Language is the most important social product for preserving and passing on culture; and its study can be seen to be an important window on the mind. A natural language is very complicated, yet easy for children to learn. Almost all normal children know a great deal about their language by 3 years old, and most subtle nuances by the time they are 10. Interestingly, people who learn a language when they are very young know subtle properties better than those who learned the language when they were older, and this difference tends not to be overcome with years of speaking.
Language manifests structure at many different levels. The sequences of sounds are limited. The sequences of words are limited, and the same words in different orders mean different things. Dog bites man is a fairly common event, but Man bites dog is newsworthy. The order of man and dog is not the primary cause of the difference because Man is bitten by dog has the same relative order as Man bites dog, but the same logical meaning as Dog bites man.
Language and Communication
Generally it is thought that languages probably evolved
so that people could communicate with one another. Thus the primary function
of a natural human language is communication.
A first approximation of how the process of communication works can begin with a structure originally articulated by C. E. Shannon in 1948 and published as The Mathematical Theory of Communication in 1949. The basic idea is represented in this flow chart:
The source is in some sense the mind of the communicator. It contains the idea or message that is to be communicated. In order for the process to proceed, the message has to be put into a form by which it can be encoded and transmitted. In normal speech this would be putting it into language as a sequence of sound units of speech (phonetics and phonology). These units are put into a sound wave form by the muscles of the lungs, vocal cords, tongue and other articulators. Then the sound waves that are produced go through the air, which is the medium in this case. The ears and brain have to decode the message and put it into a form that can be understood by the mind of the listener at the destination.
Some properties of natural languages
Prior to Chomsky the general view was that the structure of natural languages was too variable and inconsistent to be described in a meaningful way. The logicians thought that if one wanted to communicate precisely he should write in a reformed language more like a first order predicate calculus.
Chomsky argued that natural languages have a rather precise structure with which to represent meanings, it was just that no one studied it correctly. One could think of finding the formal structures that underlie all natural languages.
In 1957 and thereafter Chomsky argued that the productive component of language was its syntax and phonology and semantics were interpretive implementations of the syntax. One could generate an infinite number of sentences by following generative and recursive rules in the syntactic component of the language. This was part of the linguistic competence that all humans either had already, or have the potential to develop. One could discover the rules of language by careful systematic intuitive analyses of different sentences. By 1965 Chomsky seemed to think that there would be many grammars of natural languages in the very near future, following his guidelines. Anderson's analyses of language structure on pages 354-362 are based on a small part of this early work by Chomsky, as are pp 366-367, 374-377, and 379-386.
Chomsky believed that the fact that we know a language means that we somehow have internalized a grammar of that language. It is up to linguists and other cognitive scientists to figure out what the properties of the internalized grammar are. He spent some time discussing the nature of this knowledge.
Chomsky suggested that scientists can construct formal grammars that represent the internal knowledge. He also suggested that there were different levels of constraints on the grammars proposed. The weakest constraint was one that simply had empirical adequacy. Such a grammar would be a formal system by which one could generate all and only the sentences of a language. A second level added structural adequacy to empirical adequacy. This grammar, not only would generate the appropriate sentences, but also would show the appropriate set of structural relations among the units in the grammar. The third level was what Chomsky called theoretical adequacy. This level added to the others the potential to be acquired by humans in the time and data available. Chomsky did not spend much time, himself, on the leearning processes that one might use to acquire a language.
Formally Chomsky defined a language as the set of sentences that are sentences of that language. A grammar of the language is a finite set of rules that generate all and only the sentences of the language. Also, (equivalently?) a grammar could receive any string of concatenated elements and decide whether the string is a sentence in the language or not. People who know a language supposedly have the ability to generate sentences and to evaluate them.
Another for of evidence for the hierarchical nature of language is that some sentences are ambiguous due to mis-parsing of units into the correct higher order units for the communication.
Chomsky proposed that one could begin to generate sentences by an algorithm of sequentially applying sets of rules. The first set of rules were rewrite rules. A rewrite rule might be S--> NP + VP; to be interpreted as rewrite S (for sentence) as NP (noun phrase) concatenated with VP (verb phrase). NP-->D+N; rewrite NP as determiner (the, a, this, etc.) +Noun. VP-->V+NP. Then rewrite D, N, and V as words in the lexicon. D-->the, a; N-->boy, dog; V-->kissed, bit. This little grammar could generate the sentences A dog kissed the boy. The boy bit the dog; and a few others. This grammar seems to capture something about the structure of language, but it obviously needs enhancing. The man is coming home to his wife, shows that the first and second NP cannot be generated totally independently of one another.
Trying to demonstrate the kinds of constraints that a language puts onto the cognitive system that uses it is very informative. One cannot generate a language from left to right or beginning to end. The constraints extend over large regions of the text. The boy who..(whatever)..is coming. One cannot even generate sentences in a hierarchical manner as implied by the phrase structural rules and rewrite rules.
The same basic content can be presented with many different grammatical structures. Chomsky, taking off from his mentor, a man named Zelig Harris, proposed that different sentences with the same set of meaning relations are transformationally related to one another. It is true that speakers can easily generate different forms of the same content, and there is evidence that the closer the formal relationship the faster this can be done. The boy kissed the girl; The girl was kissed by the boy, the one who kissed the girl is the boy; It's the girl that the boy kissed. The boy didn't kiss the girl. Who kissed the girl? Who did the boy kiss?
Once we have the concept of a set of rules that relate one sentence to another as in the examples above, it can be seen that there can be relations between sentence like components within a single sentence; The John met a man who won a gold medal at the Olympics. This sentence contains within a noun phrase the sentence-like clause who won a gold medal at the Olympics.
Other issues in grammar include the fact that many different forms obviously depend upon the particular pragmatic purpose of the communication. These pragmatic constraints make finding a mathematical underpinning of the language that much more difficult to understand psychologically. Even though they may have similar 'cognitive meanings', they have very different implications.
There is behavioral evidence of hierarchical structure including the pause patterns of speakers, where hesitations and errors appear in speech, and even the interesting phenomenon that errors or disfluencies are acceptable and even informative in some sentence locations and not others. If one forgets words when trying to rotely recall a sentence, the grammar predicts where the errors will occur.
It has been proposed that language is an independent modular cognitive system that is encapsulated and basically independent of influence from other cognitive systems of the human organism. It supposedly has its own set of acquisition principles, the principle one being that language acquisition is innate. Recently a theory of parameter setting has been proposed to account for the differences in the forms of different languages. This theory says that we all have all the possible different structural constraints innately present, but they need some inut to be released. The input from our first language sets the parameters. For example, a switch differentiates 'subject-verb-object' order of basic sentences from 'subject-object-verb' order. Another may mark 'pronoun deletion.'
Alternative views argue that language, though it may have some innate components, is generally part of cognition and its properties are not that unique. It is learned to a great extent va the different functions that language plays. There is no real evidence that there is a critical period to language acquisition. Differnt roles that language plays in the environment of children seem to be somewhat correlated with particular acquisitions. Parameter setting seems to be a model which would have many disasterous consequences in bilingual children, or even in learning second languages in general. There is no good evidence that language is encapsulated. Specific environmental inputs affect different aspects of language access.
We have a problem, lots of facts, and no clear explanation.
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