Seeking Grammar Police Ruling - Typo's / that possessive 's

[Carol]

Mike:
> This makes me wonder about the increasing use of 's as the
possessive with names or words ending in s already; as in James's. <snip>
> 
> I'm of two minds here; I know what the rules is and naturally desire
to follow it. But the 's is such a good written description of the 
pronunciation that I have been oft tempted to and actually have used  it. 
> 
> And I always wondered what one does with a surname that ends in s. 
That is, if there is a James Dents and all the little Dents. How 
would one distinguish between one of the Dents owning something as 
opposed to the entire family owning it? If I were to say "Dents' 
automobile" am I referring to it as James' car or the Dents' family  car? 
> 
> I supposed I could just call it the "Dense car", though James may
not appreciate that. ;D

Carol responds:

I don't know whether Dents is a real last name or not, so let's try a
real name, James Jones.

"James" and "Jones" both form their singular possessives in the same
way as any other singular noun in English (with the exception of Jesus
and a few Greek names ending in -es, such as Xerxes or Hippocrates,
which merely add an apostrophe), bu adding apostrophe s. 

So you have "James's car" or "James Jones's car."

The plural for both names is formed using -es: "The class has two
Jameses and two Roberts"; "The Joneses are flying to Scotland for
Christmas this year."

The plural possessive is formed by adding an apostrophe to the already
plural noun, "Jameses" or "Joneses":

"The two Jameses' doctrine of the Divine Right of Kings" (I'd find
another way to word the idea); "the Joneses' house."

To sum up:
Singular possessive: 's
Plural: -es
Plural possessive: -es'

Compare any other singular noun that ends in "s" or "ss," for example,
"hostess."

Singular possessive "hostess's"; plural "hostesses"; plural possessive
"hostesses'." (I can't think of a singular noun other than a name that
ends in a single "s"' "Politics" doesn't count because it's plural but
construed as singular.)

Oh. If you really want to know, James Dents's family would be the
Dentses and their house would be "the Dentses'."

Carol, who hasn't read any of the responses in this thread and hopes
she's not repeating what's already been said