Conjunctions are words that join clauses together and thus have the capacity to create complex sentences.
There are two types of conjunction. A coordinator joins clauses in a way that gives them equal grammatical status. The main coordinators are and, but and or, and they allow us to turn a simple sentence like William likes pears into a complex sentence such as William likes pears, but he doesn’t like apples. The two clauses have equal grammatical status, because William likes pears and he doesn’t like apples can stand on their own, and still make sense. Or can be used with either to create alternatives, and neither . . . nor can be used to create negative alternatives. Coordinators can also join words together to make phrases: bacon and eggs, naughty but nice, trick or treat.
A subordinator introduces a dependent clause, that is, one that can’t stand on its own and make sense. We might, for example, say William likes pears when they are ripe and juicy, where when introduces a dependent clause. The first part, William likes pears, as we have seen, can stand on its own, but when they are ripe and juicy doesn’t make much sense without the first part of the sentence.
Coordinators and subordinators are unassuming words, but we couldn’t manage without them. They derive from words that once had lexical meaning. But, for example, is from Old English be-utan, which meant ‘on the outside’. As such, they support the argument that all language is metaphor, in that all words once related to tangible things in the world and temporal and spatial relations between them.