[rewboss]

apex, I'm not suggesting that we should tell ESLs that it's perfectly fine to use double negatives (although there are some teachers who believe quite strongly that we should). We teach ESLs standard English for very good and practical reasons, and standard English proscribes the double negative with a negative meaning. That, however, has little to do with the natural evolution of the language, and more to do with an arbitrary decision made by academics who were great logicians, but lousy linguists. You don't use double negatives because you've been told it's unacceptable: but saying something doesn't make it so.

I sometimes have to tell my students that double negatives are a feature of most non-standard dialects (they often find examples in literature and are quick to ask), but, never fear, I do tell them they shouldn't try to use it themselves: in most situations they're likely to be in, it would be frowned upon and would give a very unflattering impression of the speaker. This is a question of style and register rather than grammar.

I'm merely saying that you shouldn't put a value judgement on such things. What violates the rules of standard English may be perfectly acceptable within the Cockney grammar, or the Westcountry grammar. Standard English is the de facto standard we all agree on, but that makes it useful and desireable, not "better" or "more correct". Indeed, speaking standard English where a non-standard dialect is expected can -- and often does -- expose the speaker to ridicule, borne of a kind of inverse snobbery: it's "posh talk", and marks the speaker out as an outsider.