Word Categoriesnoun in front of a verb. This rule then tells us that the expressions in (15) are
grammatical and those in (16) are not:
(15) a John smiled
b cats sleep
c dogs fly
d etc.
(16) a ran Arnold
b emerged solutions
c crash dogs
d etc.
This is not meant to be a demonstration of how English grammar works, but how a
rule which makes reference to word categories can produce a whole class of
grammatical expressions.
We call the set of positions that the grammar determines to be possible for a given
category the distribution of that category. If the grammar determines the distribution
of categories, it follows that we can determine what categories the grammar works
with by observing distributional patterns: words that distribute in the same way will
belong to the same categories and words that distribute differently will belong to
different categories.
The notion of distribution, however, needs refining before it can be made use of.
To start with, as we will see, sentences are not organised as their standard written
representations might suggest: one word placed after another in a line. We can see this
by the following example:
(17) dogs chase cats
If distribution were simply a matter of linear order, we could define the first position
as a position for nouns, the second position for verbs and the third position for nouns
again based on (17). Sure enough, this would give us quite a few grammatical
sentences:
(18) a dogs chase birds
b birds hate cats
c hippopotami eat apples
d etc.
However, this would also predict the following sentences to be ungrammatical as in
these we have nouns in the second position and verbs in the third:
(19) a obviously dogs chase cats
b rarely dogs chase birds
c today birds hate cats
d daintily hippopotami eat apples
It is fairly obvious that the sentences in (19) are not only grammatical, but they are
grammatical for exactly the same reason that the sentences in (17) and (18) are: the
nouns and verbs are sitting in exactly the same positions regardless of whether the