Though we can just about get our heads around commas, full stops and hyphens, it’s the apostrophe that trips us up more than any other element of punctuation.
As Lynn Truss pointed out in her book Eats, Shoots & Leaves: The Zero Tolerance Approach to Punctuation, there are lots of apostrophes around – it’s just that most of them happen to be in the wrong place.
The humble apostrophe caused nationwide embarrassment for a major toothpaste brand in the UK in early 2005.
Can you spot the mistake? If you can’t, read on. And if you can, read on anyway.
One of the commonest mistakes is to use an apostrophe to indicate plurals. It’s called the greengrocer’s apostrophe, because it’s at the greengrocer’s that you’ll see them: apple’s, orange’s, pear’s, banana’s.
The Daily Telegraph, a UK newspaper, ran a story on this phenomenon a few years back, and managed to confuse even itself, referring to the greengrocer’s apostrophe and the greengrocers’ apostrophe in the same article.
The rule for plurals is straightforward: no apostrophe. Even plurals of initials (MP, PA, ID) generally don’t take apostrophes nowadays.
So when should you use apostrophes? Here’s a quick, no-nonsense guide:
Possessives
In the singular, an apostrophe is always placed before the s to indicate possession:
the girl’s computer
that man’s shirt
Jane’s bicycle
In the plural, the apostrophe generally comes after the s:
the boys’ CDs
the members’ ID badges
the performers’ instruments
The exception to this rule is irregular plurals (where s is not added to form the plural). In that case, the apostrophe once again comes before the s:
the women’s applications
the men’s rejections
the children’s video games
the oxen’s hooves
Singular words that end in an s have caused endless debate, but the generally accepted principle is that an apostrophe and another s are added:
Jesus’s disciples
Sibelius’s music
But the debate continues, and you’ll still see Jesus’ disciples and Sibelius’ music. As with MP’s and PA’s, it’s a grey area (or, if you’re in the US, a gray area).
Pay special attention to the possessive of the word it. Logically, it should be it’s, but English isn’t all that logical, so you use its:
the council sacked its suppliers
the choir took a bow, led by its director
Missing letter
Apostrophes are used to indicate a missing letter in a contraction (when words are joined together). So it is becomes it’s, they are becomes they’re, and I am becomes I’m.
Pretty simple, isn’t it? Yes and no. From those examples, you might think the apostrophe comes between the words. It doesn’t. Remember, it replaces the missing letter, so is not becomes isn’t (not is’nt) and does not becomes doesn’t (not does’nt).
And finally…
So where did Colgate go wrong? Whoever wrote the copy put an unnecessary apostrophe after theirs. Possessive pronouns (mine, yours, his, hers, ours, yours theirs) never take an apostrophe.
The writer was probably thinking about dentists’ teeth, and thought an apostrophe was needed somewhere.
As Lynn Truss says, there are lots of them around.