What is the articulatory logic behind the "a/an" rule in English?

Solution 1:

"Are there many cases that can pointed to in English where we similarly avoid consecutive vowel sounds?" I'm not English, but the a/an questions reminds me of the word 'idea', that it's often pronounced as if followed by a sort of 'r' prefacing vowel sounds (i.e. 'idea of...'): [ai'di:ə]. According to the IPA, 'ə' is used as in British English 'butter'. As you say, it must due to a co-articulatory reason (vowels are open, palatal sounds, and it may be somewhat difficult, if not unpleasant, to pronounce two of them in a sequence and the speaker seems to need an 'infix' to interrupt the continuum). But then why written English follows the same rule? There it's not an articulatory problem... F. A. P.S. I am Italian, but my last name has a foreign orygin and it's often mispronounced. The interesting fact is that the first letter is 'A', followed by a 'd': well, almost every Italian inserts 'n' between the two, apparently for euphonic reasons.