Learn English – Why ‘a friend of mine’ is not ‘the friend’s friend’

double-possessiveidiomspersonal-pronounspronouns

I have some questions about the expression "a friend of mine" and I'm quite confused with it. Actually I have found some threads about this topic but they don't hit my point. I'm not a native English speaker.

General people may interpret that "a friend of mine" is "one of my friends" but it sounds to me like "a friend of my friend" or "my friend's friend" who I may or may not know him/her. I was taught that "mine" is a possessive pronoun and it's used to replace the noun mentioned earlier; for example, This is Adèle's book so the book is hers.

  1. Why "a friend of mine" is not "a friend of my friend"? And why "a daughter of mine" is not "my daughter's daughter" or "my grand daughter"?

  2. Why we use "a friend of mine" instead of "a friend of me" to mean "my friend" but we use "a part of it" to mean "its part"? "Mine" is a possessive pronoun but "it" is an object pronoun.

I probably have read all things people trying to answer the questions but I still haven't found the comprehensive rules yet. Can anyone give the comprehensive rules for using the double-possessive form?

I myself may conclude that:
1. The double-possessive form is used when the personal subject pronoun is used.
2. If the noun indicating that the owner is a person or people, either the double-possessive form or the noun itself is used but slightly different in interpretation.
3. If the possesser is an animal, robot, or any inanimated objects; the objective pronoun or the noun itself should be used.

Anyway, is there any mistakes or leakages in those rules?

so I can say that:

a friend of mine = my friend
a computer of yours = your computer
a house if his = his house
a book of hers = her book
a school of ours = our school
a car of theirs = their car
a part of it (not a part of its) = its part
a shirt of Mary's = Mary's shirt (Mary has many shirts)
a shirt of Mary = Mary's shirt (Mary can either has only one shirt or many shirts)
a wing of a bird = a bird's wing
a leg of a robot = a robot's leg (one of the robot's leg)
an office of an engineer = an engineer's office (one of the or only office(s) of a certain engineer)
an enemy of France = France's enemy (one of France's enemies)

Is that correct?

Thank you for all of your answers. They are very helpful.

Best Answer

This is perhaps best explained by providing the relevant extract from the ‘Longman Student Grammar of Spoken and Written English’:

The double genitive is a special construction in which either the independent genitive or a possessive pronoun occurs in an of-phrase:

This was a good idea of Johnny’s.

There’s a talk by this lady from Boulder who’s a student of Sandy’s.

The woman who owns Harte’s is a friend of ours.

As these examples show, the main noun phrase typically begins with the indefinite article. In fact, the definite article does not normally combine with the double genitive: *the good idea of Johnny’s is unlikely to occur.

The meaning of the double genitive can sometimes be alternatively expressed by other constructions. Thus, a friend of ours could alternatively be expressed as one of our friends.

Here is a further explanation from ‘The Cambridge Guide to English Usage’:

The double genitive seems to serve two purposes:

emphasis. This is the effect of paraphrasing “not Jo’s fault" as no fault of Jo’s, or turning “our friend” into a friend of ours. The double genitive unpacks the phrase and foregrounds the noun rather than the person. In conversational examples such as That book of Bill Bryson’s is his best yet, the construction helps to adjust the topical focus.

clarification. Clearly a painting of Lady Rich’s and a painting of Lady Rich mean different things. The first (a possessive) makes the painting part of Lady Rich’s collection, while the second (technically an objective genitive) says that it is a portrait of the Lady herself. The duplication of the genitive is thus not redundant but clarifies the fact that the first construction is a possessive genitive.

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