erotesis
A figure of speech whereby a question is asked in confident expectation of a negative answer.
he would ſometimes break off in a ſudden and ſpirited Epiphonema, or rather Erotesis […] and demand it categorically of his antagoniſt, Whether he would take upon him to ſay, he had ever remember'd,—whether he had ever read,–or even whether he had ever heard tell of a man, call'd Tristram, performing any thing great or worth recording?–No–, he would ſay,–Tristram!–The thing is impoſſible.
Where it comes from
From Late Latin erotesis, from Ancient Greek ἐρώτησις (erṓtēsis), from ἐρωτάω (erōtáō, “I question”).
Adapted from the Wiktionary entry erotesis (CC BY-SA 4.0).