Oddly, they aren’t just for possession.
Lately, some readers and listeners have had questions about the possessive form in English. Sometimes it comes up as a question about where (or whether) to use an apostrophe. For example, I did a blog post about the apostrophe in expressions like “two weeks’ notice,” and one commenter wrote, “There is no possessive in ‘two weeks notice.’ The notice doesn't belong to the two weeks. It should actually be ‘two weeks of notice’....”
Well, there IS a possessive in expressions like “two weeks’ notice” or “a year’s pay.” The idea that there isn’t has to do with a renaming that happened in the 1700s. That’s when the grammarian Robert Lowth decided to rename the grammatical cases in English, but before I can talk about that, I should explain what grammatical cases are in the first place.
What Is Grammatical Case?
They’re not leather-bound containers for your grammar books and dictionaries. Grammatical case is a feature of a noun that shows the noun’s function in a phrase.
For the most part, present-day English doesn’t mark grammatical cases. However, it does mark case on pronouns. When we say that the pronouns “I” and “we” are used for subjects, while “me” and “us” are used for objects, we’re talking about case. “I” and “we” are in the subjective case, and “me” and “us” are in the objective case.
English also has one more case: the possessive. “My” and “our” are in the possessive case. And unlike the other cases, the possessive case still exists not only for pronouns, but for almost every noun, including proper nouns and common nouns. Here’s an example of each, all in one phrase: “Aardvark’s mother’s birthday.” “Aardvark’s” and “mother’s” are both in the possessive case.
Renaming the Genitive Case to Possessive
So as for the renaming business, a few hundred years ago, instead of subjective and objective, English grammarians used the terms nominative and accusative, because that was what the nearest equivalents in Latin were called.
The nearest Latin case to what we call the possessive was called the genitive. But in 1763, in his Introduction to English Grammar, Robert Lowth introduced the term “objective” for use instead of “accusative,” and explicitly endorsed the word “possessive” instead of “genitive.”
According to the Merriam-Webster Dictionary of English Usage, other 18th-century grammarians followed his lead. On the one hand, this was a good change, since it’s easy to remember that objects go in the objective case. Calling the genitive case the possessive showed the connection between case forms such as “my” and “our” and the idea that they could show possession.
Possessives Do More Than Just Show Possession
Unfortunately, this last name change had a side effect. The genitive case in Latin had several functions, only one of which was to show possession. Similarly, the genitive or possessive case in English has several functions, only one of which is to show possession. But the clear relationship between the adjective “possessive” and the verb “possess” led various grammarians over the years to believe that any noun in the possessive case must refer to something capable of possessing. As the Merriam-Webster Dictionary of English Usage puts it:
The argument is a case of fooling oneself with one’s own terminology. After the 18th-century grammarians began to refer to the genitive case as the possessive case, grammarians and other commentators got it into their heads that the only use of the case was to show possession. ...
Simply changing the name of the genitive does not change or eliminate any of its multiple functions.
They also cite a study done in 1940, in which only 40% of the possessive forms were used to indicate actual possession.