Diagrammaticality...huh?

So, I'm taking a course on the use of modern grammar and, after the first day, I can tell it's going to be fairly intense. I've already had to read a lot about the history of grammar and ideas about linguistics, etc. Mostly drab stuff, right? Right. However, I did come across a bit of information in one of the essays presented in the book Language Alive in the Classroom. This particular essay was written by Edwin Battistella. In it, he comments on an issue that I have heard raised on more than one occasion, and that is the relevance of grammar. He writes:

The fact that students are anxious about grammar suggests that they will be attentive to the question of grammatical correctness, and there is a fairly extensive body of literature on how and whether grammar should be taught. Turning students' concerns about grammar into a teachable moment has some risks, of course: it is easy to be misunderstood in a classroom, and when students are told that traditional grammar is inadequate and that no varieties of language are linguistically right or wrong, they may hear that grammar does not matter.

Grammar does not matter. Have you heard this proclamation lately? It's absurd. Grammar is not a full, firm set of rules that constitute a language. That's the misconception we're seeing today. Grammar is descriptive of a language. Just as language grows and changes, so should the grammar describing it. Of course, there ARE rules. Without them, language could very well run rampant and it would all be foreign, but I think people approach grammar in the wrong way. Grammar should comment on the appropriateness of the use of language in different settings, not dictate an absolute right and absolute wrong.

But those are just my thoughts.