ell.stackexchange.com:
(1) The house has a cat in it.
my variant:
(2) The house has a cat in itself.
As far as I understand, "itself" must be correct here.
But I can't understand how it is possible to use "it" instead of "itself".
Why is "it" grammatical here?
What's the difference between (1) and (2)?
For what it’s worth, in itself would be acceptable with verbs that were more active. Thus
The AI system found a bug in itself.
There, using it would change the sentence’s meaning to be that the thing in which the system found the bug was other than the system itself.
But with your sentence, there is no ambiguity about what or who is being described as containing or possessing the cat, so the simpler pronoun it is correct.
Compare it to
You know my favorite shirt, the one I wore to the party? Well, it has a hole in it,
which means exactly the same thing as “… Well, there’s a hole in it.” You could not say, *”There’s a hole in itself,” because the reflexivity would be doing something misshapen like trying to point back to the hole rather than the shirt.
The sentence (2) is incorrect. We use object pronouns (it), not reflexives (itself), after prepositions of place (in).
You may want to read this British Council article on reflexive pronouns.
We only use "itself" (or similar pronouns like "myself" and "yourself") when it's possible for the object of the verb or prepositional phrase to be something other than the subject, so "it" would be ambiguous. Using "itself" makes it clear that the object is the subject.
But there are many verbs that can only act on the subject. In that case, "it" refers to that subject, and "itself" would be redundant.
"have" is a verb that can only describe the possesions or contents of its subject, so we say "has X in it." It's not possible for the house to have a cat in something else, so we don't need "-self" in the pronoun.
But a person can hurt someone else or themselves. So we say "Joe hurt himself" because "Joe hurt him" would mean hurting some other person.
This is a good question. Unfortunately there does not appear to be a simple rule that works 100% of the time to explain whether a pronoun should be reflexive (-self) or not.
CGEL (p. 1489) gives examples where, for the pronoun to be interpreted as referring to the same thing as the subject, the reflexive form is required, optional, or impossible:
It might be easiest to think of "The house has a cat in it" (or "She has a baby inside her") as involving an idiom: "X has Y in/on/... Z", where Z is a non-reflexive pronoun whose antecedent is X.
There are other idioms with "have" where the pronoun WOULD be reflexive, e.g. "John has the house to himself." ("John has the house to him" does not make sense.)
The English reflexive isn't actually a reflexive. It's an intensive, as evidenced by the fact that it's different from the oblique in the first and second persons (me vs. myself, you vs. yourself) unlike many other languages (mich vs. mich in German, for example). It's used for the reflexive because English lost its original reflexive, and the first and second persons were dragged along by analogy.
As a result, there are many, many cases where one would expect to use a reflexive in another language, but use a simple oblique in English, even in the third person. This is one of those: since we don't particularly care about the house (it's the over-all topic, the cat, as new information, is what's really important), we use the simple oblique "it" rather than the intensive, and incidentally reflexive, "itself" to avoid bringing attention to it.
This is especially true given where the "itself" would be. There are two places an intensive pronoun can be placed - directly after it's antecedent, as in "I myself will do it", or at the end of the utterance, as in "I will do it myself". Because your proposal would put the "itself" at the end, it would be an intensive regardless, and you might as well say "the house itself has a cat in it" - note that we still don't use the reflexive in the last position!
Aside: The reflexive possessives are more transparently intensives first, as they are open compounds of the possessive pronoun and the word "own", rather than closed compounds of pronoun plus "self", and we rarely use them unless we are being intensive, rather than reflexive. I bet you didn't even know English had a reflexive possessive until now
