Presupposition and Entailment in Pragmatics

The listener perceives that the information presented is necessarily true rather than just the presupposition of the person asking the question.

Non- factive presupposition: it is an assumption that something is not true. For example, verbs like "dream", "imagine" and "pretend" are used with the presupposition that what follows is not true.

I dreamed that I was rich. (>> I am not rich)

We imagined that we were in London. (>> We are not in London)

Counterfactual presupposition: it is the assumption that what is presupposed is not only untrue, but is the opposite of what is true, or contrary to facts. For instance, some conditional structures, generally called counterfactual conditionals, presuppose that the information, in the if- clauses, is not true at the time of utterance.

If you were my daughter, I would not allow you to do this. ( > you are not my daughter)