Feigned ignorance (tajahul) presents a fact as though its status were not yet decided. When the purpose is to expose an addressee’s inconsistency, it becomes a vehicle for reproach (tawbikh).
What the speaker knows and how the speaker outwardly frames the proposition are distinct. In may convert an accepted fact into a condition in order to highlight the practical or moral consequence of acknowledging it.
The hypothetical form can also remove an excuse: if the addressee accepts the premise, conduct contradicting it becomes indefensible.