This post has been inspired by my friend who questioned the apostrophe in sunglasses’ fans. And who could blame him? Britain’s schools teach their pupils that such apostrophes indicate possession, so he, not at all unreasonably, asked whether the fans actually belonged to the sunglasses, which, of course, they didn’t. This, however, does not make this apostrophe incorrect. And this is why.

English nouns have two cases: the common case (boy/boys) and the genitive case (of the boy = boy’s and of the boys = boys’). The common case is the base form – the one we see in a dictionary: apple(s), compassion, grammar, house(s), London, Manhattan, police, Tuesday(s), war(s). The genitive case is more nuanced because it conveys a range of meanings.

Admittedly, one of the functions of the genitive case is to indicate possession – but it’s far from the only one. But, because of the indoctrination – albeit unwitting – by British schools, some people use the terms genitive and possessive interchangeably; others seem unaware of the former altogether. However, equating the genitive case with possession is an oversimplification because, as I’ve mentioned, the genitive conveys also other meanings. Those meanings are listed below.

• Possessive genitive: John’s book (the book belongs to John)

• Subjective genitive: John’s application (John made an application = the application was made by John)

• Objective genitive: John’s release (John was released = they released John)

• Genitive of origin: John’s story (John told a story)

• Descriptive genitive: a boys’ school (a school for boys)

• Genitive of measure: ten days’ leave (the leave lasted ten days)

• Genitive of attribute: John’s courage (John is/was courageous)

• Partitive genitive: the house’s roof (the roof is a part of a/the house)

As for the noun classes with which the genitive frequently appears, they are as follows:

• Personal names: the Robinsons’ family house, Obama’s reforms
• Personal nouns: the twins’ older brother, my mother’s cooking
• Animal nouns: the cat’s tail, this dog’s collar
• Collective nouns: the nation’s resources, the committee’s decision

The genitive is further used with certain kinds of inanimate nouns:

• Geographical names: Africa’s future, China’s growth, California’s climate, London’s inhabitants, Harvard’s alumni

• Locative nouns (for regions, institutions, heavenly bodies, etc.; some can be similar to geographical names): the world’s population, the hotel’s entrance, the club’s pianist, the church’s mission, the school’s history

• Temporal nouns: a day’s work, yesterday’s news, this year’s sales

• Other nouns relevant to human activity: mind’s eye, my life’s goal, love’s young dream, the novel’s structure, the play’s philosophy, science’s influence, the treaty’s ratification

So that’s the genitive case in a nutshell. Needless to say, this exposition is going straight into my book on grammar, which, I hope, will dispel many myths surrounding the subject.