there are many other important aspects of meaning that we convey at the same time as the factual information. If there is anything illogical about double negatives, then, it is people’s reactions to them: some hate them, some love them.
The more negatives there are in a sentences, the more emphatic the denial or rejection. Different types of double negatives have come to be used by varying groups of people.
The double negatives represent the survival of a long-established pattern of negation in English and a natural pattern of negation in language generally.