I often read Wilson Follett’s Modern American Usage: A Guide, both as a guide to good writing and as a source of wisdom. It is also an antidote to Language Log, whose contributors often (mostly?) deride prescriptivism in language.
When I read Follett’s book for its wisdom, I open it randomly. Recent explorations have led me to these passages:
It is … one of the striking features of the libertarian position [with respect to language] that it preaches an unbuttoned grammar in a prose style that is fashioned with the utmost grammatical rigor. H.L. Mencken’s two thousand pages on the vagaries of the American language are written in the fastidious syntax of a precisian. If we go by what these men do instead of by what they say, we conclude that they all believe in conventional grammar, practice it against their own preaching, and continue to cultivate the elegance they despise in theory….
[T]he artist and the user of language for practical ends share an obligation to preserve against confusion and dissipation the powers that over the centuries the mother tongue has acquired. It is a duty to maintain the continuity of speech that makes the thought of our ancestors easily understood, to conquer Babel every day against the illiterate and the heedless, and to resist the pernicious and lulling dogma that in language … whatever is is right and doing nothing is for the best. [pp. 30-31]
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IThis book] accept[s] the long-established conventions of prescriptive grammar … on the theory that freedom from confusion is more desirable than freedom from rule…. [p. 243]