and all other preconditions are in effect, then A is heard as making a valid request of B for the action X.

(a) Existential Status

Have you dusted yet?

You don't seem to have dusted this room yet.

(b) Time Reference

When do you plan to dust?

I imagine you will be dusting this evening.

(c) Preconditions

1a Need for action:

    Don't you think the dust is pretty thick?

    This place is really dusty.

1b Need for the request:

    Are you planning to dust this room?

    I don't have to remind you to dust this room.

2 Ability:

   Can you grab a dust rag and just dust around?

   You have time enough to dust before you go.

3a Willingness:

     Would you mind dusting around?

     I'm sure you wouldn't mind picking up a dust rag and just dusting around.

3b Obligation:

     Isn't it your turn to dust?

     You ought to do your part in keeping this place clean.

4 Rights:

   Didn't you ask me to remind you to dust this place?

   I'm supposed to look after this place, but not do all the work.

Naturally, it is possible to challenge any of the speaker's assumptions, e.g. I could deny the existential status of X; 'I have dusted' or the time reference. 'I'll do it tomorrow' or any of the preconditions, 'It doesn't look bad to me', 'You don't need to remind me I'll do it later' etc. But the key point is that we tend to accept the conventions, even if we challenge their applicability at a particular time. Communication depends on cooperation and the withdrawal of cooperation leads rapidly to breakdown. This is certainly the case whether we limit our search for 'rules' to those which apply to individual speech acts (direct or indirect), as we have been doing here, or widen our focus to incorporate sequences of communicative acts.

Indeed, our initial attempts, when faced by something incoherent, is to try to make sense of it by using one or other of the strategies just suggested; i.e. rather than accept that the speaker/writer is being intentionally perverse, we assume that (s)he is (in spite of appearances to the contrary) trying to cooperate and to adhere to some kind of cooperative principle which regulates communication.

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