In recent years the interests of linguists have turned more and more to the problems of generative grammars. A number of models have been proposed, and in debate sharply opposed to one another, but they all share a number of fundamental assumptions. I will frequently use transformationalists as examples of linguists, and transformational treatments as examples of generative grammar, and I will start from a definition worded in a characteristically transformational-generative way. I do this because they are the most generally familiar instances. But what I have to say will apply with only small adjustments to, say, stratificational generative linguists and linguistics as well.