A Typology of Word Categories(114) friendly friendlier friendliest
lovely lovelier loveliest
manly manlier manliest
This would seem to suggest that the two morphemes have different statuses and as the
adjectival -ly is clearly a derivational morpheme, we might use this to argue that the
adverb -ly is inflectional.
A final argument for seeing adjectives and adverbs as being of the same category
has to do with the system of categorisation introduced in the preceding section. Above
we pointed out that while verbs are able to take nominal complements, nouns are not.
Adjectives are like nouns in this respect. For example, when we derive an adjective
from a transitive verb, the adjective must take a prepositional complement, not a
nominal one:
(115) a observe the results
b *observant the results observant of the results
All adjectives are like this, even those not derived from verbs:
(116) a fond his sister fond of his sister
b keen crossword puzzles keen on crossword puzzles
c *certain the answer certain of the answer
If we assume that this property is related to the [+N] feature, then we can account for
why nouns and adjectives pattern alike in this respect, as both are [+N] categories.
Note that prepositions and verbs, the [–N] categories, can have nominal complements.
Adverbs behave like nouns and adjectives in not being able to have nominal
complements:
(117) a Mary minds her manners
b *Mary carried out her duties, mindfully her manners
c Mary carried out her duties, mindfully of her manners
We shall see a little later that the question of what complements adverbs can take (and
when) is a complex issue. However, as they never take nominal complements under
any circumstances it is safe to assume that they are, like adjectives and nouns, a [+N]
category. As adverbs are thematic categories they are also [–F] and thus they have
either of the following feature specifications:
(118) a [–F, +N, –V]
b [–F, +N, +V]
The feature set in (118a) is that of nouns and we have no reason to believe that adverbs
are a type of noun. We are therefore left with the feature set (118b), which is that of
adjectives. Hence it seems we are forced to accept that adverbs and adjectives are of
the same category by the system we have devised.
The difference between adjectives and adverbs is in how they are used: a [–F, +N,
+V] category that is used to modify a noun is called an adjective and one that is used
to modify a verb or a sentence is called an adverb. That they often have different forms
is not by itself a problem, as there are certain nominal elements, for example, that have
different forms depending on how they are used: