“Nonsense” is an ambiguous word that conflates a lack of coherent meaning, a profound defect in the chain of reasoning (which excludes even falsity), and a flaunting of common sense. In literature, nonsense is often the outcome of a multiplicity of possible, usually mutually-exclusive meanings.

In certain disciplines (cryptography, information theory, communication theory) nonsense is described as “random noise” (as distinct from “signal”) with specific characteristics of randomness, repetition, and redundancy of the symbols comprising it as expressed via its specific frequency distribution. But all these definitions rely on an intimate acquaintance with the meaning of the nonsensical statement and on the ability to prove that it is not verifiable, confirmable, or, more fashionably, falsifiable. This is where the boundaries between nonsense and falsity begin to blur.

The principle of verifiability of statements veers dangerously close to circularity and even tautology. The meaning of a statement is the method for its verification. Yet, the (cognitive) meaning of a statement also depends crucially on its verification! To quote “The Oxford Companion to Philosophy”: “A statement is meaningful if and only if it is in principle verifiable.” Yet, of course, a sentence can be meaningful and false.

“To ask whether a claim is verifiable and conclude that it is not, it looks as though I have to first understand the claim, ie give a meaning to it. How then can I add that because it is unverifiable it is meaningless?” (Ian Dearden, “Do Philosophers Talk Nonsense? – An Inquiry Into The Possibility Of Illusions Of Meaning”, Teller Press, 2005.”)

Moreover, it is fiendishly difficult to verify analytic statements (e.g., mathematical theorems) because verification often relates to observable facts (logical positivism, logical empiricism) rather than to algorithms and calculations. There is also the issue of context: “... (A)ny statement will have verifiable implications if con-joined with suitably chosen others.” (ibid.)

Nonsense relies on inconsistency and, therefore, unpredictability. Though it may be subject to implicit or explicit rules, nonsense obeys no logical constraints, whether internal or external. This is the main reason logical fallacies are nonsensical – not only because they are manifestly false.

Nonsensical statements – as well as the sense-less tautologies and propositions of logic and mathematics - do not correspond with reality (in Wittgenstein’s terms: do not refer to or represent facts or factual states of affairs; are not “in the world”, but at its limit; have no truth value.) They are statistically rare (extremely infrequently formed or used). Nonsense has to be verbalized. It cannot be “shown”, pointed at, or experienced directly. Nonsense must be said and, thus, is an artefact of language itself, one of its cornerstones and a boundary condition (“limit”.) Nonsense is where meaning stops.

Indeed, many puzzles and enigmas appear to be nonsensical because of this tension between structure/rule/abstraction and logic/meaning/reality. Solving the riddle, however, involves “outing” the logic that governs it, thereby rendering it perfectly “sensical” in the real world.

In all these considerations, nonsense is largely identified as such by its lack of reference to the world we know. Could some nonsense make sense in other, possible worlds? Would all nonsense perforce make sense somewhere, in one or more possible worlds out of the infinite number of possible worlds? Not if these universes are all ruled by logic, mathematics, and the Laws of Nature.

Disparate as these possible worlds may be, they must conform and adhere to a set of immutable, universal principles which give us meaning and coherence and yield truth and sense. Nonsense is nonsense across all possible worlds. Indeed, nonsense delineates the parameters and boundaries or limits of those worlds which are impossible. If some statement or claim is possible then it is not nonsensical. So, the useful test is not whether something we say corresponds to reality, refers to it, represents it, or “shows” it (points to it.) It is whether a statement or claim we make can, in principle, in some possible world, correspond to that world’s reality, refer to it, represent it, or “show” it (point to it.)

Nonsense can serve as useful background in contrast to which sense can be constructed, surmised, deduced, or construe d. Nonsense can also function as the context within which sense is outstanding. Indeed, literary nonsense makes use of numerous devices to achieve precisely this contradistinction. In literary nonsense, formally impeccable literary forms purposefully sit ill with faulty cause and effect, portmanteau, neologism, reversals and inversions, imprecision, simultaneity, picture-text incongruity, arbitrariness, infinite repetition, negativity and mirroring, misappropriation, tautology, reduplication, and absurd precision. This incongruence forces the mind to seek meaning and order where there is merely structure.

Peter Schombert suggests these two cumulative tests:

“(T)he best way to detect nonsense is simply by considering what the world would be like if the claim being considered was false, and some competing claim was true . If the world would be exactly the same, or the possibility of the claim being false is incoherent, then there is a good chance that the claim in question is nonsense.”