They put grammatical rules for English into three categories:
1. Real Rules – these are rules that do matter and must be followed. They are the rules that make English English (e.g. articles precede nouns).
2. Social Rules – these are rules that separate standard usage from nonstandard usage. Schooled writers follow these naturally. Only those for whom English is not their first language have to think about these.
3. Invented Rules – these are rules that grammarians have created which they think we should follow. Most of these date from the last half of the eighteenth century. A good example of these kinds of rules is the “split infinitive”.
Williams and Colomb’s advocate a careful, but balanced approach to the invented rules. They write with some irony,
But if you try to obey all the rules all the time, you risk becoming so obsessed with rules that you tie yourself in knots. And sooner or later, you will impose those rules—real or not—on others. After all, what good is learning a rule if all you can do is obey it? The alternative to blind obedience is selective observance. But you then have to decide which rules to observe and which to ignore (14).So which rules should you follow and which can you ignore? It goes without saying that Real Rules must be followed and that Social Rules will usually be obeyed out of habit. But when it comes to Invented Rules, selective use is recommended.
What then should be the overarching concern when it comes to grammatical rules if it is not to be a scrupulous rule keeper? The primary concern should to be your audience. Some audiences expect a more elegant sophisticated style of writing, while others a more straightforward style. For the former, paying attention to Invented Rules that have come to represent a more elegant style will win over your audience. This list of rules includes:
1. Don’t split infinitives.I think what this lesson is driving at is that what we should be aiming for in our writing is not correctness but clarity. And if we can throw in a little grace and elegance all the better.
2. Use whom as the object of a verb or preposition.
3. Don’t end a sentence with a preposition.
4. Use the singular with none and any.
See first post: Writing Style 1