Learning a language is certainly different from learning other arts such as walking, playing, swimming etc.It is different in the sense that humans cannot learn their languages only on the basis of the sensory data or input as is possible in other cases.Then how do humans learn their language?Chomsky ,who represents an anthropological approach to linguistics, put forward an interesting theory called UG by which he shows that human brains are preprogrammed or pre-equipped with some tools called LAD to work collaborately with the input and in this way help produce languages.
The argument that prevailed before Chomsky is that language is learnable from the input data only.That is to say the children learn their mother tongue by simple imitation, listening to and repeating what adults say .But Chomskey shows that this cannot be supported for a number of reasons.
He mainly bases his theory on the ’poverty of the stimulus’ argument.
Chomskey and his followers interprete this poverty of the stimulus from various points of view. The common arguments in support of the provery of the stimulus are discussed below.
The poverty of the stimulus implies that the sensory data available from input are insufficient to enable the child to discover certain rules in the language it is learning.
To Chomskey the input is deficient or poor in two ways. At first,it is claimed to be degenerate in the sense that it is marred by performance features ,such as false starts ,slips,fragments,and ungrammatically resulting from those and other pressures inherent in real-time oral communication ,and is therefore an inadequate data base for language learning. For Chomsky, acquiring language cannot be reduced to simply developing an inventory of responses to stimuli, because every sentence that anyone produces can be a totally new combination of words. When we speak, we combine a finite number of elements—the words of our language—to create an infinite number of larger structures—sentences.
Secondly and more serious,however,the input is degenerate in the sense that it does not usually contain ’negative evidence’ ,information from which the learner could work out what is not possible in a given language. Speakers proficient in a language know what expressions are acceptable in their language and what expressions are unacceptable. The key puzzle is how speakers should come to know the restrictions of their language, since expressions which violate those restrictions are not present in the input. This absence of negative evidence—that is, absence of evidence that an expression is part of a class of the ungrammatical sentences in one's language proves that a language is not learnable from input only.There are two kinds of negative evidences such as overt and covert.
Overt negative evidence is unavailable to a child because caretakers react to the truth value,not from,of children’s utterances and rarely correct the ungrammatical speech.Covert negative evidence is also unavailable ,since all that learners hear is grammatical utterances.
In order to understand the negative evidence we can study the following two examples:
For example, in English one cannot relate a question word like 'what' to a predicate within a relative clause (1):
(1) *What did John meet a man who sold?
Such expressions are not available to the language learners, because they are, by hypothesis, ungrammatical for speakers of the local language. Speakers of the local language do not utter such expressions and note that they are unacceptable to language learners.
We can also study the following two sentences to learn about the negative evidence.
1,We gave the book to the girl.
2,We explained the answer to the girl.
Apparently these two sentences have the same surface structures,but whereas (1) contains an indirect object and can be rewritten as (3),
3,We gave the girl the book.
(2) contains a prepositional phrase and cannot be rewritten as (4):
4,We explained the girl the answer.
How does the child find out that ’give’ takes an indirect object and ’explain’ a prepositional phrase?How does the child discover that (4) is ungrammatical?
One possible answer is that the adults correct the children ,but the research does show the different thing.It seems logical to assume ,therefore , that there must be some innate principle which prevents the child from producing sentences like (4).
Universal grammar offers the solution to the poverty of the stimulus problem by saying that there are certain principles and parameters ,which are inherent in a child.And a child learns his language with the help of these principles.In Chomsky’s view, the reason that children so easily master the complex operations of language is that they have innate knowledge of certain principles that guide them in developing the grammar of their language. In other words, Chomsky’s theory is that language learning is facilitated by a predisposition that our brains have for certain structures of language.
But the principles and parameters are not itself sufficient to create language.They have to be ’triggered ’ by something in the language input the child hears.This is seen predominantly as caused by positive evidence-things that actually present in the input.So,the word order parameters for English(SVO) may be triggered by hearing sentence such ’Lucy reads a book”.The role of language input is therefore to trigger the appropriate setting for each parameter.So,the setting for the parameters is a must.There might be no initial setting, so a child who begins to learn a language can adopt any setting with equal ease.Or there might be a default seting consisting of one or other of the possible settings.Two possible settings are non-pro-drop and pro-drop settings.
Some other evidences which support the idea that a language cannot be learnt from input only are as follows.
1,Even before the age of 5, children can, without having had any formal instruction, consistently produce and interpret sentences that they have never encountered before. It is this extraordinary ability to use language despite having had only very partial exposure to the allowable syntactic variants is another proof that the language cannot be learnt from the input data only.
2,For Chomsky’s theory to hold true, all of the languages in the world must share certain structural properties. And indeed, Chomsky and other generative linguists like him have shown that the 5000 to 6000 languages in the world, despite their very different grammars, do share a set of syntactic rules and principles. These linguists believe that this “universal grammar” is innate and is embedded somewhere in the neuronal circuitry of the human brain. And that would be why children can select, from all the sentences that come to their minds, only those that conform to a “deep structure” encoded in the brain’s circuits.
3,Thus, from birth, children would appear to have certain linguistic abilities that predispose them not only to acquire a complex language, but even to create one from whole cloth if the situation requires. One example of such a situation dates back to the time of plantations and slavery. On many plantations, the slaves came from many different places and so had different mother tongues. They therefore developed what are known as pidgin languages to communicate with one another. Pidgin languages are not languages in the true sense, because they employ words so chaotically—there is tremendous variation in word order, and very little grammar. But these slaves’ children, though exposed to these pidgins at the age when children normally acquire their first language, were not content to merely imitate them. Instead, the children spontaneously introduced grammatical complexity into their speech, thus in the space of one generation creating new languages, known as creoles.