Kenneth G. Wilson (1923). The Columbia Guide to Standard American English. 1993.
PRESCRIPTIVE AND DESCRIPTIVE GRAMMAR AND USAGE
For the past half-century, these terms have served as useful labels for two contrasting approaches to the study of grammar and usage and especially to the teaching of these matters. They have also long served as epithets in the recurrent name-calling that quarreling over correctness, appropriateness, and permissiveness in language seems to elicit.
The terms represent polar values: (1) A descriptive approach to language describes in full detail precisely how we use that language. The chief values of this approach are accuracy and an unretouched picture of usage, warts and all. (2) A prescriptive approach insists that however many variables might be found, there are better and worse choices; it will specify at least which is most appropriate, more likely which is acceptable, or, in its most rigorous application, which is correct. Clearly, the prescriptive approach is easier to teachthere is always one right answer; the descriptive approach may offer several possible answers, each appropriate in one or another context.
This book uses both approaches. Users are seeking help, and they should find it. The problem is that a simplistic correct answer may seem helpful, but often when it appears to contradict users experience, they will either shrug off the prescription or find themselves unable to accept it. For example: to say succinctly that irregardless is not a word or at least that it ought to be treated as though it were not a word, is prescriptive. The rule being promulgated is: Dont use irregardless; pretend it doesnt exist, because, in fact, its not in Standard English.
But, in fact, thats not true. It is a word, and therefore it is in the dictionaries; many people use it, including some who in other respects speak Standard English. A descriptive account of the word will show who uses it and when, where, and why. Irregardless, it turns out, occurs regularly in Common and Vulgar English, but in Standard its only acceptable use is jocular. A descriptive account will end by pointing out that the inadvertent use of irregardless in Standard English can be a shibboleth.
The prescriptive commentator then impatiently inquires, Why all the fuss? Why pussyfoot about? Just tell the world not to use irregardlessthats simple, sound, and teachable. The descriptive commentator will offer at least two objections: (1) The word may be Substandard now, but you cant be sure it wont change in status. In fact it may be in the process of such change even now: it may be fading to an obsolete status (in which case we can stop talking about it), or it may someday become Standard. (2) Even more important, sometimes Standard speakers do use irregardless; the issue is where and how.
Even in spelling and pronunciation, where prescription may seem less problematic, description may sometimes be more nearly accurate. Prescription says judgment is the correct spelling, but description accurately points out that even Edited English considers judgement correct too. And although the teacher may prescribe DEK-uh-dent as the correct way to say decadent, the student will discover other teachers who say (also in Standard English) dee-KAI-dent.
This book, as it must, uses both approaches, depending on the problem. See the entry on RULES AND GENERALIZATIONS for an account of the aptness of each approach to particular kinds of questions: Where real rules apply, prescription is the way to go. But much of grammar and most of usage require generalizations rather than rules, because what so often we must provide is some current best advice on a problem that is undergoing change even as we discuss it. Description faces up to complexity and raggedness and avoids simplistic glossing over of existing variation in pronunciations, forms, or meanings. Rigorous prescribers often charge describers with being permissive, and the countercharge of describers is that prescribers are simplistic, peddling half-truths and lies as though they were true. But in the end, a guide to usage must give advice, and so this manual prescribes for its users when it can. The difference is that it also explains such other experiences as users are likely to encounter and where possible explains what they mean. See also CONSERVATIVES IN LANGUAGE MATTERS; CONSERVATIVE USAGE; LIBERALS IN LANGUAGE MATTERS; LIBERAL USAGE; PURISTS.