Closely related to the framework of theme-and-variations in syntactic description is the distinction between deep and surface syntactic structure.36
In simple, 'theme' (main, declarative, affirmative, active) clauses, the deep
structure and a surface structure roughly coincide, they are to all intent and
purpose one and the same.37 A clause's deep structure corresponds most
closely to its semantic structure, that is to its propositional meaning. The surface structure of a simple clause, being roughly the same as its deep structure, is thus semantically transparent. It reveals the underlying mean ing relations with minimal distortion.
In most complex ('variant') clauses, on the other hand, the surface structure is somewhat at odds with the deep structure, so much so that the two must be described independently. Given the considerable difference between the two, the surface structure of complex clauses does not reveal their underlying propositional meaning, and may thus be considered
semantically opaque.
The syntactic complexity of non-theme clauses is thus the source of the semantic opacity of their surface structure. That is, in producing a syntacti cally-complex clause, one endows it with a surface structure that is not semantically transparent, a surface structure that does not correspond to its deep structure.
The distortion in form-meaning relation introduced by syntactic com plexity is not done for the heck of it. Rather, it is the consequence of the fact that the syntactic structure of complex clauses is tipped heavily toward coding their discourse-pragmatic function. But discourse-pragmatics and propositional semantics are here in direct competition for coding resources. In the process of tilting grammatical coding machinery more heavily toward
discourse pragmatics, some of the semantic transparency that is so charac teristic of simple clauses is sacrificed.
The structure of complex clauses is thus a communicative compromise between two partially-conflicting goals. Each one is served, but not fully, since the other must also be accommodated. This imperfect state of affairs is due to the fact that syntax (or grammar) is used to code two distinct func tional realms.
The best illustration of the difference between deep and surface syntac tic structure involves clauses that are syntactically — and thus semantically — ambiguous. Consider first (40) below, where the seemingly-identical sur face clause has two distinct interpretations, (40a) and (40b):38
(40) Flying planes can be dangerous.
a. Planes that fly can be dangerous (to people). b. For one to fly planes can be dangerous (to one).
The surface structure of (40) may be given by two near-identical tree dia grams, (41a,b) below. These structures are substantially the same, except for some details of their category labels. Diagrams (41a) and (41b) thus corre spond to the two interpretations of (40), (40a) and (40b) respectively.
In spite of their slight difference, neither of the surface structure dia grams (41a,b) tells us much about the meaning difference between the two interpretations (40a) and (40b). In order to accomplish that, we must now describe separately the deep structure corresponding to each interpreta tion. The one corresponding to (40a)/(41a) is:
(42) S
(42)
(43)
The meaning difference between (40a) and (40b) is now revealed to be the function of the deep structure 'source' of the surface noun phrase 'flying planes'. In the case of (40a), we are dealing with the intransitive (objectless) verb 'fly' whose subject is 'planes'. In the case of (40b), we are dealing with the transitive verb 'fly' whose object is 'planes'.
Consider next the case of the two clauses (44a) and (44b) below, whose meaning difference is clearly coded by the use of two different adjectives, 'easy' and 'eager':39
(44) a. Sally is easy to please. b. Sally is eager to please.
However, some rather trivial paraphrase manipulations of the two struc tures in (44) reveal that their 'deeper' structures must be radically different. Compare, for example, the paired paraphrases in (46) below, where the symbol [*] marks an ill-formed ('ungrammatical') expression:
(46) a. (For one) to please Sally is easy. b. *(For one) to please Sally is eager. c. found it easy to please Sally. d. *He found it eager to please Sally. e. Sally is eager to please everybody. f. *Sally is easy to please everybody. g. Sally is easily pleased (by anybody). h. *Sally is eagerly pleased (by anybody).
In the syntactic analysis of two clauses with a similar surface structure, dis covering grammatical contexts where one fits and the other does not is taken to be strong evidence that under their deceptively similar surface structures lurk two different deep structures. The two deep structures cor responding to (44a) and (44b) are, respectively, (47) and (48) below:
The deep structure descriptions (47) and (48) reveal that the adjective 'easy' in the surface structure (44a)/(45) is derived from the adverb 'easily' in the deep-structure (47). One sees now that in (44a) 'Sally' is the object of the verb 'please'. In contrast, the adjective 'eager' in the surface structure (44b)/(45) remains an adjective in the deep-structure (48). One also sees now that 'Sally' in (44b), in addition to being the subject of 'eager', is also the subject of the verb 'please'.
A similar case of syntactic-semantic ambiguity involves the complex clause:
(49) I am looking for someone to teach. Its ambiguity may be pointed out by the expansions:
(50) a. I am looking for someone to teach French.
( > ...someone so that they teach (someone) French.) b. I am looking for someone to teach French to.
(> ...someone so that I teach them French.)
The deep-structure description of the two potential senses of (49) — (50a,b) — must reveal the crucial difference concerning whether the subject of 'look-for' is either the subject or the object of 'teach'. The more expanded (50a,b), while still considerably mutilated as compared to their full-fledged deep structure, are already revealing enough to differentiate between the two interpretations of (49).
Many types of complex clauses in English are sufficiently mutilated, truncated or chopped-up so as to obscure, at least in some contexts, their deep structures — thus also their propositional meanings. However, the seeming semantic opacity and potential ambiguity of such surface structures is not necessarily a major block to communication. This is so because the dis
course context within which such complex clauses are embedded often
allows the listener to resolve their potential ambiguity one way or another. For example, if (49) above were uttered by a short-staffed highschool prin cipal at the beginning of the school year, interpretation (50a) would have been more likely. On the other hand, if (49) were uttered by an unemployed French teacher, interpretation (50b) would have been more likely.
The toleration of potential ambiguity in using complex syntax often involves subtle judgement calls. Speakers and writers make successful com municative choices by being well tuned to the discourse context of indi vidual clauses. Good communicators are particularly successful at guessing what the hearer or reader is likely to know or believe, what is easy for them to infer, what they are likely to figure out from context. In striving to be a successful user of grammar, one must remember that grammar is not about grammar, nor is it about following rules. Rather, grammar is about success
ful communication. In other words, grammar is about producing coherent discourse.
NOTES
1) Proponents of the arbitrariness of grammar are fond of asserting that if not 100% of the rules of grammar are functionally transparent, or if a single rule is not 100% transparent, a functionalist approach is untenable. This all-or-nothing approach is again consonant with the logic-machine view of grammar, rather than with a more realistic biologically-based approach.