''Colorless green ideas sleep furiously'' is a sentence composed by

Noam Chomsky Avram Noam Chomsky (born December 7, 1928) is an American public intellectual: a linguist, philosopher, cognitive scientist, historian, social critic, and political activist. Sometimes called "the father of modern linguistics", Chomsky is ...

in his 1957 book ''

Syntactic Structures ''Syntactic Structures'' is an influential work in linguistics by American linguist Noam Chomsky, originally published in 1957. It is an elaboration of his teacher Zellig Harris's model of transformational generative grammar. A short monograph ...

'' as an example of a sentence that is

grammatically In linguistics, the grammar of a natural language is its set of structural constraints on speakers' or writers' composition of clauses, phrases, and words. The term can also refer to the study of such constraints, a field that includes domains ...

well-formed, but

semantically Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy, linguistics and comput ...

nonsensical Nonsense is a communication, via speech, writing, or any other symbolic system, that lacks any coherent meaning. Sometimes in ordinary usage, nonsense is synonymous with absurdity or the ridiculous. Many poets, novelists and songwriters have ...

. The sentence was originally used in his 1955 thesis ''

The Logical Structure of Linguistic Theory ''The Logical Structure of Linguistic Theory'' or ''LSLT'' is a major work in linguistics by American linguist Noam Chomsky. It was written in 1955 and published in 1975. In 1955, Chomsky submitted a part of this book as his PhD thesis titled '' ...

'' and in his 1956 paper "Three Models for the Description of Language". There is no obvious understandable meaning that can be derived from it, which demonstrates the distinction between

syntax In linguistics, syntax () is the study of how words and morphemes combine to form larger units such as phrases and sentences. Central concerns of syntax include word order, grammatical relations, hierarchical sentence structure ( constituency) ...

and

semantics Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy Philosophy (f ...

, and the idea that a syntactically well-formed sentence is not guaranteed to be semantically well-formed as well. As an example of a

category mistake A category mistake, or category error, or categorical mistake, or mistake of category, is a semantic or ontological error in which things belonging to a particular category are presented as if they belong to a different category, or, alternativ ...

, it was used to show the inadequacy of certain probabilistic models of grammar, and the need for more structured models.

Senseless but grammatical

Chomsky writes in his 1957 book ''

'': It is fair to assume that neither sentence (1) nor (2) (nor indeed any part of these sentences) has ever occurred in an English discourse. Hence, in any statistical model that accounts for grammaticality, these sentences will be ruled out on identical grounds as equally "remote" from English. Yet (1), though nonsensical, is grammatical, while (2) is not grammatical. Tree Diagram for Chomsky's Sentence

''Colorless green ideas'' – which functions as the subject of the sentence – is an anomalous string for at least two reasons: * The adjective ''colorless'' can be understood as dull, uninteresting, or lacking in color, and so when it combines with the adjective ''green'', this is nonsensical: an object cannot simultaneously lack color and have the color of green. * In the phrase, ''colorless green ideas'' the abstract noun ''idea'' is described as being colorless and green. However, due to its abstract nature, an idea cannot have or lack color. ''Sleep furiously'' – which functions as the

predicate Predicate or predication may refer to: * Predicate (grammar), in linguistics * Predication (philosophy) * several closely related uses in mathematics and formal logic: **Predicate (mathematical logic) **Propositional function **Finitary relation, o ...

of the sentence – is structurally well-formed; in other words, it is grammatical. However the meaning that it expresses is peculiar, as the activity of sleeping is not generally taken to be something that can be done in a furious fashion. Nevertheless, ''sleep furiously'' is both grammatical and interpretable, though its interpretation is unusual. When ''Colorless green ideas'' combines with ''sleep furiously'', this creates a sentence which is felt to be nonsensical by some. On the one hand, an abstract noun like ''idea'' is taken to not have the ability to engage in an activity like sleeping. On the other hand, some think that it is possible for an idea to sleep. Linguists account for unusual nature of this sentence by distinguishing two types of selection: semantic selection ( s-selection) and categorical selection ( c-selection). Relative to s-selection, the sentence is semantically anomalous – senseless – for three reasons: * The s-selection of the adjective ''colorless'' is violated because it can only describe objects that lack color. * The s-selection of the adverb ''furiously'' is violated because it can only describe activity that is compatible with angry action, and such meanings are generally incompatible with the activity of sleeping. * The s-selection of the verb ''sleep'' is violated because it can occur only with subjects that can engage in sleep. However, relative to c-selection, the sentence is structurally well-formed: * The c-selection of the adverb ''furiously'' is satisfied, as it combines with the verb ''sleep'', satisfying the requirement that an adverb modifies a verb. * The c-selection of the adjectives ''colorless'' and ''green'' are satisfied as they combine with noun ''idea'', satisfying the requirement that an adjective modifies a noun. * The c-selection of the intransitive verb ''sleep'' is satisfied as it combines with the subject ''colorless green ideas'', satisfying the requirement that an intransitive verb combines with a subject. This leads to the conclusion that although meaningless, the structural integrity of this sentence is high.

Attempts at meaningful interpretations

Polysemy

The mechanism of

polysemy Polysemy ( or ; ) is the capacity for a sign (e.g. a symbol, a morpheme, a word, or a phrase) to have multiple related meanings. For example, a word can have several word senses. Polysemy is distinct from ''monosemy'', where a word has a singl ...

– where a word has multiple meanings – can be used to create an interpretation for an otherwise non-sensical sentence. For example, the adjectives ''green'' and ''colorless'' both have figurative meanings. ''Green'' has a wide range of figurative meanings, including "immature", "pertaining to environmental consciousness", "newly formed", and "naive". And ''colorless'' can be interpreted as "nondescript". Likewise the verb ''sleep'' can have the figurative meaning of "being in dormant state", and the adverb ''furiously'' can have the figurative meaning "to do an action violently or quickly". * figurative meaning of ''colorless'': nondescript * figurative meanings of ''green'': (i) immature; (ii) pertaining to environmental consciousness; (iii) newly formed; (iv) naive * figurative meaning of ''sleep'': be in a dormant mental state * figurative meaning of ''furiously'': to do an action quickly, vigorously, intensely, energetically or violently When these figurative meanings are taken into account the sentence ''Colorless green ideas sleep furiously'' can have legitimate meaning, with less oblique semantics, and so is compatible with the following interpretations: # ''Colorless green ideas sleep furiously.''= "Nondescript immature ideas have violent nightmares." # ''Colorless green ideas sleep furiously.''= "Naive ideas which have not yet attained their full scope can cause a mind to race even while it attempts to rest"

In popular culture

Chomsky's "colorless green" inspired written works, which all try to create meaning from the semantically meaningless utterance through added context. In 1958, linguist and anthropologist Dell Hymes presented his work to show that nonsense words can develop into something meaningful when in the right sequence. Russian-American linguist and literary theorist

Roman Jakobson Roman Osipovich Jakobson (russian: Рома́н О́сипович Якобсо́н; October 11, 1896Kucera, Henry. 1983. "Roman Jakobson." ''Language: Journal of the Linguistic Society of America'' 59(4): 871–883. – July 18,omeone'shatred never slept, why then, cannot someone's ideas fall into sleep?"

John Hollander John Hollander (October 28, 1929 – August 17, 2013) was an American poet and literary critic. At the time of his death, he was Sterling Professor Emeritus of English at Yale University, having previously taught at Connecticut College, Hunter ...

, an American poet and literary critic, argued that the sentence operates in a vacuum as it is without context. He went on to write a poem based on that idea, entitled ''Coiled Alizarine'' that was included in his book, ''The Night Mirror'' (1971). Years later, Hollander contacted Chomsky about whether the color choice of 'green' was intentional, however Chomsky denied any intentions or influences, especially the hypothesized influence from

Andrew Marvell Andrew Marvell (; 31 March 1621 – 16 August 1678) was an English metaphysical poet, satirist and politician who sat in the House of Commons at various times between 1659 and 1678. During the Commonwealth period he was a colleague and friend ...

's lines from ''

The Garden (poem) "The Garden", by Andrew Marvell Andrew Marvell (; 31 March 1621 – 16 August 1678) was an English metaphysical poet, satirist and politician who sat in the House of Commons at various times between 1659 and 1678. During the Commonwealth pe ...

'' (1681). One of the first writers to have attempted to provide the sentence meaning through context is Chinese linguist

Yuen Ren Chao Yuen Ren Chao (; 3 November 1892 – 25 February 1982), also known as Zhao Yuanren, was a Chinese-American linguist, educator, scholar, poet, and composer, who contributed to the modern study of Chinese phonology and grammar. Chao was born a ...

(1997). Chao's poem, entitled ''Making Sense Out of Nonsense: The Story of My Friend Whose "Colorless Green Ideas Sleep Furiously" (after Noam Chomsky)'' was published in 1971. This poem attempts to explain what "colorless green ideas" are and how they are able to "sleep furiously". Chao interprets "colorless" as plain, "green" as unripened, and "sleep furiously" as putting the ideas to rest; sleeping on them overnight whilst having internal conflict with these ideas. British linguist Angus McIntosh was unable to accept that Chomsky's utterance was entirely meaningless because to him, "colorless green ideas may well sleep furiously". As if to prove that the sentences are in fact meaningful, McIntosh wrote two poems influenced by Chomsky's utterance, one of which was entitled ''Nightmare I''.

Stanford 1985 competition

In 1985, a literary competition was held at

Stanford University Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...

in which the contestants were invited to make Chomsky's sentence meaningful using not more than 100 words of prose or 14 lines of verse. An example entry from the competition, by C. M. Street, is:

Experimental usage

Research has been done by implementing this into conversations on text. Research led by Bruno Galantucci at Yeshiva University has implemented the meaningless sentence into real conversations to test reactions. They ran 30 conversations with 1 male and 1 female slipping "colorless green ideas sleep furiously" eight minutes into the conversation during silence. After the conversation, the experimenters did a post-conversation questionnaire, mainly asking if they thought the conversation was unusual. Galantucci concluded that there was a trend of ''insensitivity'' to conversational coherence. There are two general theories that were garnered from this experiment. The first theory is that people tend to ignore the inconsistency of speech to protect the quality of the conversation. In particular, face-to-face conversation has a 33.33% lower detection rate of nonsensical sentences than online messaging. The authors further explain how humans often disregard some contents of every conversation. The second theory the authors deduced is that effective communication may be subconsciously undermined when dealing with ''conversational'' coherence. These conclusions support the idea that phatic communication plays a key role in social life.

Statistical challenges

Since the 1950s, the field has used techniques more in line with Chomsky's approach. However, this all changed in the mid-1980s, when researchers started to experiment with statistical models, convincing over 90% of the researchers in the field to switch to statistical approaches. In 2000, Fernando Pereira of the

University of Pennsylvania The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universitie ...

fitted a simple statistical Markov model to a body of newspaper text, and showed that under this model, ''Furiously sleep ideas green colorless'' is about 200,000 times less probable than ''Colorless green ideas sleep furiously''. This statistical model defines a similarity metric, whereby sentences which are more like those within a corpus in certain respects are assigned higher values than sentences less alike. Pereira's model assigns an ungrammatical version of the same sentence a lower probability than the syntactically well-formed structure demonstrating that statistical models can identify variations in grammaticality with minimal linguistic assumptions. However, it is not clear that the model assigns every ungrammatical sentence a lower probability than every grammatical sentence. That is, ''colorless green ideas sleep furiously'' may still be statistically more "remote" from English than some ungrammatical sentences. To this, it may be argued that ''no'' current theory of grammar is capable of distinguishing ''all'' grammatical English sentences from ungrammatical ones.

Related and similar examples

In other languages

The French syntactician

Lucien Tesnière Lucien Tesnière (; May 13, 1893 – December 6, 1954) was a prominent and influential French linguist. He was born in Mont-Saint-Aignan on May 13, 1893. As a maître de conférences (senior lecturer) in University of Strasbourg (1924), and l ...

came up with the

French language French ( or ) is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages. French evolved from Gallo-Romance, the Latin spoken in Gaul, and more specifically in Nor ...

sentence "Le silence vertébral indispose la voile licite" ("The vertebral silence indisposes the licit sail"). In Russian schools of linguistics, the ''

glokaya kuzdra ''Glokaya kuzdra'' (russian: Глокая куздра) is a reference to a Russian language phrase constructed from non-existent words in a grammatically proper way, similar to the English language phrases using the pseudoword " gostak". It was s ...

'' example has similar characteristics.

In games

The game of ''

exquisite corpse Exquisite corpse (from the original French term ', literally exquisite cadaver), is a method by which a collection of words or images is collectively assembled. Each collaborator adds to a composition in sequence, either by following a rule (e.g. ...

'' is a method for generating nonsense sentences. It was named after the first sentence generated in the game in 1925: ''Le cadavre exquis boira le vin nouveau'' (the exquisite corpse will drink the new wine). In the popular game of "

Mad Libs Mad Libs is a phrasal template word game created by Leonard Stern and Roger Price. It consists of one player prompting others for a list of words to substitute for blanks in a story before reading aloud. The game is frequently played as a par ...

", a chosen player asks each other player to provide parts of speech without providing any contextual information (e.g., "Give me a proper noun", or "Give me an adjective"), and these words are inserted into pre-composed sentences with a correct grammatical structure, but in which certain words have been omitted. The humor of the game is in the generation of sentences which are grammatical but which are meaningless or have absurd or ambiguous meanings (such as 'loud sharks'). The game also tends to generate humorous

double entendres A double entendre (plural double entendres) is a figure of speech or a particular way of wording that is devised to have a double meaning, of which one is typically obvious, whereas the other often conveys a message that would be too socially a ...

In philosophy

There are likely earlier examples of such sentences, possibly from the philosophy of language literature, but not necessarily uncontroversial ones, given that the focus has been mostly on borderline cases. For example, followers of

logical positivism Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...

hold that "metaphysical" (i.e. not empirically verifiable) statements are simply meaningless; e.g. Rudolf Carnap wrote an article where he argued that almost every sentence from

Heidegger Martin Heidegger (; ; 26 September 188926 May 1976) was a German philosopher who is best known for contributions to phenomenology, hermeneutics, and existentialism. He is among the most important and influential philosophers of the 20th centur ...

was grammatically well-formed, yet meaningless. The philosopher

Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British mathematician, philosopher, logician, and public intellectual. He had a considerable influence on mathematics, logic, set theory, linguistics, ...

used the sentence "Quadruplicity drinks procrastination" in his "An Inquiry into Meaning and Truth" from 1940, to make a similar point; W.V. Quine took issue with him on the grounds that for a sentence to be false is nothing more than for it not to be true; and since quadruplicity doesn't drink ''anything'', the sentence is simply false, not meaningless. Other arguably "meaningless" utterances are ones that make sense, are grammatical, but have no reference to the present state of the world, such as Russell's "The present

King of France France was ruled by monarchs from the establishment of the Kingdom of West Francia in 843 until the end of the Second French Empire in 1870, with several interruptions. Classical French historiography usually regards Clovis I () as the first ...

is bald" (France does not presently have a king) from " On Denoting" (also see

definite description In formal semantics and philosophy of language, a definite description is a denoting phrase in the form of "the X" where X is a noun-phrase or a singular common noun. The definite description is ''proper'' if X applies to a unique individual or o ...

In literature and entertainment

Another approach is to create a syntactically-well-formed, easily parsable sentence using nonsense words; a famous such example is " The gostak distims the doshes".

Lewis Carroll Charles Lutwidge Dodgson (; 27 January 1832 – 14 January 1898), better known by his pen name Lewis Carroll, was an English author, poet and mathematician. His most notable works are ''Alice's Adventures in Wonderland'' (1865) and its sequel ...

Jabberwocky "Jabberwocky" is a nonsense poem written by Lewis Carroll about the killing of a creature named "the Jabberwock". It was included in his 1871 novel ''Through the Looking-Glass'', the sequel to ''Alice's Adventures in Wonderland'' (1865). The bo ...

is also famous for using this technique, although in this case for literary purposes; similar sentences used in neuroscience experiments are called Jabberwocky sentences. In a sketch about linguistics, British comedy duo

Fry and Laurie Fry and Laurie are English comedy double act, mostly active in the 1980s and 1990s. The duo consisted of Stephen Fry and Hugh Laurie, who met in 1980 through mutual friend Emma Thompson while all three attended the University of Cambridge. They ...

used the nonsensical sentence "Hold the newsreader's nose squarely, waiter, or friendly milk will countermand my trousers." The '' Star Trek: The Next Generation'' episode "

Darmok "Darmok" is the 102nd episode of the American science fiction television series '' Star Trek: The Next Generation'', the second episode of the fifth season. Set in the 24th century, the series follows the adventures of the Starfleet crew of the ...

" features a race that communicates entirely by referencing folklore and stories. While the vessel's

universal translator A universal translator is a device common to many science fiction works, especially on television. First described in Murray Leinster's 1945 novella " First Contact", the translator's purpose is to offer an instant translation of any language. A ...

correctly translates the characters and places from these stories, it fails to decipher the intended meaning, leaving Captain Picard unable to understand the alien.

Notes

References

{{Noam Chomsky Semantics Syntax English phrases Noam Chomsky Logic Professional humor 1950s neologisms Nonsense Syntax–semantics interface