As any regular reader of this column can tell you, possessives aren’t as hard as they seem. Usually, if you just take it slow and remember the rules, you can avoid mistakes like “the Smith’s house” and “Charle’s mother” when you mean “the Smiths’ house” and “Charles’ mother” or the also-correct “Charles’s mother.”
Learn the rules, apply the rules and you’re home free.
But that’s not the end of the story. I just run out of space before I can get to the ugly truth: Special rules and exceptions further complicate the already difficult business of possessives.
These special situations turn the basic rules upside-down, telling us that a seeming possessive like “teachers college” might not take an apostrophe at all.
They tell us that that both “Ben and Lisa’s cars” and “Ben’s and Lisa’s cars” are correct. And they tell us that a singular, like “conscience,” runs contrary to simple possessive rules in “conscience’ sake.”
Here are some special rules you should know if you want to fully master possessives.
Shared possessives. If you had to write about cars owned by Ben and Lisa, which form would you choose: Ben and Lisa’s cars or Ben’s and Lisa’s cars? Don’t answer that until you know who owns which car. If Ben and Lisa own the cars together, for example, if they’re married, you’d write Ben and Lisa’s cars.
If Ben and Lisa are just friends, each of whom owns a car, you’re talking about Ben’s and Lisa’s cars. Here’s a device to remember this: If the parties share ownership, they must also share a single apostrophe-plus-S. If they own the things separately, they each get their own apostrophe and S.
“Sake” expressions. Normally, a word like “conscience” is easy to form into a possessive. Just add apostrophe and S: My conscience’s incessant nagging.
But when you put “sake” after it, you run into a situation the Associated Press Stylebook considers a problem: so many S sounds. That’s why, in these “sake” expressions, AP says to throw out the normal rules on possessives that say to add an S after the apostrophe.
Instead, use just the apostrophe: It’s “conscience’ sake” even though in every other circumstance you’d add an S after that apostrophe. “Goodness’ sake” ups the ante. Here, it’s easy to see what a mess you’d get with four Ss in a row: goodness’s sake. If you’re following AP, always leave the possessive S off a word like goodness or conscience if it comes before “sake.”
Descriptive terms. In farmers market/farmers’ market, what’s the relationship of the farmers to the market? Do they collectively own it, making the term possessive: farmers’ market? Or are the farmers just the defining characteristic of this particular kind of market, making farmers more like an adjective than a possessor: farmers market?
The answer: Either interpretation is correct. You can think of it as their market, or you can think of the market as merely featuring them the way a shoe store features shoes. This is why you may see it written either way in a credible and well-edited publication.
AP has an interesting way of breaking this down: “The apostrophe usually is not used if ‘for’ or ‘by,’ rather than ‘of,’ would be appropriate in the longer form.” For example, in AP’s estimation, a radio band for citizens is a citizens band radio.
A college for teachers is a teachers college. A guide for writers is a writers guide. But you can’t do this if the first word is “children” or “people” or another plural that does not end in S because it’s just too weird to say “children hospital” or “people republic.” So disregard that “for” and “of” business in these cases and just write “children’s hospital” and “people’s republic.”