At the age of 26, philosopher A.J. Ayer published one of the most widely read (and heavily criticized) philosophical treatise of the twentieth century, Language Truth and Logic (Click here to read a condensed version for free). Ayer introduced the principle of verification as a principle to sort meaningful sentences from gibberish. In essence, it says that in order for a statement to have literal meaning it must be either true by definition (A equals A) or empirically verifiable (some observation or sensory experience is relevant to establishing the statement as true or false). Ayer expounds upon this:
A sentence is factually significant if, and only if, we know how to verify the proposition it purports to express – that is, if we know what observations would lead us to accept the proposition as true or reject it as false.
A simple example would be the proposition that there are mountains on the other side of the moon. No rocket has yet enabled me to check this, but I know it to be decidable by observation. Therefore this proposition is verifiable in principle and is accordingly significant. On the other hand with such metaphysics as “the Absolute enters into, but is itself incapable of, evolution and progress” [FH Bradley] one cannot conceive of an observation which would determine whether the Absolute did or did not enter into evolution; the utterance has no literal significance.
A proposition is verifiable in the strong sense if, and only if, its truth could be conclusively established by experience. It is verified in the weak sense if it is possible for experience to render it probable.
If we adopt conclusive verifiability as our criterion of significance, our argument will prove too much, for even general laws such as “all men are mortal” or “arsenic is poisonous” cannot be established with certainty by any finite number of observations. Nor can we accept that a sentence should be allowed to be factually significant if, and only if, it expresses something definitely confutable by experience [Karl Popper]. A hypothesis cannot be conclusively confuted any more than it can be conclusively verified.
Accordingly, we fall back on the weaker sense of verification. We say that the question that must be asked about any putative statement of fact is not, Would any observations make its truth or falsehood certain? but simply, Would any observations be relevant to determination of its truth or falsehood?
Ayer claimed David Hume as an early proponent of his view, citing Hume’s infamous passage from An Enquiry Concerning Human Understanding:
If we take in our hand any volume of divinity or school metaphysics, for instance, let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion.
Though we can’t be sure, I believe Hume meant not that metaphysics and theology are gibberish/nonsense as Ayer believed, but that the propositions of such volumes were not inferences from any solid ground of knowledge (like observation or logic).
In any case, Ayer’s book expounded upon a number of startling conclusions, such as: Much of Philosophy, especially Metaphysics, is Nonsense * Ethical Statements are nothing more than proclamations of emotion * “Caesar crossed the Rubicon” means nothing more than “If you look in the history books, you shall find that they report ‘Caesar crossed…'” * The statement “God exists” is without meaning * Life After Death is a contradiction in terms * And much more.
I am a verificationist, of a very unusual sort: I agree with a version of the verification principle, but strongly disagree with Ayer on just about all of the conclusions he derives from it and nearly everything else in Language, Truth and Logic. So, ah, this’ll be interesting.
Criticism of the Verification Principle: It is redundant.
The first correction I want to make to Ayer’s verification principle is its two prongs ought to be reduced to one. The principle says that meaningfulness requires that a statement be either true by definition or empirical. My version of the verification principle says only that all meaningful statements must specify an experience [or set of experiences, or absence of experience(s)] that someone could theoretically have. In one stroke this covers not only scientific theories but also logical statements like “A equals A.” Statements like this specify the experience which they themselves deliver: “A equals A” means that the symbol on one side of the equal sign is the same as the symbol on the opposite side, and we can immediately verify this just by looking at the statement and observing this ourselves. I’d also add that I believe Crispin Wright’s new version of the verification principle (which seems to me a little inelegant and almost contrived) could probably be reduced down to my simpler formulation of it.
Does the Verification Principle Contradict Itself?
The most common criticism of the verification principle is that it is self-contradictory. Applying this criticism to Ayer’s formulation of the verification principle, one would say that the verification principle itself is not true by definition or empirically verifiable/falsifiable. I disagree completely, and think that Ayer’s verification principle has never suffered from this problem.
Let me explain: one of the things philosophers do is come up with theories about what words mean. We throw around quite a few words without ever bothering to explicate a precise definition for them. Case in point: what is knowledge? Out of all the statements, feelings, and ideas floating around in your head, what is it that makes some of them knowledge and others not? Long ago it was commonly accepted that a piece of knowledge was nothing more than a belief that one justified and which was also true (a justified true belief). That was a theory about what knowledge meant. In the 1960’s this theory had to be revised because a man named Edmund Gettier pointed out that we don’t feel that a belief qualifies as knowledge, even if it is true and justified, if it has been justified on the basis of misleading evidence. So, the “justified true belief” theory about what the word knowledge means was falsified and ever since philosophers of knowledge have been proposing new theories that take Gettier’s criticism into account. Theories about what words mean can be refuted empirically, simply by showing that the proposed definition doesn’t quite fit the way most people use the word it purports to define. What Ayer did was to propose a theory about what the word “meaning” means: “meaning” is one and the same as “either true by definition or empirically verifiable.” As such, Ayer’s theory can be corroborated with every statement that most people find meaningful and also conforms to Ayer’s definition of meaningfulness, and it can be refuted if we find a statement that most people feel is meaningful but flunks Ayer’s definition (for that would show that Ayer’s definition of meaning does not quite capture what meaning is). The same goes for my new verification principle: if a single statement can be found that most people believe to be meaningful but which does not specify an experience someone could possibly have, then it is false and we must seek a new account of what meaning is. It can be partially corroborated every time we examine a statement that we feel is meaningful and conforms to it, and it could be conclusively verified if human language could be exhaustively examined (perhaps by a super-computer of the future) to check whether all statements that humans feel are meaningful conform to the principle. [Feel free to skip this bracketed section if you wish. In addition to this argument, I have also found a useful philosophy page which shows that the verification principle logically follows from Empiricism and Wittgenstein’s picture theory of meaning, though I suspect you could substitute the picture theory with the reference theory of language and get the same result. So long as one takes those two premises, empiricism and picture theory or reference theory, if those two premises can be supported by experience then the conclusion, as a matter of logical experience, is also supported and the verification principle ceases to be self-refuting because it can indeed pass its own test. This argument and/or the one that I have given refutes the argument from self-contradiction and offers great support to the verification principle].
The String Theory Objections
Now let me skip over to some of the problems facing verificationism that I think are the most interesting. Does the verification principle render string theory meaningless talk? After all, scientists at present are unsure what experiences are relevant to determining its truth or falsity (they don’t know how to test it). There are several components of string theory worth talking about: on the one hand, the thesis that matter is, at the smallest level, composed of string-like things vibrating at different frequencies is certainly a potentially observable phenomenon. At the moment we don’t have a microscope powerful enough to view this and we might never, but nonetheless this thesis of string theory does pass the verification principle. A.J. Ayer ran into a similar problem with the theory of atoms, and he claimed, rather implausibly, that atomic theory had no further meaning than the indirect predictions it made which scientists could verify. If Ayer had been able to peer into twenty-first century when he wrote this, he might’ve felt a bit silly. Why? Because scientists have now directly observed electrons. Of course atomic theory means more than the “if-then” statements scientists use to test it; it means that at a very tiny scale one would observe things with the properties and behaviors that atomic theory describes. Likewise, string theory is saying that if you could see things at the smallest scale, what you would observe is strings vibrating at different frequencies. This component of string theory passes the principle. What about the thesis that reality has nine dimensions? This is not observable, and it may never be observable. Does this example falsify the new verification principle? There are several important considerations to make: 1) Even if string theory does not pass the verification principle, we should still pause to examine whether this should be taken as indicating the principle defective. After all, every person whom I have ever talked to, including many non-verificationists, admit that they have a hard time grasping the concept of what it would mean for there to exist other dimensions. They cannot picture it, and even have trouble grasping the idea that other dimensions are even possible. 2) We know what a dimension is, and we can explicate the concept in terms of sensory data: a dimension is place or a direction in which matter can move. Multiplying this concept to a number greater than we are able to sense or even imagine can, to some small degree, be understood precisely because it is just a multiplication of something we already have experience with. 3) If there are other directions in which things can move around, then it would seem, at least in theory, that there could be an instrument or a possible creature that could have the sensory organs to detect such things, in which case the hypothesis would specify a possible experience someone would have, and thus it would pass the verification principle. After quite a bit of consideration and mental probing I have done on my own, the string theory objections are the strongest ones I can find to my position, and I think if they are the worst objections, the verification principle still recieves my tentative approval. For the vast majority of statements that I feel are meaningful, they too, as far as I can see, only translate into possible experiences. The one potential exception that I have found (the proposition that there are more than 3 spatial dimensions) is very doubtful in its own right. [Update: Since I first wrote this post I have begun to reconsider this. If we could build an uber-tiny nanorobot, we could begin to probe the smallest level of reality, and as such we might verify the proposition that only three spatial dimensions exist, thereby falsifying the proposition that nine spatial dimensions exist but some of them are too small for we humans to sense].
There are a handful of naive objections to the verification principle that come from the likes of Alvin Plantinga and William Lane Craig. I won’t address all of them, instead I’ll look at just two: First, the statement “The external world exists” seems to be meaningful, yet it seems to be something we cannot verify, because all of our sensations and perceptions of the world around us might just be an illusion generated by The Matrix. Though the movie itself proves that there are ways of falsifying the thesis that the world we currently experience is an illusion (by having an experience of waking up from the Matrix and getting out) it is also true that if the world we live in were not real, someone could have an experience that indicated that. For example, if my whole life is nothing more than the result of a mad scientist stimulating my brain to induce the experiences I have, then that scientist would have the experiences to know that my world was an illusion, which means that the external world thesis does indeed pass my version of the verification principle, since it only says that a meaningful statement must specify a possibly experience someone could have (not necessarily an experience that you personally could ever have).
Second, it has been claimed that the statement “other people have conscious minds and experiences” would be rendered meaningless by the verification principle. More specifically, a big discussion has gone on amongst philosophers of mind about how exactly we know that other people are not like robots, that they really feel pain when a needle pricks them, since it seems that we cannot observe the private feelings of other people, only their outward behavior, which could conceivably occur without the inner feelings that we know accompany such feelings. AJ Ayer seemed to believe the whole debate was meaningless, that other people being conscious refers to nothing more than the behavior of their bodies that we associate with having consciousness, and hence that there was no legitimate question to solve. My new verification principle avoids the embarrassing corner Ayer was painted into because it doesn’t say that you have to personally have direct awareness of other people’s inner conscious experience in order for the question of whether they have to be meaningful (though I believe there are philosophical arguments which allow you to know that they are conscious, but that’s another story for another day), it only says that someone has to be able to have the experiences of conscious awareness in order for it to be a meaningful statement. And clearly statements about other minds pass that test: If you wonder whether or not your friend Mary is a philosophical zombie (one who has no conscious experiences, but only acts like they do, like a robot) it doesn’t matter that you cannot have experiences of her private emotions and experiences, because she can, and hence her conscious experience is what must be had by someone (in this case, her) that makes the question of her sentience something to be settled by experiences.
Can the Verification Principle Serve Any Useful Philosophical Function?
The usefulness of the verification principle has also been questioned. Though its usefulness does not necessarily affect its status as truth, I think this objection is worth looking at nonetheless. It has been argued that if the verification principle ruled out any sentence that we felt was meaningful, this would indicate the verification principle was false. On the other hand, what is the point of having a principle to distinguish meaningful statements from meaningless ones if it does not exclude anything at all? It would inform us of nothing and have no practical use. I think the verification principle can be useful in helping us decide upon the meaningfulness of statements if they are called into question not merely by the verification principle but also by common sense or intuition. For example, I am skeptical, independently of verificationist considerations, about whether some of Deepak Chopra’s statements (or those of high-brow ivory tower theologians) are genuinely meaningful. The verificationist principle, which I believe is probably correct for reasons given previously, provides a more objective way to settle my suspicions in such cases and to demonstrate the meaninglessness of these statements to others. Chopra and the ivory tower theologians can protest all they want to the contrary, but the fact is that their belief in the meaningfulness of these statements is extremely questionable. They cannot explain what the meaning of these statements is, they cannot offer a definition of meaning that fits the way most people use the word. Therefore my verificationist position, which marshalls empirical evidence in its favor (the word “meaning” does seem to mean what I say it does, after careful analysis of how the word is used) combined with my gut instinct on the matter, settles the case in my favor.
What are the Consequences of Verificationism to Theology?
Does the verification principle render talk of gods meaningless? I think it depends on what type of God we’re talking about. If we’re talking about the deity that I think most people believe in, who is basically an experience-having person without a body, then this certainly is meaningful, as this God could verify his own existence. The common man’s deity has feelings and emotions, and such a being would only have to recognize the fact that he is having thoughts in order to verify his existence. The god that theologians talk about, who is an entity outside of time, lacking anything analogous to a succession of thoughts, emotions firing on and off, etc. and which is not in any sense a physical thing or something that could ever be detected by the five senses is not a verifiable proposition.
It remains a mystery to me why verificationism is a minority position in academia today. It seems to have a lot going for it. If it can be refuted then somehow none of the good refutations of it have ever become popular, and all the popular refutations of it are pretty trivial and easy to rebut. However, I am interested in hearing from those who believe otherwise. So, fellow bloggers, “The verification principle is right!” Discuss. ; )
Addendum: Recent Verificationist Works
CJ Misak, Verificationism: Its History and Prospects.
Brian Clack, “Religious Belief and the Disregard of Reality,” in Moral Powers, Fragile Beliefs.
Also see the works of Michael Martin, Michael Dummett, Kai Nielsen and Daniel Dennett.