gregod said:
I am not a linguist, but i speak both mandarin and japanese, so perhaps I am misunderstanding your statement that they are unrelated. As I understand it, while japanese developed in relative isolation from chinese, a significant part of chinese language was retained. but of course to speak one does not confer the ability to understand the other; any more than ability to speak mandarin gives one the ability to understand cantonese.
Ability to speak Mandarin and Cantonese would at least be transferable skills as they are related, just as it's easier for an English-speaker to learn, say, French, than it is for them to learn Swahili. Japanese developed in complete isolation from Chinese, so no part of Chinese language was "retained" - however a large element of Chinese has entered the language at a later stage of development as a result of contact - the same way as a large element of French has emerged in English due to contact, while the original word stock is Germanic. Or, better example, how there is a large element of English and Italian in Maltese, but Maltese is not related to those languages at all - it is a close relative of Arabic. Japanese is not related to Chinese at all, but they have interference - the writing system being the most obvious example.
Think of languages as being like a community - families and neighbours. If you are "English", then German and Dutch are your siblings, French, Italian and Spanish are your cousins, Russian, Polish, Farsi, Hindi etc are your distant cousins who you don't see very often and have grown up entirely separate from you, and Hungarian is a neighbour you don't see much of but isn't part of the family. If you are "Japanese" then you are an only child. You have some close friends such as Chinese and Korean, but they aren't relatives. You don't know any relatives your age, though you may possibly have some second cousins once removed, a long way away. As a result, you feel closer to your neighbours than you do to any potential family.
Just to elaborate on the point i made in my previous post; one can look at a word in chinese and be able to guess a reasonably close approximation of the pronunciation based upon japanese alternative "on-yomi" (chinese reading).
But this is the writing system - not the parts of speech. If you know German, you would have to struggle with the Hebrew alphabet to read Yiddish. But despite very different writing systems the languages are very closely related. Same goes for Maltese (Latin letters) and Arabic (Arabic script), or Hebrew and Arabic. We got our writing system from the Romans, who developed theirs from the Greeks, who developed theirs from Semitic scripts. But Greek as a language had nothing to do with the Semitic languages. All they gave them was a method by which to transcribe their sounds.
What is the difference between sociolinguistics and historical linguistics? How could one develop independently of the other?
Historical linguistics is, for example, concerned with the development of language, how languages developed and came to be what they are today; it's about the building of the family trees of languages, dealing with how the languages became solidified, how the rules were set for how to write it, how to speak it etc. and how this is ongoing for developing languages like Tok Pisin, Luxembourgish etc.
Sociolinguistics is, for example, concerned with the people that speak the language, how they affect it (for example phenomenon like language mixing eg Spanglish, the creation of pidgins and creoles, how language affects social position or perception of the speaker (prestige varieties, eg RP as opposed to local dialects in English), and social phenomenon like the developing German of immigrant communities. Sapir-Whorf, for example, is a purely sociolinguistic theory.