Defining categories

There are three kinds of definition which are given for lexical categories like noun and verb (cf. Croft 1991, Payne 1999:142-3). American (and European) structuralists relied entirely on structural definitions, i.e. the definition of a category is the set of behaviors shared by the members of the category (Payne's Type 1):

32.Def. The positions in which a form occurs are its

FUNCTIONS.⁸

Thus the word John and the phrase the man have the functions of 'actor', 'goal', 'predicate noun', 'goal of preposition', and so on.

33. Def. All forms having the same functions constitute a FORM-CLASS.

...

37. Def. A form-class of words is a WORD-CLASS. (Bloomfield 1926/1957:29)

Generative theory offers another category of "explanation", the a priori explanation (Payne's Type 2):

The question of substantive representation in the case of grammatical formatives and the category symbols is, in effect, the traditional question of universal grammar. I shall assume that these elements too are selected from a fixed universal vocabulary, although this assumption will actually have no significant effect on any of the descriptive material to be presented. (Chomsky 1965:65-6, emphasis added)

That is, the categories are simply stipulated by the theory; the linguist's task includes identifying them, but there is no need to define them. In current Generative theory categories are defined in terms of syntactic "distinctive features", e.g. N,

V; while in theory these may be taken as simply stipulated by Universal Grammar, in practice they are identified by syntactic behaviors, even if these behaviors may be regarded as "tests"

for the presence of an a priori category rather than defining qualities of an inductive one.

Radically different in form and spirit are definitions in terms of the function of a category (Payne's Type 3), like the traditional "person, place or thing," or the definition of noun and verb in terms of "time stability" (Givón 1984), actual (Croft 1991) or potential referentiality (Hopper and Thompson 1984), or different types of hypothesized conceptual representations (Langacker 1987). For generations breath and ink have been expended arguing about which of these two is the

"right" kind of definition (which particular definition is the best is, of course, a separate question):

8 Bloomfield is using the word function in a different sense than ours. In the older sense used by Bloomfield, function

refers to syntactic function, e.g. as subject or object

(Bloomfield's "actor" and "goal"), etc. Thus his function is equivalent to our syntactic property (see below); I use function in a sense closer to Bloomfield's class meaning.

Some grammarians, feeling the failure of such [functional] definitions as those just given have been led to despair of solving the difficulty by the method of examining the meaning of words belonging to the various classes: and therefore maintain that the only criterion should be the form of words. (Jespersen 1924:60)

In fact, most of us regularly spend time trying to convince our beginning linguistics students of the superiority of structural definitions over the traditional functional one. But there is no logically necessary conflict between the two types of definition, which do very different kinds of work.

Structural definitions are diagnostic--they allow us to identify a noun, verb, etc., when we see one. And the most persistent and important argument raised against the legitimacy of functional definitions is that, without exception, they are spectacularly unable to do this in any non-circular way--the only evidence for a claim that 'fire' is a thing, and 'burn' an event, is that fire is a noun, and burn a verb. What functional definitions are is explanatory--once we discover, through structural analysis, that a language has--or that many or even all languages have--a particular category, a functional definition of the category is an attempt to provide an account of why languages might have it. And, just as the fatal weakness of functional definitions is that they are not operationalizable, so the traditional and inescapable criticism of purely structural definitions is precisely that they are not capable of providing such an explanation.

But surely we need to be able both to identify categories and to explain their existence. If all nouns have a certain set of behaviors in common, we can hardly claim to have an explanatory linguistic theory without an account of why those particular behaviors cluster together. Of course structural analysis must come first--there's no point in trying to explain the facts before we know what they are--but just as obviously it is only the first step in constructing an explanatory theory of lexical categories. This is not an issue for those theoreticians who explicitly eschew explanation of the sort that we are interested in.

2.1.1 Structural categories

If linguistic categories are anything, they are at least categories. That is, they are characterizable in terms of linguistic properties common to their members. Any linguistic form, from morpheme up, has an internal structure, and a set of

possible higher-order structures in which it can occur. A linguistic category is defined by those structural and combinatorial properties which its members share. Thus any morphological or syntactic construction or process constitutes a feature which is part of the definition of each of the categories to which it refers. Let us refer to shared characteristics as syntactic properties of the category which shares them. Thus grammatical number, possessive inflection, and eligibility for subject, object, or prepositional argument status are among the syntactic properties of nouns in English.

A major methodological innovation of Generative Grammar has been the development of more sophisticated methods of syntactic analysis which permit more, and more subtle, generalizations to be discovered.

If we approach the problem inductively, any generalization about a language which refers to some subset of the morphemes or words of the language thereby defines a class of morphemes or words. Just as in phonology, our expectation will be that each such class is a natural class, i.e. can be characterized by some motivated syntactic property independently of the particular generalization which defines it (cf. Jackendoff 1977:31). If in some language we can define a particular category by the fact that its members, and no other words, inflect for tense, we assume that there is something about the members of that category, which distinguishes them from all other words, which makes them an appropriate locus for tense marking. And just as in phonology, where we find rules which define to non-natural classes, it is a result of diachronic processes which have obscured the motivation for what was once a natural generalization. Just as in phonology, the most natural classes are those defined by the largest number of and/or the most basic (however that may be determined) generalizations.

But it is quickly evident that syntactic properties must be hierarchicized somehow--that some characterize more basic categories than others. So, we speak of categories and subcategories. For example, all true nouns in English share certain fundamental behaviors, in particular, the ability to head a NP. But within that category, mass and count nouns are distinguished as subcategories by the set of possible determiners occurring with the noun when not inflected for plural: the/a/some child, the/some/*a mud. Relator nouns like top, back, front, place, behalf, are similarly distinguished by lacking morphological noun properties--in particular, they do not inflect:

1) on Suzie and Fred's behalf/behalves 2) on behalf/*behalves of Suzie and Fred

But more significantly, they are distinguished by the fact that they can head only a very specific NP structure, with an obligatory modifying PP and no other dependents. Thus they do not occur with other NP components, except for their characteristic dependent PP:

3) I will be there in her rather difficult place.

4) *I will be there in rather difficult place of her.

Among the external combinatorial properties which characterize a category, we can distinguish between mention in

"basic" and derived constructions, essentially equivalent to old-fashioned kernel and transformed sentences. For example, Preposition in English has two syntactic properties common to all its members: occurrence directly before a NP, and occurrence in sentence-final position--but the latter is possible only in the derived preposition-stranding topicalization construction. English Auxiliary, on the other hand, is defined solely by the latter kind of property:

Auxiliaries are those words which participate in a specified way in negative and question constructions. Other than this they have nothing whatever in common. Have and be conjugate irregularly, the modals not at all. The modals take bare-infinitive complements, like make, let, come and go.

Progressive be, like like, etc. takes an -ing-complement, while have and passive be take a past participle.