What's the Deal with Double Negatives in English?

The trouble started in the 18th century when some overly eager grammarians decided to force a couple of rules onto English (Robert Lowth and Lindley Murray, if you want to name names). Much like the rule of not ending a sentence with a preposition, they sought to make English more like Latin, what they considered the ideal language. The trouble is that English is not Latin, and so this rule is a prime example of a top-down grammar rule, which is not often followed in real life.