Paula, an executive assistant, wrote to ask me to continue the discussion of apostrophes. She wants to know why boss’s has an apostrophe and an s but Chris’ has only an apostrophe.
The truth is that Chris takes just an apostrophe only if you follow the rules in the The Associated Press Stylebook. In other style guides, Chris takes an apostrophe and an s: Chris’s.
"AP" rules that proper names such as Chris, Agnes, and Russ take only an apostrophe, like these examples:
Chris’ photograph appears on page 1 of the business section. (Other style guides use Chris’s.)
Agnes’ banana bread is perfect for breakfast, lunch, and dinner. (Other style guides recommend Agnes’s.)
I do NOT follow AP style, partly because it does not reflect the way we pronounce the names. For instance, I would not say (or write) "Chris’ bread." I would pronounce it "Chris’s bread," wouldn’t you?
I agree with The Microsoft Manual of Style for Technical Publications, which states simply:
Form the possessive of singular nouns and abbreviations by adding an apostrophe and an s. This rule applies even if the noun or abbreviation ends in s.
Among its examples, Microsoft lists "Brooks’s Law."
The Chicago Manual of Style recommends Chris’s, Strauss’s, Inez’s, and Malraux’s. However, it allows Descartes’ and Camus’ (without the additional s) because adding another s could cause mispronunciation.
I do hate to get into all the arcane rules. Keeping it simple is the key to confidence and consistency–especially if you don’t have a shelf full of well-thumbed reference books to turn to.
Here is my rule, Paula, since you asked: Be consistent. Keep it simple. Use manager’s, boss’s, brother’s, Chris’s, Conchita’s, Rich’s, Russ’s, Rex’s, Ira’s, Inez’s, Mr. Jones’s, Ms. Mohammed’s, etc. Don’t create exceptions. And don’t let your Microsoft grammar and spelling checker dissuade you–after all, it tried to shake me from "Brooks’s Law"–Microsoft’s own example!
And if you need to use a word whose possessive form escapes you, rewrite the sentence. For example, is it a writer’s group or a writers’ group? No problem! Just make it a group of writers.