Grammar pedants miss the point

The BBC has an article by Steven Pinker, extracted from Steven Pinker’s The Sense of Style: The Thinking Person’s Guide to Writing in the 21st Century, about grammar:

Many people have strong opinions on the quality of language today. They write books and articles deploring it, fire off letters to the editor, and call in to radio talk shows with their criticisms and complaints. Their concern is correct usage, the rules of proper English such as these: the word less may not be used for countable items; a modifier may not contain a dangling participle; the verb aggravate does not mean ‘annoy’, it means ‘make worse’.
It’s not hard to see how these worries arose. There is a kind of writer who makes issues of usage impossible to ignore. These writers are incurious about the logic and history of the English language and the ways in which it has been used by its exemplary stylists. They have a tin ear for its nuances of meaning and emphasis. Too lazy to crack open a dictionary, they are led by gut feeling and intuition rather than attention to careful scholarship. For these writers, language is not a vehicle for clarity and grace but a way to signal their membership in a social clique.
Who are these writers? You might think I’m referring to twittering teenagers or Facebooking freshmen. But the writers I have in mind are the purists, also known as sticklers, pedants, peevers, snobs, snoots, nit-pickers, traditionalists, language police, usage nannies, grammar Nazis and the Gotcha! Gang. In their zeal to purify usage and safeguard the language, they have made it difficult to think clearly about felicity in expression, and have muddied the task of explaining the art of writing.
Many purists maintain that the only correct sense of a word is the original one. That’s why they insist, for example, that transpire can only mean ‘become known’, not ‘take place’ (since it initially meant ‘release vapor’, from the Latin spirare, ‘to breathe’), and that decimate can only mean ‘killing one in ten’ (since it originally described the execution of every tenth soldier in a mutinous Roman legion).
The misconception is so common that it has been given a name: the etymological fallacy. It can be debunked with a glance at any page of a historical reference book, such as the Oxford English Dictionary, which will show that very few words retain their original senses. Deprecate used to mean ‘ward off by prayer’, meticulous once meant ‘timid’, and silly went from ‘blessed’ to ‘pious’ to ‘innocent’ to ‘pitiable’ to ‘feeble’ to today’s ‘foolish’. And as Kory Stamper, an editor at the Merriam-Webster Dictionary, has pointed out, if you insist that decimate be used only with its original meaning, ‘kill one in ten’, shouldn’t you also insist that December be used with its original meaning: ‘the tenth month in the calendar’?
The last refuge of the stickler is the claim that proper usages are more logical than the alternatives. But this claim gets it backwards. Many of the commonest usage errors are the result of writers thinking logically, when they should be mindlessly conforming to convention. Writers who spell lose as loose (which would make it follow the pattern in choose), who punctuate the possessive of it as it’s (just as we punctuate the possessive of Pat as Pat’s), or who use enormity to mean “the quality of being enormous” (just as we use hilarity to mean the quality of being hilarious) are not being illogical. They are being too logical, while betraying their lack of familiarity with the conventions of the printed page. This may be grounds for suspicion by the reader and a prod to self- improvement for the writer, but it is not a failure of consistency or logic.
When a not-so-careful writer tries to gussy up his prose with an upmarket word that he mistakenly thinks is a synonym of a common one, like simplistic for simple or fulsome for full, his readers are likely to conclude the worst: that he has paid little attention to what he has read, is affecting an air of sophistication on the cheap, and is polluting a common resource. The preferred sense of disinterested as ‘impartial’, for example, has coexisted for centuries with its frowned-upon sense as ‘bored’. This should not be all that surprising, because many words embrace happily coexisting senses, such as literate, which means both ‘able to read’ and ‘familiar with literature’, and religious, which means both ‘pertaining to religion’ and ‘obsessively thorough’. The senses are usually sorted out by the context, so both survive. A language has plenty of room for multiple meanings, including the ones that good writers hope to preserve.
Though correct usage is well worth pursuing, we have to keep it in perspective. Yes, writers today sometimes make unfortunate choices. But so did the writers of yesterday and the day before, while many of the kids today, the target of so much purist bile, write gorgeous prose, comment incisively on usage and even develop their own forms of purism (such as the Typo Eradication Advancement League, which stealthily corrects grocers’ signs with correction fluid and felt markers).
For all the vitriol brought out by matters of correct usage, they are the smallest part of good writing. They pale in importance behind coherence, classic style, and overcoming the curse of knowledge, to say nothing of standards of intellectual conscientiousness. If you really want to improve the quality of your writing, or if you want to thunder about sins in the writing of others, the principles you should worry about the most are not the ones that govern fused participles and possessive antecedents, but the ones that govern critical thinking and factual diligence.
We can share our advice on how to write well without treating people in need of it with contempt. We can try to remedy shortcomings in writing without bemoaning the degeneration of the language. And we can remind ourselves of the reasons to strive for good style: to enhance the spread of ideas, to exemplify attention to detail and to add to the beauty of the world.

Rico says don't get him started; he's still fulminating about the difference between 'further' and 'farther' in the damned Ford ads...