final objection to Ayer’s argument originates from Alvin Plantinga; the basic contention is that Ayer’s argument is inherently self-refuting. Ayer’s criterion states that a proposition may be understood and be either true or false when the facts verify it. If the facts verify the proposition, it is a significant proposition. Ayer allows synthetic and analytic propositions to pass his criterion. Unfortunately, Ayer’s criterion of significance does not pass the criterion of significance — neither, for that matter, does Ayer’s argument. Both Ayer’s criterion and argument are neither empirically verifiable nor are they analytic truths. Ayer’s project is founded upon contradiction, and consequently, it is false.

Ayer might respond that the criterion of significance is a useful construct to determine the meaning of propositions by testing them against the criterion (which consequently has intuitive psychological support from universal agreement about prima facie propositions). Ayer’s criterion, however, would still be unhelpful in determining the meaning of propositions, because it is far too restrictive. If Ayer’s philosophical argument cannot even pass Ayer’s criteria, which it was designed to support, this shows an error in reasoning — not a useful construct. The criterion of significance is patently useless.

Ayer’s abhorrent ethical implications, blatant question-begging methodology, and self- refuting criteria of significance demonstrate that his argument is unsound. Ayer’s purpose was to demonstrate the impossibility of metaphysics; instead, he demonstrated the impossibility of constructing a sound argument with fallacious premises.

16. Fyodor Dostoyevsky, The Brothers Karamazov, trans. Constance Garnett (Auckland: The Floating Press, 2009), 462,

17. Alvin Plantinga, Warranted Christian Belief. (New York: Oxford University Press, 2000), 414,


Ayer, A. J. “Demonstration of the Impossibility of Metaphysics.” Mind 43, no. 171 (1934): 335-45.

Dostoyevsky, Fyodor. The Brothers Karamazov. Translated by Constance Garnett. Auckland: The Floating Press, 2009. k&AN=332824&site=ehost-live&scope=site.

Plantinga, Alvin. Warranted Christian Belief. New York: Oxford University Press, 2000. k&AN=55794&site=ehost-live&scope=site.