But still it’s a good principle (unless you’re a dyed-in-the-wool Derridean) that the spoken language has in many ways a primacy over writing or other derved frms of language. For me among many others that is not absolute of course, and there are many interesting things that can be said about written language that do not derive from equivalent points about speech. Yet in general most description as well as analysis begins with the spoken language and may beadapted or extended to writing, derivatively. This is a totally accepted starting point in any American school of thought in Linguistics, and even for many Continental linguists (albeit not, as acknowledged, for insane Parisians).

So consider for instance the descriptive rule for the English spoken -s inflection giving the plural for regular nouns, and the phonologically equivalent one for the 3rd person singular present of regular verbs. [And dare I say, for the simple possessive?] There are four cases, or some would merge the last two and say there are three:

1. If the stem ends in a sibilant consonant (voiced or unvoiced), append /@z/.
2. If the stem ends in any other unvoiced consonant, append /s/.
3. If the stem ends in any other voiced consonant, append /z/.
4. If the stem ends in a vowel [necessarily voiced], append /z/.

(Items 3 and 4 could be merged since they are triggered by voicing and it doesn’t matter vowel vs. consonant. But it’s clearer this way.)

Now what is the rule or principle for the written form? (Which is somewhere between fully descriptive and fully prescriptive.) It’s actually simpler, because the orthography has -s whether the sound is /s/ or /z/ … unless you’re exceedingly hip and have some “warez” to offer, or the like.

The rule for the written forms is actually much simpler because of that, and cases 2,3, and 4 merge. There is a slight complication because of silent -e and other spelling particulars of spelling that disguise the sound.

But which is the right way to put the sibilant rule?
1A. If the stem ends in a sibilant LETTER, add -es.
1B. If the stem ends in a sibilant SOUND, add the syllable /@s/, by adding the letters -es unless the written stem already ends in -e, in which case add just -s.
(And of course “2. Otherwise, add -s.”)

The 1A and 1B will disagree in just a few cases, and most style sheets will go with the form suggested by 1B. (Think of adopted French words ending in silent -s.) But even if you go for 1A, it should be clear that the phonological description is more fundamental, and the written description/prescription derives from it by collapsing cases.

When writing fiction, I make a point of avoiding names that end in “s,” as a way of sidestepping this problem.

And then, the descriptive (and maybe even explanatory) principle (not ‘rule’ in the normative sense anyway) goes into when we do or do not add that extra syllable.

The prescriptive part, according to the Chicago Manual of Style (though I’m an edition or two behind the current one I admit) accords with how Bill lays it out, for basic cases like Morris’s. But I urge you in Jesus’ name not to take it too far; and that would be Socrates’ position too, don’t you think? And for goodness sake, recall that you don’t even always use the apostrophe.

I have had grief about this before as my surname ends in an ’s’ from some of my
differently educated friends.

The also spell and pronounce words like “alumininium” use the letter “hetch”

That being said, of course, many people — and many people whose job it is to know better — write Morris’; and I’m sure many of them, when confronted with their error, will use the “language is evolving” argument. But evolution of language doesn’t not mean that if enough people do something wrong, it magically becomes right. Maybe someday, but for now this is no different from people who don’t seem to understand that there and their are different words.

As for the possessive, I was always taught that if a word or name ended in “s”, you add only the apostrophe. (Then again, I was also told to include punctuation inside the quotations, and you can see how I follow that rule.)

But in the spirit of the day, this day, July 4th - in case it does become self-aware here goes:

“We hold these truths to be self-evident; that all posts are created equal; that they are endowed by their Creator with certain inalienable Rights, and that among these are Life, Liberty, and the pursuit of Comic Understanding.”

Which means if this post gets through, it hasn’t gotten there yet.