> derived from the languages of these Celtic populations who,
> at best, borrowed extensively from their Germanic rulers?
No. Harper is saying that the english language WAS the the language of the "Celtic" populations. :-)
> I suppose it's possible. Has anyone done the necessary
> linguistic research to refute the claim that the substrate of
> English is Germanic?
Harper does not question that the languages are related. He merely suggests that it more logical to conclude that, rather than English being Germanic, German is "Anglic."
> If the norm is model 2, but model 1 has clearly occured
> before (North America being the most recent example) then
> isn't it possible too that Model 1 occurred in Britain during
> the first millennium AD
Sure it's possible. But what Orthodoxy is arguing for is a low-probability event. This makes it a proverbial "extraordinary claim" for which "extraordinary evidence" in required.
Unfortunately, there's actually no evidence for the orthodox position.
> The fact that such atrocities actually occurred in relatively
> modern times and the vast majority of English speakers less
> than 100 years later are completely oblivious to it leaves
> plenty of room for similar incidents occurring in the more
> distant path between Germanic invaders and Celtic natives and
> the subsequent amnesia and creation of a myth to explain how
> the language of the Anglo-Saxons came to be dominant in
Fne. But all you have here is a case that language replacement is plausable. It will always remain improbable due to its demonstrably exceptional nature.
As we are obliged to accept the simplest (most probable) explanation that fits the facts, until convincing evidence of the sort associated with the "ethnic cleansing" scenario you describe is presented, it is more rational to assume that there was nothing exceptional about the Anglo-Saxon experience in England -- and that the English language on the Island predates the Anglo-Saxon invasion.