A double negative construction happens when we negate a so-called affixal negation, or positive words that are negated by the affixes “un-”, “im-”/“in-”/“il-”, “dis-”, “de-”, and “-less,” as in “unavailable,” “imperfect,” “inelastic,” “illegal,” “disregard,” “decamp,” or “worthless.” If our intention is to use a statement using affixal negation, we must see to it that the words “no,” “not,” or “never” isn’t used to negate it. For instance, the sentence “It is not immoral to steal” is a grammatically incorrect double negative whose sense is exactly the opposite, “It is moral to steal.”
