No such thing as 'correct grammar'

[Punish_her]

There is a correct and incorrect form of grammar. While some regional differences are bound to occur, there needs to be some overlap for two forms of English to be considered the same language. For example, a good friend from the Far East who is studying English has mastered the more subtle aspects (ie who vs. whom), but when she walked in on me watching the Wire, she was completely lost, despite the official language being English. This is because it really is not English, but ebonics, and as the vernacular and proper forms grow further apart, there is eventually a schism. Dante's The Divine Comedy is proof is this, as Italian began as a vernacular branch of Latin, but eventually became a smiliar, though different language down the road.

[thir]

There is a correct and incorrect form of grammar. While some regional differences are bound to occur, there needs to be some overlap for two forms of English to be considered the same language. For example, a good friend from the Far East who is studying English has mastered the more subtle aspects (ie who vs. whom), but when she walked in on me watching the Wire, she was completely lost, despite the official language being English. This is because it really is not English, but ebonics, and as the vernacular and proper forms grow further apart, there is eventually a schism. Dante's The Divine Comedy is proof is this, as Italian began as a vernacular branch of Latin, but eventually became a smiliar, though different language down the road.

You are talking about definitions of what actually constitutes a language - how to distinguish them from dialects and off-spring languages. This is something which scholars argue about a lot.

But my original thought was on grammar in any language, and who decides what is 'correct', and if there really is such an animal, seeing how languages change all the time.

My arguments was that no one owns a language, and trying to correct other people's grammar on a website is incomprehensible to me, as some people do here. Of course a language is defined by something a group of people can understand, so if people stary too much form usual use they may not be understood.