Descriptive Grammar and Prescriptive Grammar

In our Glossary of Grammatical and Rhetorical Terms, you’ll find two definitions of grammar:

1. The systematic study and description of a language.

2. 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.

Descriptive grammar (definition #1) refers to the structure of a language as it's actually used by speakers and writers.

Prescriptive grammar (definition #2) refers to the structure of a language as certain people think it should be used.

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. 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. (See What Is a SNOOT?)

Interfacing With Grammar

To illustrate these different approaches, let's consider the word interface. The descriptive grammarian would note, among other things, that the word is made up of a common prefix (inter-) and a root word (face) and that it’s currently used as both a noun and a verb. The prescriptive grammarian, however, would be more interested in deciding whether or not it is “correct” to use interface as a verb.

Here's how the prescriptive Usage Panel at The American Heritage Dictionary passes judgment on interface:

The Usage Panel has been unable to muster much enthusiasm for the verb. Thirty-seven percent of Panelists accept it when it designates the interaction between people in the sentence The managing editor must interface with a variety of freelance editors and proofreaders. But the percentage drops to 22 when the interaction is between a corporation and the public or between various communities in a city. Many Panelists complain that interface is pretentious and jargony.

Similarly, Bryan A. Garner, author of The Oxford Dictionary of American Usage and Style, dismisses interface as "jargonmongers' talk."

By their nature, all popular style and usage guides are prescriptive, though to varying degrees: some are fairly tolerant of deviations from standard English; others can be downright cranky. The most irascible critics are sometimes called "the Grammar Police."

Though certainly different in their approaches to language, both kinds of grammar--descriptive and prescriptive--are useful to students.