The double negative is a peculiarly English device very much used in what might be called ‘literary’ English. It is designed to give more emphasis to a phrase. For example, the writer of a novel could say, “She was unusually attractive.” The term is self-explanatory but not very advanced. Using the double negative, the same writer could say, “She was not unattractive to men, though not pretty.”
As far as I know, this literary device is unusable in the Romance languages. In Spanish, for instance, the double negative is used to emphasise the negative, not to negate it, ie. “Ellos no tienen nada que temer”. ‘no’ and ‘nada’ are both negatives. Sensitively translated into English, it would read, “They have nothing to fear,” with only one negative. Directly translated however, the phrase would be ungrammatical – “They don’t have nothing to fear,” which in English is unacceptable. In Spanish the phrase is perfectly acceptable.
The danger of the double negative is that use of it can make the writer verbose. Instead of simply saying, “It is natural to be afraid,” which economically speaks for itself, some writers would expound, “it is not unnatural to be afraid’. I will borrow and paraphrase some sentences from Anthony Powell and Stephen Fry:
“There is not a man of you, I can safely say, who would not be in a stronger position to face the world if he had no inexperience of employment in a big concern. However not a few of you will not be cogniscent that I am turning my attention to rather different spheres. Indeed, I have not been silent to not a small number of you, when I explain not without clarity about these changes in my life when we meet in the City . . .” Of course Powell did not compose this speech for his character Widmerpool. He is much too expert an author to get stuck in this sort of literary mire. But many modern authors are not experts like Powell.
And Stephen Fry:
“I understand the University has already sold film and television rights?”
“That is not insubstantially incorrect”
“How confident are you that this is genuine?”
“Let me turn the question round and say that I am not confident that it isn’t. I don’t think that it is insignificant. A student of mine is not unaware of its potential lack of insignificance.”
“Would he not have destroyed the manuscript if he had never wanted it read?”
“I cannot deny myself the right to believe that he left it to be found.”
“Well, that’s not an uninteresting point, certainly. I don’t know many people who couldn’t express doubt about the strategies that the authorities adopt in situations not a million miles dissimilar to this one and I don’t think that’s something we shouldn’t be unafraid to shirk addressing or confronting.”
Again, this is not genuine Stephen Fry. I have re-arranged the phrases, but Fry’s character Prof. Anderson does indeed speak like this throughout the book The Liar, and very funny it is too. Actually, many distinguished authors fall into the trap of using the double negative to gain effect, thus not avoiding the danger of becoming long-winded, if not uncomprehensible.
Beware the double negative or you may not find it unsurprising that you find yourself up to the neck in what some people, not in themselves uneducated, may describe as fecal matter.