The composite sentence, as different from the simple sentence, is formed by 2 or more predicative lines. Being a polypredicative construction, it expresses a complicated act of thought, i.e. an act of mental activity which falls into two or more intellectual efforts closely combined with one another. It terms of situations and events this means that the composite sentence reflects two or more elementary situational events viewed as making up a unity. The logical sequence of simple sentences is not evident, so if we transform a composite sentence into a chain of simple sentence: When I sat down to dinner I looked for an opportunity to slip in casually the information that I had by accident run across the Driffields; but news travelled fast in Blackstable. If we place the sentences in their temporal succession, it will destroy the original purpose of communication.
The use of composite sentences is characteristic of literary written speech rather than colloquial oral speech. The three reasons for this relate to the actual needs of expression, the possibilities of production and the conditions of perception. This type of speech deals with lengthy reasoning, descriptions, narrations, details. Situational foreground and background, sequence of events is interrupted by cross-references and comments. Form the point of view of the possibilities of production the written speech is edited, prepared, and form the point of view of the possibilities of perception, the written speech can neglect the limits of the recipient’s immediate memory.
The true limiters of the written sentence volume are logic and style, which are in contradiction with each other. From the point of view of logic, the situation can be described in one composite sentence, however long and structurally complicated it might be. For the reasons of style the unity of events and circumstances should be presented as a chain of simple sentences, the whole complex of reflections forming a multisentenial paragraph. Which of the approaches to choose, has to be decided out of considerations of form and meaning, the purpose of the text and so on.
The first principle of classification of composite sentences is the way in which the parts of a composite sentence (its clauses) are joined together. This may be achieved either by means of special words designed for this function, or without the help of such words. In the first case, the method of joining the clauses is syndetic, and the composite sentence itself may be called syndetic. In the second case the method of joining the clauses is asyndetic, and so is the composite sentence itself.
SYNDETIC COMPOSITE SENTENCES
We should distinguish between two variants of syndetic joining of sentences, the difference depending on the character and syntactic function of the word used to join them.
This joining word may either be a conjunction, a pronoun or an adverb. If it is a conjunction, it has no other function in the sentence but that of joining the clauses together.
If it is a pronoun or an adverb (i. e. a relative pronoun or a relative adverb), its function in the sentence is twofold: on the one hand, it is a part of one of the two clauses which are joined (a subject, object, adverbial modifier, etc.), and on the other hand, it serves to join the two sentences together, that is, it has a connecting function as well.
It is to syndetic composite sentences that the usual classification into compound and complex sentences should be applied in the first place.
We start, then, from a distinction of compound sentences and complex sentences. The basic difference between the two types would appear to be clear enough: in compound sentences, the clauses of which they consist are arranged equipotently, that is, none of them is below the other in rank, they are co-ordinated.
In complex sentences, on the other hand, the clauses are arranged on the relation of domination. In the simplest case, that of a complex sentence consisting of two clauses only, one of these is the main clause, and the other a subordinate clause, that is, it stands beneath the main clause in rank. Of course, there may be more than one main clause and more than one subordinate clause in a complex sentence.
So far the classification of syndetic composite sentences looks simple enough. But as we come to the problem of the external signs showing whether a clause is co-ordinated with another or subordinated to it, we often run into difficulties. As often as not a clear and unmistakable sign pointing this way or that is wanting. In such cases we have to choose between two possible ways of dealing with the problem. Either we shall have to answer the question in an arbitrary way, relying, that is, on signs that are not binding and may be denied; or else we shall have to establish a third, or inter-mediate, group, which cannot be termed either clear co-ordination or clear subordination, but is something between the two, or something indefinite from this point of view. It is also evident that the problem is connected with that of co-ordinating and subordinating conjunctions.
Compound sentences consist of clauses joined together by coordinating conjunctions. These are very few: and, but, or, for, yet, so. Concerning some of them there may be doubts whether they are conjunctions (thus, yet may also be supposed to be an adverb), and concerning the word for it may be doubtful whether it is co-ordinating or subordinating. The meanings of the conjunctions themselves are of course a question of lexicology. What concerns us here is the type of connection between the clauses in a compound sentence.
In terms of positional structure of the sentence the subordinate clause is placed in a notional position of the other (principal). This latter characteristic has an essential semantic implication clarifying the difference between the two types of polipredication. A subordinate clause, however important the information rendered by it might be for the whole communication, presents it as naturally supplementing the information of the principal clause. For some of the clauses their position in the sentence is fixed: I fancy that life is more amusing now than it was forty years ago. The position of some of the clauses can be changed: The board accepted the decision, though it didn’t quite meet their plans. It depends on the type of the clause. In a complex sentence the subordinate clause refers to one notional constituent (expressed by a word or phrase) in a principal clause. In a compound sentence the sequential clause refers to the whole of the leading clause. So, the position of the coordinate clause is fixed.
The semantic relations between the clauses making up the compound sentence depend partly on the lexical meaning of the conjunction uniting them, and partly on the meanings of the words making up the clauses themselves. It should be noted that the co-ordinating conjunctions differ from each other in definiteness of meaning: the conjunction but has an adversative meaning which is so clear and definite that there can hardly be anything in the sentence to materially alter the meaning conveyed by this conjunction. The meaning of the conjunction and, on the other hand, which is one of "addition", is wide enough to admit of shades being added to it by the meanings of other words in the sentence. This will be quite clear if we compare the following two compound sentences with clauses joined by this conjunction: The old lady had recognised Ellen's handwriting and her fat little mouth was pursed in a frightened way, like a baby who fears a scolding and hopes to ward it off by tears. The bazaar had taken place Monday night and today was only Thursday. The first sentence has a shade of meaning of cause — result, and this is obviously due to the meanings of the words recognised and frightened. In the second sentence there is something like an adversative (ïðîòèâèòåëüíîå) shade of meaning, and this is due to the relation in meaning between the word Monday in the first clause and that of the words only Thursday in the second. In a similar way other shades of meaning may arise from other semantic relations between words in two co-ordinate clauses.
Compound sentences with clauses joined by the conjunction or (or by the double conjunction either — or) seem to be very rare. I think I see them now with sparkling looks; or have they vanished while I have been writing this description of them? Are you afraid of their biting, or is it a metaphysical antipathy?
A typical example of a compound sentence with the conjunction so is the following: The band has struck, so we did our best without it.
Besides the conjunctions so far considered, there are a few more, which are generally classed as subordinating, but which in certain conditions tend to become co-ordinating, so that the sentences in which they occur may be considered to be compound rather than complex, or perhaps we might put it differently: the distinction between co-ordination and subordination, and consequently that between compound and complex sentences, is in such cases neutralised. This concerns mainly the conjunction while and the adverbial clauses of time introduced by it, and the conjunction though and the adverbial clauses of concession introduced by it.
COMPLEX SENTENCES
There is much more to be said about the complex sentence than about the compound. This is due to several causes, which are, however, connected with one another.
For one thing, the semantic relations which can be expressed by subordination are much more numerous and more varied than with co-ordination: all such relations as time, place, concession, purpose, etc. are expressly stated in complex sentences only.
Then again, the means of expressing subordination are much more numerous. There is here a great variety of conjunctions: when, after, before, while, till, until, though, although, albeit, that, as, because, since; a number of phrases performing the same function: as soon as, as long as, so long as, notwithstanding that, in order that, according as, etc. Besides, a certain number of conjunctive words are used: the relative pronouns who, which, that, whoever, whatever, whichever, and the relative adverbs where, how, whenever, wherever, however, why, etc.
We may note that the boundary line between conjunctions and relative adverbs is not quite clearly drawn. We shall also see this when we come to the adverbial clauses introduced by the word when and those introduced by the word where. Historically speaking, conjunctions develop from adverbs, and one word or another may prove to be in an intermediate stage, when there are no sufficient objective criteria to define its status.