I am not a linguist, but my girlfriend is. She is working on her Masters degree in Linguistics and plans on going for her Doctorate to become a Professor. She absolutely hates grammar nazis, and if given the chance she will always explain at length why being a grammar nazi is sophomoric and indicative of insecurity and an irrational need to feel superior. I'm sure she would love to comment on this, but she is asleep right now, so I will do my best!
A lot of people seem to be under the impression that there is such a thing as "good grammar" and "bad grammar." There isn't. There is no reason why what is typically called "good grammar"--the kind you generally learn in English class--is better than other ways of putting the language together. The only reason there is "good grammar" is because the people who are currently in charge of this country like to think their dialect of English is superior to others, and discriminate against them. The grammar used by people in the inner city is just as valid a way to speak English as any other. Sorry, English majors, but there is no basis for your field other than social inequality.
Language is not something that is learned, at least not in the same way we learn other things. Language is Acquired. Our brains are specially designed to use language, and this occurs independent of intelligence. So long as you do not have brain damage, you will speak your native language with internally consistent grammar. You generally learn the languages you are exposed to as a kid, and at a certain point your brain "hardens" and becomes less able to acquire new languages, but as a kid language is one of the things that your brain is most dedicated to. It is instinctive, to the point where groups of kids will spontaneously invent their own fully developed, fully grammatical language if they are not exposed to an existing language. Non-native speakers will sometimes use flawed and inconsistent grammar, but this is because their brains have not fully acquired it. And interestingly enough, if parents speak a broken, inconsistent form of a language around their child, the child will automatically "correct" the grammar so that it is internally consistent and shows all the hallmarks of native consistency. This does not mean that they will use the same grammar or dialect as the rich, elite speakers of the language. But by all scientific standards it will be just as Right.
So all you grammar nazis out there take heed: if you disagree with someone, go ahead and disagree with them. But disagree with their ideas. So long as communication is established, language has done its job, and nitpicking the tiny details of how someone else uses the language does not show how smart you are. It shows how boring, close-minded, and arrogant you are. It's like getting a letter in the mail but throwing it out without reading it because the sender spelled your name wrong on the envelope. You know how the rest of the world gets annoyed with Americans because we don't bother to learn anyone else's language most of the time? Grammar nazis do that within their own language! Get over yourselves!
