The zany American film Airplane contains the following dialogue:
Stewardess: Excuse me, Sir, there’s been a little problem in the cockpit.
Passenger: The cockpit! What is it?
Stewardess: It’s a little room at the front of the plane where the pilot sits, but that’s not important right now.
Humour frequently depends on the violation of linguistic rules and expectations, and this exchange is no exception. But the relevance of the comic extract to the present chapter is that it raises the question of what the norms of usage of the impersonal pronoun it and the demonstrative pronouns this and that are, and why the stewardess’s response to the question ‘What is it?’ is absurd in this situation. If the passenger had not known what a cockpit was, he would probably have asked: ‘The cockpit? What’s that?’, rather than ‘What is it?’ or ‘What’s this?’, Clearly, it, this and that occupy separate domains in the way they attach to items in discourse which should be amenable to description.
Descriptive linguists do not offer any adequate explanations of this particular usage. It is fair to say that linguists writing within the transformational-generative paradigm consider the problem of the Airplane text to be beyond the purview of sentence grammar and to belong to ‘pragmatics’ (see Evans 1980, who rehearses arguments put forward by Chomsky and others, but who still seems unhappy with the sharp line between grammar and pragmatics). But even those overtly engaged, from a discourse or pragmatic viewpoint, in describing intersentence relations do not do sufficient justice to it, this and that in the kind of function displayed and exploited for humour in the Airplane exchange.
Some studies touch on the problem indirectly. Crymes (1968:64-70), looks at contrasts between do so, do it, do this and do that as substitutes but is only concerned with the relationship between the whole substitute clause and the clause it replaces, whereas the present chapter casts its net considerably wider. Bolinger (1972:56), although solely considering relative that, does touch upon the significance of choosing a demonstrative rather than it, when he says that ‘the demonstratives single out and set off their noun