Pescriptive rules are conventions

From False Fronts in the Language Wars by Steven Pinker. A very good discussion on the tendency of people to argue strawmen and false dichotomies, in this instance with respect to language.

Nature or nurture. Love it or leave it. If it doesn’t fit, you must acquit.

If you didn’t already know that euphonious dichotomies are usually phony dichotomies, you need only check out the latest round in the supposed clash between “prescriptivist” and “descriptivist” theories of language. This pseudo-controversy, a staple of literary magazines for decades, was ginned up again this month by The New Yorker, which has something of a history with the bogus battle.

[snip]

The thoughtful, nondichotomous position on language depends on a simple insight: Rules of proper usage are tacit conventions. Conventions are unstated agreements within a community to abide by a single way of doing things—not because there is any inherent advantage to the choice, but because there is an advantage to everyone making the same choice. Standardized weights and measures, electrical voltages and cables, computer file formats, the Gregorian calendar, and paper currency are familiar examples.

The conventions of written prose represent a similar kind of standardization. Countless idioms, word senses, and grammatical constructions have been coined and circulated by the universe of English speakers, and linguists capture their regularities in the “descriptive rules”—that is, rules that describe how people speak and understand. A subset of these conventions has become accepted by a virtual community of literate speakers for use in nationwide forums such as government, journalism, literature, business, and academia. These are “prescriptive rules”—rules that prescribe how one ought to speak and write in these forums. Examples include the rules that govern agreement and punctuation as well as fine semantic distinctions between such word pairs as militate and mitigate or credible and credulous. Having such rules is desirable—indeed, indispensable—in many arenas of writing. They lubricate comprehension, reduce misunderstanding, provide a stable platform for the development of style and grace, and credibly signal that a writer has exercised care in crafting a passage.

Once you understand that prescriptive rules are conventions, most of the iptivist controversies evaporate.