Actually, double negatives are less indicative of textual meanings and more indicative of geographical and social background. They are heavily used in certain dialects of English and still persist despite the common connotation of uneducation that they carry. In recent years, however, they seem to have changed from a dialectal variance to more of a code used by even educated or affluent speakers. That's not to say it still has no dialectal usages, but it's become less of a classist differentation and more of a formality meter.
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