We already saw that English, like many other languages, has ways to indicate particular
information structure within a sentence.
We use that fronting operation, particularly in order to indicate contrast with something
that's been said before, but there are other constructions that can be used to gain particular
effects, and one's that's used is the it-cleft, which is particularly used to convey focus,
that is, it’s used to convey that a particular constituent conveys new information, while
another part of the sentence is old information, information that's presupposed, which is assumed
to be agreed.
An example of an it-cleft would be something like "It was my dog that ate the homework",
where it's agreed that something ate the homework, and the new information that I've given you
is that it was my dog.
The information structure of these is a very interesting topic in itself, but for us, the
crucial point here is that that part that's in focus has to be a constituent.
So we can use this, then, as a diagnostic for constituency.
In order to do that in practice, we have to think of a kind of recipe for clefts.
So one way of thinking about the recipe is we start from a sentence.
So let's take the sentence "My sister loves ripe Italian tomatoes" and we want to know
whether "ripe Italian tomatoes" is a constituent or not.
The way we’d construct a cleft with that as the focus is first we’d move it to the
beginning of the sentence.
So if the sentence was "My sister loves ripe Italian tomatoes", we'd move "ripe Italian
tomatoes", and we'd get "Ripe Italian tomatoes, my sister loves."
Then we have to separate that part that we've moved from the remnant of the sentence, the
sentence that it's moved from.
We separate it either with ‘that’ or with a relative pronoun 'who' or 'which', depending
on what's appropriate.
So then you'll wind up with "Ripe Italian tomatoes that my sister loves".
And then the other part of the cleft is the 'it' and the form of the verb 'be', so when
you preface those to what we've just done, you'll wind up with "It is ripe Italian tomatoes
that my sister loves."
That's a perfectly grammatical sentence, so it's evidence that "ripe Italian tomatoes"
is a constituent in the original sentence, where the original sentence, you'll remember,
was "My sister loves ripe Italian tomatoes.
So it's quite a long process, but the reason it's important to think of that whole recipe
is that the same sequence of words can appear as a constituent in one context, but may not
be a constituent in another context.
So when you're testing a sequence of words in a sentence, you need to test it relative
to that sentence.
So that's why in this case we see that we start from the sentence, the question was
in the sentence "My sister loves ripe Italian tomatoes" is "Ripe Italian tomatoes" a constituent?
And so we construct the cleft on that sentence.
And that's crucial for using it as a diagnostic for constituency.
We can use clefts to diagnose constituency not only of noun phrases but also prepositional
phrases.
So, for example, if we took the sentence "My sister found some loose change behind the
sofa cushions" and I want to know is behind the sofa cushions a constituent, the way I
could test that sentence would be to construct the cleft "It was behind the sofa cushions
that my sister found some loose change."
So that's a grammatical sentence, and that tells us that in the original sentence "My
sister found some loose change behind the sofa cushions", “behind the sofa cushions"
a constituent.
In fact, it's a PP.
There are other constituents in that sentence; there are other clefts that you can make.
So you could say "It was my sister who found some loose change behind the sofa cushions"
or "It was some loose change that my sister found behind the sofa cushions."
So each of those different clefts pulls out a different constituent from the original
sentence.
So now we have quite a lot of information about the constituency of that original sentence.
However, there are some limitations to this as a diagnostic for constituency.
In particular, depending on the dialect of English that you speak, it may be limited
as to whether you can focus Adjective Phrases or Verb Phrases in this construction.
So, many dialects of English don't allow you to focus either of those types of constituent.
So, uhm, "My sister is very tall"; "It's very tall that my sister is."
For some speakers of English that's grammatical; for many it's ungrammatical.
So depending on the dialect this constituency test is not available for Adjective Phrases,
and the same applies for Verb Phrases.
That doesn't actually mean that in those dialects those sequences, so Adjective Phrases, don't
exist, that those aren’t constituents.
It's the fact that it-clefts are limited in what kind of constituents can be focused.