A presupposition is background belief, relating to an utterance, that
- must be mutually known or assumed by the speaker and addressee for the utterance to be considered appropriate in context
- generally will remain a necessary assumption whether the utterance is placed in the form of an assertion, denial, or question, and
- can generally be associated with a specific lexical item or grammatical feature (presupposition trigger) in the utterance.
The utterance John regrets that he stopped doing linguistics before he left Cambridge has the following presuppositions:
- There is someone uniquely identifiable to speaker and addressee as John.
- John stopped doing linguistics before he left Cambridge.
- John was doing linguistics before he left Cambridge.
- John left Cambridge.
- John had been at Cambridge.