We might conveniently start with two cases involving English-speakers and with which even my sternest critic (Doug) would agree:
1. The English invasion of North America
2. The English invasion of the Indian sub-continent
The first led to a language change and the second did not.
Now we’ll enter all the caveats that waste so much time:
Yes, it’s true that there are still pockets of Native American language-speaking in North America
Yes, it’s true that plenty of people in the Indian sub-continent can speak English, some even as a first language
Yes, it’s true that English has picked up various Hindi, Urdhu etc loan-words
Yes, it’s true that all the languages of the Indian sub-continent have picked up various English loan-words
Yes, it’s true that there are slight variations in North American English, English English and English as she is spoke in India
NEVERTHELESS it is an observable fact that the language got changed in North America and it remained static (to use Ishmael’s term) in India.
OK, are we all together so far? Excellent.
My book says that Model 2 (languages remaining unchanged when a country is occupied by invaders speaking a different language) is the norm.
Orthodoxy also says that Model 2 is the norm.
Where we take issue is that when Orthodoxy requires a Creation Myth i.e. when it requires an explanation for the origin of a language spoken by a particular people, it sometimes unwarrantably slips in a Model 1 (language changed by invaders).
I point out that this has happened in the case of Britain (re the Anglo-Saxons) and the French, Italians, Spanish and Portuguese (re the Romans).
[Doug: the only reason that the Romans are left off the list is that it appears in the first chapter of my book, dealing with Anglo-Saxon anomalies in the ORTHODOX account of history. Although the Romans fit in to the table just as well as do all the other invaders, I do not deal with their case until Chapter 3, and therefore could not include them.]
You are all free now to consider dispassionately the evidence for my thesis as against the orthodox thesis. However, I am obliged to point out that in matters of creation myths (especially where your own is concerned) it is sometimes difficult to be dispassionate. Where the creation myth is also an academic paradigm taught to you at a tender age by authority figures, it is doubly difficult.
But do try.