Language distance
In a quest to determine and describe in a "scientific" way how difficult it is to learn a given target language for a given language speaker (and not denying the other learning drivers such as motivation, exposure etc...), I was wondering if there were elaborate studies of language distance.
What I have seen so far is incomplete : - lexical distance looks only at ... lexical distance, not language distance (which would include syntax, morphology, phonology etc...) - phylogenetical analyses do not look at similarities or differences that go "beyond the language tree", and definitely does not apply to the comparison of 2 languages that are not deemed "genetically" related at all (such as Mandarin and English, or Arabic and Persian)
Many thanks in advance