Nonsense is an utterance or written text in what appears to be a human language or other symbolic system, that does not in fact carry any identifiable meaning.

Table of contents
1 Distinguishing sense from nonsense
2 Teaching machines to talk nonsense
3 Literary nonsense
4 The philosophy of nonsense
5 See also

Distinguishing sense from nonsense

Distinguishing meaningful utterances from nonsense is not a trivial task. Confronted with a lengthy text in an unknown script, could you in fact determine whether those characters in fact contained a meaningful text, or were simply set using the equivalent of printer's pi or a lorem ipsum style text? The problem is important in cryptography and other intelligence fields, where it is important to distinguish signal from noise. Cryptanalysts have devised algorithms for this purpose, to determine whether a given text is in fact nonsense or not. These algorithms typically analyse the presence of repetitions and redundancy in a text; in meaningful texts, certain frequently used words -- for example, the, is, and and in a text in the English language -- will occur over and over again. A random scattering of letters, punctuation marks, and spaces will not exhibit these regularities. Zipf's law attempts to state this analysis in the language of mathematics. By contrast, cryptographers typically seek to make their ciphertexts resemble random distributions, to avoid tell-tale repetitions and patterns that may give an opening for cryptanalysis.

Teaching machines to talk nonsense

It is far harder for cryptographers to deal with the presence or absence of meaning in a text in which the level of redundancy and repetition is higher than found in natural languages: for example, in the mysterious text of the Voynich Manuscript. Some have attempted to create text that in fact carries no meaning, but still complies with the regularities predicted by Zipf's law. The Markov chain technique is one such method. This has occasionally been put into the service of surrealistic jokes; the fake Usenet poster Mark V Shaney posted texts generated by a Markov chain algorithm, and frequently launched flame wars with his unfathomable screeds.

The Markov chain technique is one method that has been used to generate texts by algorithm and randomizing techniques that seem meaningful. Another could be called the Mad Libs method: it involves the creation of templates for various sentence structures, and filling in the blanks with noun phrases or verb phrases; these phrase generation procedures can be looped to add recursion and give the output the appearance of greater complexity and sophistication. Racter was a computer program that generated nonsense texts by this method; unfortunately, Racter's book, The Policeman's Beard is Half Constructed, proved to have been the product of heavy human editing of the output of the program.

Literary nonsense

The phrase "Colorless green ideas sleep furiously" was coined by Noam Chomsky as an example of nonsense. The individual words make sense, and are arranged according to proper grammar, yet the result is still nonsense. The inspiration for this attempt at creating verbal nonsense came from the idea of contradiction and irrelevant or immaterial characteristics (an idea cannot have a dimension of color, green or otherwise), both of which would be sure to make a phrase meaningless. The phrase "the square root of Tuesday" operates on the latter principle. This principle is behind the inscrutability of the koan "What is the sound of one hand clapping?", as one hand would supposedly require another hand to complete the definition of clapping.

Still, the human will to find meaning is strong; green ideas might be ideas associated with a Green party in politics, and colorless green ideas criticises some of them as uninspiring. For some, the human impulse to find meaning in what is actually random or nonsensical is what makes people find luck in coincidence, or believe in omens and divination.

The dreamlike language of James Joyce's "novel" Finnegans Wake sheds light on nonsense in a similar way; full of portmanteau words, it appears to be pregnant with multiple layers of meaning, but in many passages it is difficult to say whether any one person's interpretation of a text is the "intended" or "correct" one. There may in fact be no such interpretation.

Nonsense verse

Nonsense verse represents a long tradition; its best known exponent is Edward Lear, author of The Owl and the Pussycat and hundreds of limerickss. But according to Douglas R. Hofstadter, the crowning achievement in a nonsense limerick goes:

There once was a man of St Bees
Who was stung in the hand by a wasp;
When asked, "Does it hurt?"
He replied, "Yes, it does,
I'm so glad it wasn't a hornet."

a "limerick" that does not rhyme and is not funny, which makes it funny. The above limerick was actually a parody of Lear's limericks by W. S. Gilbert. Similar to the limerick is the clerihew.

Nonsense verse represents a tradition older than Lear; the nursery rhyme Hey Diddle Diddle is also a sort of nonsense verse. Lines of nonsense frequently figure in the refrains of folksongs. Nonsense riddles and knock-knock jokes are seen often. Lewis Carroll, seeking a nonsense riddle, once posed the question How is a raven like a writing desk? But someone answered him, Because Poe wrote on both. However there are different answers.

In the field of Art, the Dadaism movement created nonsense art as an expression of disaffection with art and a society that seemed unavoidably addicted to the insanity of war.

The philosophy of nonsense

Philosophically, nonsense masquerading as sense is the gist of the charges of pseudoscience and pseudophilosophy. Karl Popper's notion of falsifiability is an attempt to create an axiom for distinguishing sense from nonsense in the field of science; its validity remains controversial in the philosophy of science.

See also