The Oxford Dictionary of English says a double negative “is a negative statement containing two negative elements (for example he didn’t say nothing)” and “a positive statement in which two negative elements are used to produce the positive force, usually for some rhetorical effect, for example there is not nothing to worry about!” It is rather like in mathematics where multiplying two negative values together make a positive one. Two negative elements can be used to produce a positive one.
To sum up, the above-said dictionary states “According to standard English grammar a double negative used to express a single negative such as I don’t know nothing rather than I don’t know anything is incorrect. The rules dictate that the two negative elements cancel each other out to give an affirmative statement, so that I don’t know nothing would be interpreted as I know something.”
Double negatives have often been frowned upon by serious linguists, but should they be? Are there any circumstances where they are acceptable? Well, yes there are.
- It can be used for a rhetorical effect. For instance, in a rhetorical statement as in “there is not nothing to be concerned about”.
- Double negatives are standard in certain other languages, e.g. Spanish.
- The double negative was normal in Old English and Middle English, only becoming frowned upon after the 16th century. Historical fiction could therefore be expected to use double negatives to be authentic, especially in formal speech.
- In modern usage a double negative can give added subtlety to statements, such as “I am not unconvinced by such an argument”, suggesting reservations by the speaker.
- To express a weak positive, such as in “I suppose that it is not impossible”, something that is not likely but is not beyond the realm of possibility.
So, carry on with those double negatives if they seem to serve a purpose, or if they do not serve no purpose! It is quite easy to tie oneself in knots with these. As Bart Simpson once wrote on a blackboard in The Simpsons “I won’t not use no double negatives”.