A double negative occurs when two or more ways to express negation are used in the same sentence. In some languages a double negative resolves to a negative, while in others it resolves to a positive. These are strictly grammatical rules and have nothing to do with mathematics. In particular, double negatives do not "cancel each other out". They are used in some languages and considered erroneous in others.

A famous linguist once made the further observation that it was unknown for a double positive ever to resolve to a negative. A skeptical voice came from the back of the lecture hall: "Yeah, right". This joke is due to Prof. Sidney Morgenbesser of Columbia University.

English

In today's standard English, double negatives are not used; for example the standard English equivalent of "I don't want nothing!" is "I don't want anything". It should, however, be noted that in standard English one cannot say "I don't want nothing!" to express the meaning "I want something!" unless there is very heavy stress on the "don't".

Although they are not used in standard English, double negatives are used in African American Vernacular English, and the London Cockney and East Anglian dialects and less frequently, but still commonly, in colloquial English. In the film Mary Poppins, Dick Van Dyke uses a double negative when he says

If you don't want to go nowhere.

Other examples of double negatives include:

Don't nobody go to the store.

or

I can't hardly wait.

Double negative also refers to even more than two negatives, like:

And don't nobody buy nothing.

Today, the double negative is often considered the mark of an uneducated speaker, but it used to be quite common in English, even in literature. Chaucer made extensive use of double negatives in his poetry, sometimes even using triple negatives. For example, he described the Friar in the Canterbury Tales: Ther nas no man no wher so vertuous (i.e. "there wasn't no man nowhere so virtuous"), and he even used a fourfold negative when describing the Knight: He nevere yet no vileynye ne sayde / In all his lyf unto no maner wight. Chaucer used these multiple negatives for emphasis and for metrical purposes.

Double negative form of the Golden Rule

The standard form Do unto others as you would have them do unto you has a corresponding double negative form: Do not do unto others as you would not have them do unto you which has a different psychological connotation; where the standard form is positive, implying a commandment which must or ought to be done, the double negative form is more neutral, merely suggesting a positive action, and commanding only that one refrain from other actions whose results one would not prefer oneself.

Double negative form of agreement

The standard form I agree has a corresponding double negative form: I don't disagree, which entails a similar psychological connotation as that for the double negative Golden Rule; where the standard form implies I will, the double negative form does not imply I will, but rather that you can, and I will not interfere.

Triple and quadruple negatives

Eggbert Williams ' song Nobody, popularised by Johnny Cash, contains the notable chorus:

Well, I ain't never done nothing to nobody.
I ain't never got nothing from nobody, no time.
And, until I get something from somebody sometime,
I don't intend to do nothing for nobody, no time.

This is an example of triple and quadruple negatives, used for emphasis.

Romance

Romance languages generally express negation by adding a word (ne in French, no in Spanish, non in Italian, não in Portuguese) to the verb and zero or more words elsewhere to indicate what part of the sentence is negated. In French, unlike the others, simple negation usually requires the word pas:

No como.

Je ne mange pas.

Non mangio.

This was originally the same as the word for "step" (Je ne marche pas originally meant I don't go a step) and later extended, to the point that ne is now often left out in colloquial speaking and pas serves as the only negating element.

The correlative negative words in Spanish and Italian are used only in negative sentences (e.g. ningún - a positive sentence uses algún) whereas some French negative words are the same as positive words. This sometimes leads to confusion for non-native speakers if the verb, and therefore the word ne, is omitted. For example "personne" can mean both "person" and "nobody", "plus" can mean both "more" and "no more".

Slavic

In many Slavic languages, double negation is the norm.

In Russian and Serbian, a double negative is correct, while a single negative is an error in grammar. The following are literal translations of grammatically correct Serbian sentences: "No one's negligence didn't nowhere brought nothing but unhappiness." (= No one's negligence did anywhere brought anything but unhappiness), "This is uncaused by nothing" (= not caused by anything).

In Slovene, much like in many other Slavic languages, double negation is a correct form, though sometimes causing confusion as to whether the positive or the negative is meant by a given (ambiguous) sentence. For example, the English sentence 'I don't know anyone' would be translated to Ne poznam nikogar (I don't know nobody); a literal translation, Ne poznam kogarkoli, is a somewhat strange construction, but means 'I don't know just anyone' (= I know someone important or special). Peculiarly, 'Nobody knows one another' becomes 'Nihče ne pozna nikogar' (No one doesn't know no one).

However, the Church Slavonic language allows only single negation (still, many norms of Church Slavonic are artificial, as it is not a spoken language).

Example of commonly used triple negative in Czech language: Nikdo nic nevyhrál meaning Nobody won anything, translated literally as Nobody didn't won nothing.

See also

• Double negative elimination