This study explores the diachronic development of expletive negation (EN) from Old English to Early Modern English. The EN examined in this paper involves a matrix verb with the meaning `prohibit`, `deny/refuse` or `doubt/fear` governing a subordinate clause with a negative marker whose meaning is allegedly empty. It is argued that EN is not a case of long-distance negative concord, but it is a genuine negative clause, as evidenced by the existence of emphatic negative markers. The use of EN is explained from a cognitive perspective as a speaker`s frequent (mis-)interpretation of counterfactual contexts, which is compatible with the use of the subjunctive mood.