Would you write “the Perkins’ dog” or “the Perkins’s dog”?
I don’t know about you, but I’m often confused by the use of plurals and possessive apostrophes in words that end in an “s” sound. Should we put just an apostrophe after the existing “s” or should we add both an apostrophe and another “s”?
Of course, I’m not sure that an awful lot of people would be able to correct us if we were wrong. After reviewing guidelines for plurals in three separate reference books, there doesn’t appear to be a consensus on the tough calls. But still it’s nice to at least have a rule-of-thumb, if for no other reason than to improve our power writing skills.
Let’s start by reviewing possessive apostrophes with singular nouns that do not end in “s”. In that case, the possessive plurals rule is quite simple: add an apostrophe and an “s”, as in John’s house or May’s book.
Similarly, you can add just an apostrophe to most plural nouns, as in the players’ box and the dogs’ bones.
Where I get into troubled waters is adding the possessive to proper nouns (i.e. names and titles) that end in a sibilant. As the Chicago Manual of Style wryly puts it, “How to form the possessive of polysyllabic personal names ending with the sound of “s” or “z” probably occasions more dissension among writers and editors than any other orthographic matter open to disagreement.” Sounds confusing, but it simply means this issue of possessive plurals is the most controversial one faced by writers and editors.
Personally, I like the way the Gregg Reference Manual treats the subject. It recommends a pronunciation-based approach. If you would add an extra syllable when saying the word, add both an apostrophe and an “s” — if you would not add an extra syllable, simply use the apostrophe. It cites the following example, “Mr. Perkins’s kindness” (if you pronounce the name in three syllables) or “Mr. Perkins’ kindness” (pronouncing the name in two syllables).
To use another example, let’s consider Mr. Perkins’ dog (where I would normally pronounce Perkins as two syllables). On the other hand, if the Perkins families were having a reunion, I might write the Perkins’s reunion (where I would normally pronounce the name as three syllables); in the latter case, this would help make it clear I’m referring to multiple members of the Perkins family.
Then again, my favorite tactic at times like this is to be an evader, and rewrite the sentence so I don’t have to make a tough decision. For example, “the kindness of Mr. Perkins” or “the reunion of the Perkins families”. Sometimes I like the coward’s way out!
In summary, having a couple of rules of thumb will increase your power writing skills when it comes to adding the possessive plural to proper names that end with the “s” sound. First, you can use pronunciation as a guide, adding an additional “s” after the apostrophe if that’s how you would say it. Second, you can simply “write around” the problem by rearranging the words so you don’t have to make a decision. Third, and finally, remember that the authorities disagree among themselves on this subject, so your decision is final.