A double negative uses two negative words (in bold below) in the same clause to express a single negative idea:
We didn't see nothing. [ = We saw nothing.]
She never danced with nobody. [ = She didn't dance with anybody.]
The rules dictate that the two negative elements cancel each other out to give a positive statement instead, so that the sentence ‘I don’t know nothing’ could literally be interpreted as ‘I do know something.’
Double negatives are standard in many languages and they were once a normal part of English usage, too. But they aren’t considered acceptable in standard English today and you should avoid them in both speaking and writing. Just use a single negative instead:
We didn’t see anything.
She never danced with anyone.
There is one type of double negative that is considered grammatically correct and which people use to make a statement more subtle. Take a look at the following sentence:
I am not unconvinced by his argument.
The use of not together with unconvinced suggests that the speaker has a few mental reservations about the argument. The double negative creates a nuance of meaning that would not be present had the speaker just said:
I am convinced by his argument.
Back to Grammar tips