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What is a double negative?
A double negative is the use of two or more negatives in the same construction. Standard English, in most cases, does not permit using two negative words in one clause: "That means I didn't say nothing is unacceptable." However, standard English does permit double negatives in two circumstances: 1) when both negatives are logically required because each is negating something different as in "We can't not take this bus or we will be stuck here for the whole night," and 2) when the word not is combined with a negative prefix and it has the effect of producing a weak or polite positive as in "The hairdo is not unattractive," or "I am not inclined to disagree." Double negatives fall into two categories: 1) cases where the meaning is emphatically negative, and the phrase is common in many varieties of the language (though considered non-standard), as in "I never said nothing to nobody," and 2) the meaning is rhetorically positive and the construction is part of standard English, as "You can't not respect their decision."