Descriptive & Prescriptive Grammar

Grammar describes the native speaker’s competence in his/her language. Grammars can be descriptive or prescriptive. Is the former more useful than the latter? Explain your answer by discussing the merits of the two approaches in your capacity as a speaker or teacher of English.

To me as a speaker of the English language, both descriptive and prescriptive grammars are useful.
Descriptive grammar generally advises us not to be overly concerned with matters of correctness; language they say, is not good or bad; it simply is. As the English language is a living system of communication, within a generation or two, words and phrases come into fashion and fall out again. Over centuries, word endings and entire sentence structures can change or disappear.
Descriptive grammar is different from prescriptive grammar in that descriptive rules are never taught to native speakers of a language and often do not correspond to the prescriptive rules taught at schools. Hence, there may be differences from style to style and dialect to dialect.
Descriptive rules allow for different varieties of a language; and accept the patterns a speaker actually uses and tries to account for them as long as consistency is maintained and accepted by his community. As such, in descriptive grammar, the rules are less organised and informal. As such, a native speaker can just speak his mind without worrying about whether the language used is bad or good, so long as the message intended for the receiver is achieved.
Prescriptive grammar on the other hand deals with what the grammarian believes to be right and wrong; good or bad language use. Prescriptive rules of grammar prescribe a standard of usage and this standard English, a sociolinguist would term as high language.
Prescriptive grammar has specific rules which serve to mould spoken and written English to some standard form. Thus, prescriptive rules are taught in schools by teachers to students in the standard form of English. This form is also known as formal English which is used in academic writing, and when a speaker gives a speech to an audience, or a lecturer lectures his class. When a speaker of the English language wants to speak politely or very carefully to another, he also needs to use this standard form.
Prescriptive grammar have rules that strict grammarians have laid out for English speakers to follow and without a doubt, there are many. Prescriptive rules emphasise correctness in sentence structures, past and present tenses etc.
Some examples of prescriptive rules are: a) ‘’Shall” to be used for first person (“I” or “we”). We use “will” with second or third persons (“you”, “he”, “she”, “it” and “they”).
RIGHT: I shall be home tomorrow
WRONG: I will be home tomorrow b) Never use “not” with “hardly, scarcely, neither, never, none, no one, nobody or nothing” as these words when combined, will form a double negative, which is incorrect in English.
RIGHT: I can hardly learn to sew
WRONG: I can’t hardly learn to sew c) Never end a sentence with a preposition.
RIGHT: From where did Miss Lim come?
WRONG: Where did Miss Lim come from?
Prescriptive and descriptive grammars are often seen as opposites, in the sense that one declares how language should be while the other declares how language is. But they can also be complementary, and usually exist in dynamic tension. Many commentators on language show elements of both prescriptive and descriptive in their thinking, and popular debate on language issues frequently revolves around the question of how to balance these.