Looking at the Private language argument it occurs to me that Wittgenstein does not really account for the developmental nature of language:
Temporal and spacial separation of Speakers will invariably introduce changes to meaning of words, changes in pronunciation and eventually completely different languages. Which means that within a splinter group an individual need to introduce a subtle change to initiate the deviation process. This means that the individual conception of the semantics and pronunciation of an word is a (main) agency of change for the common language.
Through the process of maturation an individual will frequently need to change their understanding of common language words. Not only the semantic content, but also emotional connotation and personal preferences are attached to concepts within a person's mind. When a concept is invoked by common language interaction the entire individual history of contact with that concept is invoked. These histories are, per concept, unique to individuals.
The implication is that common language is the consensual 'overlap' of individual private languages. This would seem to fall prey to Wittgenstein's stipulation that a private language should in principal not be translatable. However, while we may use wildly different mental faculties to 'process' a certain concept, when we even as much as think about communicating it we immediately invoke translation to common language. Therefore access to a private language is in principal impossible.
Is there any philosophers that have argued against the impossibility of a private language and what is their arguments?