What is meant by prescriptive and descriptive approach to language.

Descriptive approach to language: tries to explain things as they actually are, not as we wish them to be, tries to find the unconscious rules that people follow when they are speaking and writing. Describes our basic linguistic knowledge.
Prescriptive approach to language: tries to tell us how one should speak and write and what rules of language usage people should know.
Prescription can only occur after the language has been described, good prescription depends on an adequate description.
Prescriptivists accuse descriptivists of being anarchists who want to do away with all the rules of language.
Descriptivists accuse prescriptivists of uniformed bigotry.
Descriptive linguistics is the work of analyzing and describing how language is (or was) spoken by a group of people in a speech community. All scholary research in linguistics is descriptive, it aims to observe the linguistics world as it is, without the bias of preconceived ideas about how it ought to be. [for teaching]
Prescription can refer to both codification and enforcement of rules governing how a language is to be used. These rules can cover such topics as standards for spelling, grammar or syntax , or rules of what is deemed socially and politically correct. It includes the mechanisms for establishing and maintaining an interregional language or standarised spelling systems.

*Prescriptive: A set of rules and examples dealing with the syntax and word structures of a language, usually intended as an aid to the learning of that language. Prescriptive grammar refers to the structure of a language as certain people think it should be used. A prescriptive grammar is an account of a language that sets out rules (prescriptions) for how it should be used and for what should not be used (proscriptions), based on norms derived from a particular model of grammar.
For English, such a grammar may prescribe ‘I’ as in ‘It is I’ and proscribe me as in ‘It's me’. It may proscribe ‘like’ used as a conjunction, as in ‘He behaved like he was in charge’, prescribing instead ‘He behaved as if he were in charge’. Prescriptive grammars have been criticised for not taking account of language change and stylistic variation, and for imposing the norms of some groups on all users of a language. They have been discussed by linguists as exemplifying specific attitudes to language and usage.
* Descriptive: The systematic study and description of a language. Seeks to describe how it is used objectively, accurately, systematically, and comprehensively. Descriptive grammar refers to the structure of a language as it is actually used by speakers and writers.



Prescription can only occur after the language has been described, good prescription depends on adequate description.
Both kinds of grammar are concerned with rules-but in different ways.
Specialists in descriptive grammar (called linguists) study the rules or patterns that underlie our use of words, phrases, clauses, and sentences. They aim to observe the linguistic world as it is without the bias of preconceived ideas of how it ought to be. On the other hand, prescriptive grammarians (such as most editors and teachers) lay out rules about what they believe to be the “correct” or “incorrect” use of language.
They codify and enforce the rules that should govern the language.

Robert Lowth (November 27, 1710 – November 3, 1787) was a Bishop of the Church of England, a professor of poetry at Oxford University and the author of one of the most influential textbooks of English grammar.

Lowth is also remembered for his publication in 1762 of A Short Introduction to English Grammar. Prompted by the absence of simple and pedagogical grammar textbooks in his day, Lowth set out to remedy the situation.
Lowth's grammar is the source of many of the prescriptive shibboleths (haslo rozpoznawcze) that are studied in schools, and established him as the first of a long line of usage commentators who judge the English language in addition to describing it.
An example of both is one of his footnotes: "Whose is by some authors made the Possessive Case of which, and applied to things as well as persons; I think, improperly."
His most famous contribution to the study of grammar may have been his tentative suggestion that sentences ending with a preposition—such as "what did you ask for?"—are inappropriate in formal writing. In what may have been intentional self-reference, Lowth used that very construction in discussing it. "This is an Idiom which our language is strongly inclined to; it prevails in common conversation, and suits very well with the familiar style in writing; but the placing of the Preposition before the Relative is more graceful, as well as more perspicuous; and agrees much better with the solemn and elevated Style."

Lowth's method included criticising "false syntax"; his examples of false syntax were culled from Shakespeare, the King James Bible, John Donne, John Milton, Jonathan Swift, Alexander Pope, and other famous writers, raising the question, by what authority did Lowth aspire to judge these writers' syntax? His understanding of grammar, like that of all linguists of his period, was based largely on the study of Latin, and a number of his judgments were arrived at by applying Latin grammar to English, a misapplication according to critics of a later generation (and his own stated principles; he condemned "forcing the English under the rules of a foreign Language").
Thus Lowth condemns Addison's sentence "Who should I meet the other night, but my old friend?" on the grounds that the thing acted upon should be in the "Objective Case" (corresponding, as he says earlier, to an oblique case in Latin), rather than taking this example and others as evidence from noted writers that "who" can refer to direct objects.

Lowth's ipse dixits appealed to those who wished for certainty and authority in their language. Lowth's grammar was not written for children; however, within a decade after it appeared, versions of it adapted for the use of schools had appeared, and Lowth's stylistic opinions acquired the force of law in the schoolroom. The textbook remained in standard usage throughout educational institutions until the early 20th century.


Robert Lowth, Short Introduction to English Grammar
“Lowth was a philologist ‘more inclined to melancholy than to mirth’, who believed that Hebrew was spoken in paradise. His Short Introduction to English Grammar (1762) became a standard text-book, and his name has become synonymous with prescriptive grammar. Lowth’s reputation as a prescriptivist is not entirely deserved. Though he liberally illustrated his grammar rules with errors to be found in the English Bible and in standard authors, his approach to correctness was not invariably rigid and, like most grammarians, he described English as well as prescribing its rules. . . . Lowth was convinced that English is rule-governed, and he defended the regularity and simplicity of the language against a tradition which viewed it as too primitive to possess any grammar at all. His model was Latin grammar, but he readily modified this to accommodate the idiosyncrasies of English.”

Joseph Priestley.
Joseph Priestley, A Course of Lectures on the Theory of Language and Universal Grammar

The Rudiments of English Grammar (1761) was a popular English grammar textbook written by the eighteenth-century British polymath Joseph Priestley(March 26, 1733 – February 8, 1804) was an eighteenth-century British natural philosopher, Dissenting clergyman, political theorist, theologian, and educator).

While a minister for a congregation in Nantwich, Cheshire, Priestley established a local school; it was his first successful educational venture. Believing that all students should have a good grasp of the English language and its grammar before learning any other language and dismayed at the quality of the instruction manuals available, Priestley wrote his own textbook: The Rudiments of English Grammar (1761).
The book was very successful—it was reprinted for over fifty years. Its humour may have contributed to its popularity; for example, Priestley illustrated the couplet with this rhyme:

Beneath this stone my wife doth lie:
She's now at rest, and so am I.

Priestley's innovations in the teaching and description of English grammar, particularly his efforts to disassociate it from Latin grammar, made his textbook revolutionary and have led twentieth-century scholars to describe him as "one of the great grammarians of his time."
Rudiments influenced all of the major British grammarians of the late eighteenth century: Robert Lowth, James Harris, John Horne Tooke and even the American Noah Webster.

Early Grammarians (18th Century)
A proposal for an Academy of the English Language was first brought forth by Jonathan Swift in 1712, but the Parliament voted against it. Nevertheless, several grammarians wrote dictionaries and grammar books in a prescriptive manner - telling people what to do or not to do with the language. Samuel Johnson's A Dictionary of the English Language was published in 1755 and Robert Lowth's Introduction to English Grammar appeared in 1762.
Early grammarians felt that language should be logical, therefore, the double negative was considered incorrect (two negatives equal one positive) and should not be used.
They also didn't like shortened or redundant words, borrowing words from other languages (except Latin and Greek), split infinitives, or prepositions at the end of the sentence.

A more scientifically minded attitude took hold by the 19th century when the Oxford English Dictionary was proposed in 1859. It was to be a factual account of every word in the English language since 1000 including its main form, pronunciation, spelling variations, part of speech, etymology, meanings in chronological order and illustrative quotations. The project was begun in 1879 under its first editor, James AH Murray. The1st edition was published in 1928, with supplements in 1933 and 1972-6. The second edition was published in 1989 and it recognised American and Australian English, as the International Phonetic Alphabet for pronunciation.

Abstract:
Joseph Priestley's (1733-1804) Rudiments of English Grammar (1761, second revised edition 1768) has often been interpreted as demonstrating that, unlike most 18th-century grammarians, Priestley took a descriptive approach towards the study of language. This article argues that such a characterisation both of Priestley's work and that of his contemporaries is misleading. The article offers a reappraisal of Priestley's Grammar, demonstrating that the idea of linguistic perfectibility is central to his linguistic ideas, but that it has often been overlooked by modern commentators. The two editions of Priestley's Grammar are assessed, and it is argued that the substantial alterations that he makes for the second edition reveal a grammarian struggling to bring order to the study of the English language.