Learn English – His vs His (possessive adjective vs possessive pronoun)

The basic "rule" is that formal written English prefers the possessive in all circumstances, while informal, conversational speech prefers the objective. Generally, the more formal the register, the more likely it is that the possessive will be used. However

• Formal English is becoming less rigid. It now tolerates the objective in many circumstances—for instance, a transitive gerund clause which acts as the complement of a matrix verb, as in snailplane's example:

  Do you mind me asking a question?

• Likewise, the possessive is hardly rare in informal English; it is particularly frequent when the gerund clause is the first constituent in a matrix clause:

  My kids KNEW their dad as they had lived with him and me until the separation... but, his leaving like that was tough on them. —from CafeMom, a meeting place for moms.

  What seems to govern colloquial use is the syntax; a gerund which plays a particularly ‘un-verbish’ and ‘noun-y’ role is more likely to take the possessive.

  So although some dogmatic ‘descriptivists’ claim that the possessive sounds ‘stilted’, in my experience this isn’t true; colloquial English tolerates a wide variety of usages.

Under the circumstances, I would advise you to stick to the possessive, particularly if you are in school or are in a field which demands a lot of formal writing. It’s easier to make a habit of using just one form instead of trying to juggle two; and the possessive will never get you into trouble.

Possessive-adjectives are not adjectives. Possessive pronouns are certainly not adjectives

Possessive-adjectives can function in some ways like adjectives (my book, red book). But they are can't form comparatives or superlatives (*a more my book, *the myest book). And they can't form a predicate (*this book is my.)

The possessive pronouns act like nouns. In modern English, they seem usually to appear in the predicate "It's mine!". In older forms of English they were seen in the subject (consider the Lord's Prayer: "For thine is the kingdom" thine is the old singular form of yours). Modern English seems to prefer "my one" in this position: "My one is better than yours."

Nouns and pronouns can appear as predicates. "It's a cat." "I want him." and so on. In the sentence "It's mine" the word mine is acting as a pronoun, not as an adjective. The word "mine" can't function as an adjective *"mine book" is incorrect.

It is best not to think of words like "my" as replacing adjectives. But instead, think of them as forming their own special class of words, which go before nouns to indicate possession.