Nonsense is a way of communicating through speech, writing, or other systems that do not have clear or logical meaning. In everyday language, nonsense is often used to mean something silly or unreasonable. Many writers, such as poets, novelists, and songwriters, have included nonsense in their work. They sometimes create whole pieces using nonsense for reasons like making people laugh, criticizing ideas, or showing how language and thinking work. In the study of language and science, nonsense is different from meaningful ideas. People have tried to find a clear and reliable way to tell the difference between meaningful and nonsense ideas. Nonsense is also important in the study of cryptography, where experts work to separate useful information from random or meaningless data.

Literary

The phrase "Colorless green ideas sleep furiously" was created by Noam Chomsky as an example of nonsense. Each word in the phrase is meaningful and follows correct grammar rules, but the phrase itself does not make sense. This idea comes from the use of words that seem unrelated or conflicting, making the phrase hard to understand. For example, the phrase "the square root of Tuesday" also uses unrelated ideas. A similar concept appears in the kōan "What is the sound of one hand clapping?" because one hand cannot make a sound by itself.

Jabberwocky is a nonsense poem written by Lewis Carroll in his book Through the Looking-Glass, and What Alice Found There (1871). The word "jabberwocky" is sometimes used to describe nonsense.

Nonsense verse is a type of literary nonsense, often found in poems. Edward Lear, a famous writer, is well known for this style. His works include The Owl and the Pussycat and many limericks. Nonsense verse has a long history, even before Lear. For example, the nursery rhyme Hey Diddle Diddle could also be called nonsense verse. Some songs, like the 1940s song Mairzy Doats, appear to be nonsense verse but are not.

Lewis Carroll once asked a nonsense riddle: "How is a raven like a writing desk?" One answer was "Because Poe wrote on both." Other answers, such as "Both have inky quills," are also possible.

The first verse of Jabberwocky by Lewis Carroll:
"Twas brillig, and the slithy toves Did gyre and gimble in the wabe; All mimsy were the borogoves, And the mome raths outgrabe."

The first four lines of On the Ning Nang Nong by Spike Milligan:
On the Ning Nang Nong Where the cows go Bong! and the monkeys all say BOO! There's a Nong Nang Ning

The first verse of Spirk Troll-Derisive by James Whitcomb Riley:
The Crankadox leaned o'er the edge of the moon, And wistfully gazed on the sea Where the Gryxabodill madly whistled a tune To the air of "Ti-fol-de-ding-dee."

The first four lines of The Mayor of Scuttleton by Mary Mapes Dodge:
The Mayor of Scuttleton burned his nose Trying to warm his copper toes; He lost his money and spoiled his will By signing his name with an icicle quill;

Oh Freddled Gruntbuggly by Prostetnic Vogon Jeltz, created by Douglas Adams:
Oh freddled gruntbuggly, Thy micturations are to me As plurdled gabbleblotchits on a lurgid bee. Groop I implore thee, my foonting turlingdromes, And hooptiously drangle me with crinkly bindlewurdles, Or I will rend thee in the gobberwarts With my blurglecruncheon, see if I don't!

Philosophy of language and of science

In the study of language and science, the term "nonsense" describes something that lacks meaning or sense. Different definitions explain how meaning is separated from nonsense.

Ludwig Wittgenstein, a philosopher, used the word "nonsense" in a special way. For him, "nonsense" did not mean random, meaningless words. Instead, it referred to statements that lacked sense in specific contexts, such as those involving logic or mathematics. For example, the statement "1+1=2" might be considered nonsensical in certain philosophical discussions. Wittgenstein wrote in his book Tractatus Logico Philosophicus that some of his own ideas should be seen as nonsense. In this context, the word "nonsense" does not always have negative meanings.

In Wittgenstein’s later work, Philosophical Investigations, he explained that some ideas appear to be "disguised nonsense" but are actually nonsense in a hidden way. He used the example of G. E. Moore’s attempt to prove that the external world exists, such as when Moore said, “Here is one hand.” Moore’s argument seemed meaningful but failed because it addressed a problem that did not exist. Wittgenstein argued that meaning comes from how people use language in specific situations, not from the structure of sentences alone.

Wittgenstein believed that some statements express basic beliefs that act as "hinges" for understanding. These hinges help define the rules for thinking about certainty and doubt. He wrote, “If I want the door to turn, the hinges must stay put.” He also noted that if someone cannot be certain about facts, they cannot be certain about the meaning of their words. Moore’s argument and philosophical skepticism (the idea that we cannot know anything for sure) were both considered nonsense because they violated the rules of meaningful thinking.

Some philosophers, like Cornman, Lehrer, and Pappas, argued that philosophical skepticism is meaningful in terms of language but seems nonsensical in terms of knowledge. For example, the sentence “Worms integrate the moon by C# when moralizing to rescind apples” is meaningless in language (semantic nonsense) because it has no clear meaning. However, the statement “We know nothing whatsoever” is grammatically correct but appears extremely false (epistemic nonsense). The problem is not the sentence itself but the idea of saying it, which seems unreasonable.

Leonardo Vittorio Arena, an Italian philosopher, expanded on Wittgenstein’s ideas. He argued that nonsense can highlight the lack of meaning in the world and life, challenging views that rely on fixed ideas or logic. He connected this to the ideas of the Indian philosopher Nagarjuna, who rejected the idea of opposites and traditional logic.

Cryptography

It is important to tell the difference between meaningful information and meaningless information in cryptography and other intelligence areas. For example, experts need to identify useful signals in a mix of useful and useless information. Cryptanalysts have created methods to check if a text is truly meaningless. These methods usually look for repeating patterns and repeated words in a text. In meaningful English texts, common words like "the," "is," and "and" often appear. A random mix of letters, punctuation, and spaces does not show these patterns. Zipf's law tries to describe this idea using math. In contrast, cryptographers aim to make their secret messages look like random patterns, to avoid repeating parts that might help others break the code.

It is more difficult for cryptographers to handle texts where the amount of repetition and repeated patterns is greater than in normal languages, such as the unknown text in the Voynich manuscript.

Teaching machines to talk nonsense

Scientists have tried to teach machines to create meaningless text. One method used is the Markov chain technique, which uses step-by-step processes and random methods to produce text that appears meaningful. Another method is called the Mad Libs method: it uses templates for different sentence structures and fills in the blanks with groups of words, such as nouns or verbs. These steps can be repeated to create more complex and detailed results. A computer program named Racter used this method to generate nonsense text. However, Racter’s book, The Policeman’s Beard is Half Constructed, was found to have been heavily edited by humans after the program created the initial text.