In John saw/didn't see the man with two heads, the definite description the man with two heads triggers the presupposition "There exists a man with two heads." (The unbelievability of the presupposition is what makes the positive utterance unbelievable and the negative one odd.)
In John realized/didn't realize that he was in debt, both realize and didn't realize that trigger the presupposition "John was in debt."
Other factives are
- (it) be odd that
- be sorry/proud/indifferent/glad/sad that
- know that, and
- regret that.
In John managed/didn't manage to open the door, both managed/didn't manage to trigger the presupposition "tried to," as in "John tried to open the door."
Other implicative verbs are
- avoided (X-ing), which presupposes "was expected to"
- forgot to, which presupposes "ought to have"
- happened to, which presupposes "didn’t plan/intend to," and
- intended to.
Change of state verbs
In Kissinger continued/didn’t continue to rule the world, both continued/didn’t continue to trigger the presupposition "had been," as in "Kissinger had been ruling the world."
Other change of state verbs are
- stop, and
- take (X from Y), which presupposes "X was at/in/with Y."
Expressions of repetition
In Carter returned/didn’t return to power, both returned/didn’t return trigger the presupposition "Carter held power before."
Other such expressions are
- another time
- come back
- repeat, and
Expressions of temporal relations
In while Chomsky was revolutionizing linguistics, the rest of social science was/wasn’t asleep, the clause introduced by while triggers the presupposition "Chomsky was revolutionizing linguistics."
Other such conjunctions triggering presuppositions are
- since, and
- In it was/wasn’t Henry that kissed Rosie, the cleft structure triggers the presupposition "someone kissed Rosie."
- The pseudocleft structure in what John lost was his wallet triggers the presupposition "John lost something."
In John did/didn’t compete in the OLYMPICS, the stressed constituent triggers the presupposition "John did compete somewhere."
In Adolph called Marianne a Valkyrie, and she complimented him back/in return, too, both back/in return, too trigger the presupposition "to call Marianne a Valkyrie is to compliment her."
In Carol is/isn’t a better linguist than Barbara, the comparison triggers the presupposition "Barbara is a linguist."
In if the notice had only said ‘mine-field’ in English as well as Welsh, we would/would never have lost poor Llewellyn, the form of the condition triggers the presupposition "The notice didn’t say mine-field in English."
- Questions presenting alternatives tend to trigger a presupposition of the truth of one of the alternatives. The utterance is Newcastle in England or in Australia? triggers the presupposition "Newcastle is either in England or in Australia."
- Questions containing interrogative pro-forms tend to trigger a corresponding presupposition containing an indefinite pro-form. The utterance who is the professor of linguistics at MIT? triggers the presupposition "someone is the professor of linguistics at MIT."