The dictionary is a neutral arbitrator. It is necessary exactly because the nature of language is fluid. Using it is not an appeal to authority. It is an appeal to objectivity.
If words mean what any writer/speaker wishes them to mean, language will become useless. There has to be some governing authority or communication becomes impossible with each wrtiter/speaker using their own langauge.
Dictionaries aren't objective because they aren't handed down from the sky. From the very beginning they were filled with politics. Check out Samuel Johnson's definition of
oats. Noah Webster coming out with a dictionary at all was a political act. Issues of slang and usage are political to today.
That doesn't mean they can't be useful, but they certainly aren't objective, and they
most definitely aren't comprehensive.
There doesn't need to be any "governing authority" at all. For centuries upon centuries there were not and people understood each other just fine. I never said they can mean "what any writer/speaker wishes them to mean," I said that—contra some "governing authority" language speakers have a general understanding of what a word means.
No definition of a word is really fully accurate—think of a word in this sense as an electron. The observation pins it down with some other words, but it's sphere of meaning is beyond that.
