Off-Topic: The English Genitive

As my regular readers already know, I am passionate in my support of the English language. I adhere strictly to correct spelling, and by "correct" I mean British spelling. I grudgingly accept that my American cousins spell certain words differently, but I still dislike words like "color" and "traveler". They grate on me whenever I read them.

This article is about the correct spellings of genitive words in English using apostrophe-s. Fortunately this does not differ on the other side of the Atlantic, so my American readers can read on. When I went to school I learnt that genitives are formed by adding an apostrophe and the letter s, unless the word ends in an s, in which case only an apostrophe is used. For plurals no apostrophe is ever used. Those were the rules, no exceptions. Since leaving school I've read a large number of books and magazines, and I've realised that there are exceptions to these rules. I recently had a heated debate with someone just as passionate about the English language as I am, because he refused to accept any exceptions. That's why I have decided to make this off-topic post.

First, what is an apostrophe? In handwritten English it's usually identical to a comma, but raised slightly higher than lower case letters. In computer typography it's simplified to a vertical bar. In the case of serif fonts the top of the bar is often thicker, making it look like a rounded triangle, as in the image above.

Let's take an example of correctly formed genitives:

The books belonging to a school: The school's books.
The books belonging to schools: The schools' books.

Both are pronounced the same, but are spelt differently. In spoken conversation the meaning would usually be made known by the context. In written English the spelling tells the reader which is meant.

Now for an exception. What do we call the daughter of a boss? In spoken English nobody would hesitate to pronounce the word identically to the plural form "bosses", but how is that spelt? My purist friend rejects the exception and would write "the boss' daughter", even though this spelling does not reflect the pronunciation. I believe he is wrong. Correct is:

The daughter of the boss: The boss's daughter.
The daughters of the bosses: The bosses' daughters.

This is an easily definable exception. Whenever a word ends with a double s, the genitive is formed by adding apostrophe-s. So we would also write "the ass's tail" and "the Goddess's temple".

With singular words ending in a single s the case is less clear cut. It is best to follow the pronunciation. In the case of the planets we talk about "Mars' surface" and "Venus's surface". If there is any doubt it's never a mistake to omit the s after the apostrophe. Nobody would complain about "Venus' surface".

For the sake of completeness, let's consider the formation of plurals. Is it always incorrect to use an apostrophe to form plurals? Here too there are exceptions which are generally accepted.

1. An apostrophe is used to form the plural of numbers.

I rolled three 5's in a row.
He went to school in the 1920's.

2. An apostrophe is used to form the plural of single letters.

Remember your p's and q's.
This sentence contains five e's.

3. An apostrophe is used to form the plural of abbreviations.

He completed three PhD's.
I own over a thousand CD's.

There seems to be some controversy over the third exception. Many people would accept the first example but reject the second. I've heard it said that an apostrophe can only be used in the plural if the abbreviation ends with a small letter or dot. However, this doesn't seem to be backed up by common usage in books and magazines. I'm not sure about this rule myself. I haven't been consistent in my spelling, even in this blog. I used to write "DVDs" and "CDs", but now I prefer "DVD's" and "CD's".