A grammar, he claimed, should be more than a description of old utterances. It should also take into account possiblefuture utterances. In short, the traditional viewpoint that the main task of linguists is simply to describe a corpus of actual utterances cannot account for the characteristic of productivity, or creativity, as Chomsky preferred to call it. This, as we noted in Chapter 2, is the ability of human beings to produce and comprehend an indefinite number of novel utterances