I'm afraid that your logic is off. There isn't an English speaker on the planet who would gloss "don't say nothing" as 'say something',
2006 wrote: You are taking things out of context. I was talking about the claim that substandard English is as logical as standard English is. It's not!
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We'd have to get our terms straight before we can discuss this. Not "substandard", 2006, "nonstandard".
That's the magic of language. And this illustrates the paucity of thinking that has gone into prescriptivism. Imagine, looking to Robert Lowth for advice on English. An absolutely preposterous idea!
The motive is perfectly clear, 2006. It's imperative that we describe language as it's actually used.
Of course you can do that if all you want be is a descriptivist. But you can't be sure that you are aware of all the usages in the world; so you will only be describing the uses that you know of. And if you are aware of all the uses, you will offer the student a mass of information with no guidance. After all, there is no incorrect English as far as you are concerned.
First things first. I've never said that "there is no incorrect English".
Your logic, again, is a bit off. I don't have to be aware of all the usages for all the dialects of English. I only have to give accurate information as to what is standard and nonstandard English for my dialect. I can offer advice, subject to correction, for what works for other dialects.
But for the issue at hand; telling ESLs that a double negative equals a positive is highly misleading because it doesn't, in either standard or nonstandard English in any dialect of English.
That's the only way that ESLs can ever hope to become truly fluent in language. We've seen, time and again, prescriptions put forward here at this site that can't be defended. Calling something "correct/incorrect", as I've noted many times with substantial backing from language science, is simply inaccurate.
Your ambition is winning out over reality. You're not going to make many ESLs as fluent as you are, but there is a good chance many of them will be very confused! That is strictly your own biased opinion. Again, this is only your opinion.
It's hardly only my opinion, 2006. One good example, you haven't been able to defend the prescriptive notion that a double negative equals a positive.
The better question is, why do some studiously ignore the science, favoring instead canards, old wives tales, pure fabrications.
By "language science" you mean descriptivism.
Indubitably, that's what I mean. It would be a stretch of monstrous proportions to even suggest that prescriptivism had any connections to science.
You might as well keep blue for a while longer.