I am starting to come around to a slightly more complicated view than either of the obvious positions of 'there is' or 'there isn't', having by instinct started out with a view close to Nicholas' and yours, Alex. I think I would now state it like this: there has to be a 'received context' in any discourse community, meaning a general consensus on grammar and lexical meaning - and this has to always be in a state of creative tension with the forces of liberation (who, if allowed their head, could rapidly dismantle language to a state of mutual incomprehension). Students of linguistics may recognise this is getting pretty close to Bakhtin's ideas.
In day to day exchanges, this means we have (according to our dispositions) to endure or enjoy a constant battle between the social forces whose interest lies in structuring, consolidating, centralising and focusing the language in use, and those whose interest is served by a freedom of expression, a decentralised and sometimes ecletic creation of personal ideolects. And that this process of ebb and flow is actually what language is centrally about.
