The answer to either question is not clear, because, for one reason, the questions are not asked. What is clear is that in any case descriptive or structural linguistics is not a theory of language in the ordinary use of the word theory.
2. Behaviorism, both in its early Pavlovian and Watsonian versions, and in the later refinements of modern learning theory, does indeed offer a plenary model of language as phenomenon, which meets all the specifications of explanatory theory except one: It is wrong.
S-R theory, however modified by little s’s and r’s, by “intervening variables,” “dispositions to respond,” “habit structures,” “generalization and analogy,” “stimulus control,” “network of associative connections,” and the like, fails to address itself to, let alone explain, those very features of language behavior which set it apart from other forms of animal communication, e.g., the phenomenon of symbolization or naming, the sentence as the basic unit of language behavior, the learning performance of a child, who, upon exposure to a fragmentary input of a language, is able to utter and understand any number of new sentences in the language — this after a relatively short period and without anyone taking much trouble about it.
3. Transformational generative grammar is not an explanatory theory of language, although it has been advertised as such (Chomsky). That it fails to serve as such is not a consequence of its stated objective, which is in fact correct; namely, to specify the character of the device which mediates the processing of the input, the primary data, and the output, the grammar of the language. Nor does it fail as theory primarily because of the putative and unconfirmed status of so-called “deep structures,” from which surface structures are derived by transformations (Hockett).
Transformational grammar is not an explanatory theory of language as phenomenon but rather a formal description, an algorithm, of the competence of a person who speaks a language. There is no evidence that this algorithm bears a necessary relation to what is happening inside the head of a person who speaks or understands a sentence. There is evidence in fact that it does not.
Transformational grammar also fails as theory because it violates a cardinal rule of scientific explanation, namely, that a theory cannot use as a component of its hypothesis the very phenomenon to be explained. That is to say, if one sets out to explain the appearance of an apple on an apple tree, it will not do to suppose that apple B, which we have in hand, derives from putative apple A, which we hypothesize as its progenitor. An adequate account of the origins of either apples or sentences must contain in the one case only nonapple elements, e.g., pollen, ovary, ovule, etc., and in the other case nonsentential elements. So. it will not do for an explanatory theory of language which must presumably account for the utterance and understanding of a sentence or “surface structure” to hypothesize a “deep structure” as its source when deep structures are themselves described as “kernel sentences” (Chomsky) or “underlying propositions” (Chomsky), when in fact it is the phenomenon of sentence utterance itself in whatever form, kernel sentences or propositions, that is unique among species and therefore, one would think, the major goal of theorizing.
3.1. The main error of a generative grammar considered as a theory of language is that its main component is syntactical with semantic and phonological components considered as “interpretations” thereof (Chomsky). This awarding of the prime role to syntax rules out nonsyntactical elements, for example, semological and phonological components, as primitive generative components of deep structures and in effect posits syntax as an underivable and therefore unexplainable given.
Thus, the phrase-marker or general rule of sentence formation is given as the coupling of syntactical elements:
S → NP-VP
In point of fact, the phrase-marker does not represent the class of all classes of sentences or even the class of all declarative sentences. Consider the one-word sentence in which a child points at a round red inflated object and looks questioningly at his father, whereupon the father says Balloon. Where are the NP and VP of this sentence? What have been coupled here are not two syntactical elements but a class of sounds and a class of experienced objects. The only way this one-word naming sentence can be captured under a syntactical rubric is to consider it as an elliptical version of the NP-VP form That is a balloon, and even this strategy does not give an account of the special semiotic status of the demonstrative that. To parse the one-word naming sentence syntactically is to tailor data to fit theory. It is rather for theory to accommodate data.
It is important to notice, as we shall presently see, that while this one-word sentence does not fit the syntactical phrase-marker NP-VP, it fits very well the more informal definition of a sentence given by the ordinary-language analysts as comprising (1) what one talks about and (2) what one says about it (Strawson). What the father and child are talking about is the experienced balloon itself considered as a member of a class of such objects. What the father says about it is that it is named by a class of sounds balloon.
3.2. The phrase-marker NP-VP describes a subclass of declarative sentences. A general rule of sentence formation must accommodate nonsyntactical as well as syntactical elements such as “noun phrases” and “verb phrases.”
3.3 The central component of the LAD is not syntactical but rather semological-phonological (Chafe). The syntactical component is nothing more nor less than the formal properties which issue from the semological-phonological linkage and later from combinations of semological-phonological complexes or semantically contentive words (Brown’s usage, see Brown and Bellugi).
Thus the formal properties of syntax are already present in two-word combinations of “contentives” in children’s sentences. Later these formal properties are explicitly marked by the addition of “functors” (Brown and Bellugi).
3.4. Accordingly, a rule of sentence formation must be sufficiently general to accommodate both the purely syntactical NP-VP sentence and the naming sentence in which a class of experience (semology) is linked with a class of sounds (phonology) (Chafe).
Some such general rule may be formulated as follows:
(1) Sentence → S (is) P
The “subject” and “predicate” form seems advisable for no other reason than that these terms are sufficiently general to accommodate both naming sentences and NP-VP sentences. Thus “subject” and “predicate” are used not to revive Aristotelian categories but as a shorthand description of a sentence as comprising (1) what one talks about and (2) what one says about it. “Subject” fairly describes both the balloon in the one-word naming sentence Balloon and the NP in The boy hit the dog.