thinking about good usage

I came across this statement in the Chicago Manual of Style:

While common usage can excuse many slipshod expressions, the standards of good usage make demands on writers and editors. Even so, good usage should make only reasonable demands without setting outlandishly high standards.

They precede this by pointing out that dictionaries describe how language is used, and that “despite occasional usage notes,” their job is to be descriptive, not prescriptive.

I am a big fan of the American Heritage Dictionary and its usage notes, but the AHD is not holy writ. In his book The Sense of Style, Steven Pinker says: “When I asked the editor of the [American Heritage Dictionary] how he and his colleagues decide what goes into it, he replied, ‘We pay attention to the way people use language.’”

It’s good to have reference works like the Chicago Manual of Style to keep us on the straight and narrow with their reasonable demands.