My internal dictionary contains alternative spellings for some words. Sometimes I'll write 'fulfilment', other times, 'fulfillment'; 'defence' or 'defense'; 'realize' or 'realise', etc. I guess there are two ways to interpret this: (1) I oscillate between two dialects of English, each of which has a single correct spelling for each word; or (2) I consistently write in a single dialect in which either spelling is acceptable. Either way, there's some sort of linguistic indeterminacy going on. The only question is where to locate it: at the level of languages, or of spellings within a language.
Is there any substantive difference between these two possibilities? Which is the more appropriate description, and why? If we go with #2, does that mean I can escape charges of inconsistent spelling? After all, I'm consistently following the (perhaps disjunctive) requirements of my language: I always spell the word as either 'realize' or 'realise', and not any other way. So at least I'm not changing linguistic rules mid-sentence. Does that count for much?