(Email Removed) schrieb:
"Hello, This my first post to this group. I was asked a question by a friend of mine: Why is ... use one over the other. I don't personally think such a rule exists, but does anyone know the answer definitively?"
As you say, the pronunciation is based to a large extent on the etymology - there is no rule for the pronunciation of letter combinations in English. The "-ey" in "key" has another pronunciation and when you include names like "Feynman" you have yet another pronunciation of that combination.
Sometimes the pronunciation of a word may change over time under the influence of other words with the same letter combination or of the proniunciation in other dialects, varieties or (non-standard) accents. an example of this is the pronunciation of the word "schedule" - when I was young the usual pronunciation in Ireland and Britain of the "sch-" combintion was the same as "sh-" - now this pronunciation seems to be being replaced by the pronunciation "sk-", probably under the influence of the American pronunciation.
Regards, Einde O'Callaghan