Complementizers and subordinating conjunctions

One important point remains to be made about subordinate clauses (in English). Most of the subordinate clauses you will come across in written texts are introduced by a special word. In (3), the complement clauses are introduced by that, in (7) the relative clauses are introduced by which, who and that, and in (8) each type of adverbial clause has its particular initial word, although, because, as, when and if. In grammars from before, say, 1965, the words introducing complement clauses and adverbial clauses were generally known as subordinating conjunctions, and words such as and or but were known as coordinating conjunctions. Conjunctions are words that (con)join clauses. Coordinating conjunctions join clauses that have the same status. In (2a), for example, the clause Captain Benwick married Louisa Hayter is of the same status as Captain Wentworth married Anne Elliott. If (2a) were split into its component clauses, each clause on its own would immediately be able to constitute a sentence and to occur in a text. The clauses are of the same order or rank, hence co-ordinating conjunction and co-ordinate clauses.

In contrast, if (8e), say, were split into its component clauses, only one of them would be able to constitute a sentence, namely the main clause Mr Woodhouse would have been unhappy. The adverbial clause of condition, if Emma had left Hartfield, cannot function as a sentence until the subordinating conjunction if is removed. Subordinating conjunctions introduce subordinate clauses. Since 1965 or so, the term ‘complementiser’ has been used in one of the major theories of syntax not just for subordinating conjunctions introducing complement clauses but for all subordinating conjunctions. This usage has spread to other theories of syntax and to grammars of English and other languages, and we too adopt it.

A problem is posed by the words that introduce relative clauses. Who, whom and which are pronouns that also function as subordinating conjunctions. That they are pronouns is indicated by the who/whom distinction parallel to he/him and so on and the contrast between who and which, parallel to the contrast between he/she and it. (The contrast between who and whom is disappearing from English. It is only used regularly in the most formal and carefully edited texts.) The WH words can be preceded by prepositions, as in the fire at which Mr Woodhouse sat. The WH words will sometimes be referred to as relative pronouns and sometimes as complementisers. Relative clauses are also introduced by that. This word does not change (in technical terms, is invariable) and cannot be preceded by a preposition – *the fire at that Mr Woodhouse sat. It is not a pronoun but merely a subordinating conjunction or complementiser.

All the subordinate clauses in (8) are optional and can occur no matter what verb is in the main clause. For this reason, they are treated as adjuncts. The above list of adverbial clauses is not exhaustive but merely illustrative. Detailed accounts of subordinate clauses in English and other languages can be found in the references at the end of the book.

To close this section, we return to conjoined clauses. Examples of conjoined main clauses were given in (2), but subordinate clauses can also be conjoined, as shown by the examples in (9). Example (9a) contains two conditional clauses conjoined by and; (9b) contains two relative clauses conjoined by but.