The Sense of Style: The Thinking Person's Guide to Writing in the 21st Century

by Steven Pinker

And this brings us to the reasons to obey some prescriptive rules (the ones accepted by good writers, as opposed to the phony ones that good writers have always ignored). One is to provide grounds for confidence that the writer has a history of reading edited English and has given it his full attention. Another is to enforce grammatical consistency: to implement rules, such as agreement, that everyone respects but that may be hard to keep track of when the sentence gets complicated (see chapter 4). The use of consistent grammar reassures a reader that the writer has exercised care in constructing his prose, which in turn increases her confidence that he has exercised care in the research and thinking behind the prose. It is also an act of courtesy, because consistent trees are easier to parse and harder to misunderstand.