English grammar - Roger Berry 2012

B2.1 Definition
B2 Pronouns
Section B Development

Pronouns are a closed word class and their number is quite small. The traditional definition is that they ’take the place of nouns’, hence their name. However, there are two problems with this definition. First, many pronouns are not replacing anything, for instance:

Somebody must know the answer.

It is raining.

Here somebody and it are not replacing any noun, and it is difficult to think of nouns that could take their place.

Second, where pronouns do constitute a replacement, it is noun phrases that they are equivalent to, not nouns. In other words, all the words that go with a noun are replaced, as well as the noun.

I saw the girl with the long blonde hair.

is related to

I saw her

and not ’I saw the her with the long blonde hair’.

So for a formal definition of pronouns we can mention two characteristics:

a) structurally they are equivalent to noun phrases (see A3) and can function as subjects or objects (see A8)

b) usually they occur alone, without modification (rare exceptions would be some­thing new, or poor you); however, quantifiers such as some (see A3) are commonly followed by postmodification with an of phrase:

You can fool some of the people all of the time.