Despite enjoying Lynne Truss's Eats, Shoots & Leaves, I found Crystal's response at least equally enjoyable and useful. Most of the book is a history of linguistic pedantry, beginning all the way back in Ælfric's day when students were threatened with beatings for making inaccurate copies. Crystal uses this history (which reads like selections from Stories of English--not a bad thing) in order to show the utter futility of "protecting" language from change that some have deemed harmful, including the inclusions of new and often foreign words, shortenings/alterations in spelling, complete upsets in pronunciation, and the adoption of new rules for punctuation. These changes were often initially perceived as "errors" or regionalisms (perhaps today we'd call them "slang") but inevitably, when they caught on, these were the new normal.
This is indeed a good point for today's teachers and pedants of all kind to keep in mind: what's "wrong" today may be a matter of course tomorrow. And, it's also worth investigating our motives behind these judgments. Are we, for instance, judging the speech of "outsiders" as "incorrect" when they are speaking with an accent or regional dialect? Also, are we overemphasizing the compliance of nonsensical traditions of writing and speaking that don't actually aid clarity in any way? Crystal picks on the common bugbear, the split infinitive, as well as the pretty dead (hopefully) rule of thumb that you don't end a sentence in a preposition.
In this regard, I was disappointed that Crystal didn't take more risks and point out rules that are at the heart of grammar debates today: singular "they," who/whom, the capitalization of "I," and disappearing apostrophes. I suppose he's writing more than 10 years ago so I can't fault him too much, but these issues didn't start today, and I think most teachers could have seen them coming down the track for a while now.
While I agree with Crystal's thesis--that we should avoid nonsensical pedantry but still teach (some?) grammatical rules in order to foster awareness and greater choice in writing--I do think he very nearly makes Truss a strawman in his argument. Her "zero tolerance" approach is obviously trumped up with hyperbole, but is also a reaction against not caring about grammar and standardization at all, a position that Crystal, as a linguist, obviously shares. He also isn't entirely clear about his overall proposal to teach grammar in schools without all the anxiety of previous ages about doing it "right" or "wrong." Perhaps in Crystal's other books he has less of a rhetorical gloss over these details, but, to me, when teachers say that they don't teacher "grammar" it seems that what they really mean is that they don't teach the traditional vocabulary of grammar (parts of speech, subject/predicate etc), but still do expect and grade on compliance with it. Some go even further to argue that teaching writing should not even touch grammar, but, like Crystal, I think this limits students more than it helps them.
Can we teach grammar awareness without the judgy, my-language-is-better-than-yours, morally-superior attitude? I'm actually not sure. I'll keep trying as an English teacher myself, but I also think there's a good deal of human nature to overcome in doing so--for both teachers and students. People like to be "right" and critique others on very clearly demarcated "rules." It appeals to our sense of fairness, as least in Western culture. We also equate language skill/compliance with intelligence, politeness, and a ton of other social and personal traits. As much as Truss commits these linguistic sins, her popularity also demonstrates that the "language pundit" in all of us hasn't truly "left" and the language-policing attitude will probably continue on for a good while yet, no matter what Crystal says.