[azile0]

Q. Isn't it "Alcibiades's"?

A. No, shut up. Lalala can't hear you.

Haha.. Nice. I'm looking forward to this one.

[tinfoil]

it's an inside joke.

[TopAce]

And what's the motivation behind that? Gotta ask that, because I prefer the s's way.

[tinfoil]

you sound like a snake when you say it.

[Renegade Paladin]

And what's the motivation behind that? Gotta ask that, because I prefer the s's way.

Because s's is grammatically incorrect. 

[tinfoil]

Actually, I'm not sure that it is, but it's sure annoying.

[TopAce]

And what's the motivation behind that? Gotta ask that, because I prefer the s's way.

Because s's is grammatically incorrect. 

S's is definitely correct. Check any detailed grammar book, printed or online.

[Blue Lion]

And what's the motivation behind that? Gotta ask that, because I prefer the s's way.

Because s's is grammatically incorrect. 

S's is definitely correct. Check any detailed grammar book, printed or online.

I did. Every one says it is in the writer's discretion to pick. Goober and I had the same argument.

[Goober5000]

Writer's discretion is a concession (hey, that rhymes!) because it's so common.  But yes, s's is grammatically correct.

[BS403]

That's odd, I was always told that when a word (any word) ends in s to simply add an apostrophe to make said word possessive.

[tinfoil]

It's more or less at the discretion of the author.

[Droid803]

Not really.
S's is grammatically correct, but is awkward to read (and to pronounce).
So people just drop the s at the end.
Hey, languages evolve.

[swashmebuckle]

S' is correct for non-proper nouns ending in S, but proper nouns can go with either s's or s' at the writer's discretion.  Most people do pronounce an extra "es" sound at the end of these names except in cases where the last syllable is pronounces as "eez" (common in Greek names like this case), but s's on paper looks unpleasing to a lot of people, especially when it's "ss's", so it's up to you.  There may also be AE vs BE and regional differences in general preferences, but, as usual, that stuff only really matters to linguists and people with way too much free time .  In this case, I'd say the style points definitely go to Alcibiades'  .  Anyway, way to go with the simultaneous announcement and release!

[Goober5000]

S' is correct for non-proper nouns ending in S

I think you mean plural nouns.

Anyway, I found the Strunk and White rule online.  Ironically, Alcibiades would probably count as an "ancient proper name ending in -es".

[eliex]

Most people write it as "s'" rather than "s's", although being grammatically incorrect.
Then again, I say that "s's" are getting phased out of the English language like so many other words.

[ARSPR]

HLP is great. 

Not only I enjoy a great game, but I also get free advanced English lessons. 

(Because they are advanced, not absurd, aren't they?  )

[Blue Lion]

Take notes, there will be a test later.

[swashmebuckle]

I think you mean plural nouns.

Nope nope, if I'm not mistaken (which is always a distinct possibility), the possessor's being singular or plural should not change its written treatment; the only important consideration is whether the noun ends in S or not (which most plurals happen to).

So bus' is correct, but bus's is not.  Buses' is correct, but buses's is not.  And just for the hell of it, busses' is correct, but busses's is not.  As a side note, they are all pronounced identically. 

It's only proper nouns (among nouns ending in s) that can elect to have an extra bonus S after their apostrophe, though in the "special exception" cases like Jesus', Achilles', and many other old timers there is never an extra S (this was news to me).

So Purvis' and Purvis's are both acceptable, and the one chosen might depend on either the specific author's style or the first syllable of the following word.  So Purvis' style might look better to some than Purvis's style, but Purvis' jawline is probably weaker than Purvis's jawline.  It's impossible to get it right, and you get yelled at when you're wrong.  Nuns patrol the aisles with their rulers ready to tattoo your wrists at the first sign of a slip.  Basically it's a nightmare, one you can only wake up from by realizing that no one in their right mind gives a damn about it.  Then you admit that you have a problem and the healing can begin.

In conclusion, Spanish is a beautiful language with remarkably uniform grammar, syntax, and spelling.  Sorry to crap up your nice FAQ thread.  I promise I'm done now.

[Goober5000]

Nope nope, if I'm not mistaken (which is always a distinct possibility), the possessor's being singular or plural should not change its written treatment; the only important consideration is whether the noun ends in S or not (which most plurals happen to).

You're mistaken.   Here, I'll provide examples:

The wheels on the bus -> The bus's wheels
The wheels on the buses -> The buses' wheels

That's the universal pattern, whether the noun is common or proper.

[Snail]

The wheels on the bus -> The bus's wheels
The wheels on the buses -> The buses' wheels

The emboldened s doesn't necessarily need to be there right?