Can Parent and Daughter co-exist?

[X99Lynx at aol.com]

In a message dated 9/8/99 4:06:14 AM, kurisuto at unagi.cis.upenn.edu wrote:

<<Several on the list have brought up cases such as Latin, Sanskrit, and
Arabic as counterexamples to that last assertion.  Part of the problem is
in defining what we mean by a "living language". >>

When Larry Trask made the assertion that a parent cannot co-exist with a
daughter, I tried to avoid it by renaming the narrow PIE language/proto
languages "Celtic1....Celtic6."   To avoid the terminology issue.

Somehow this has turned into a dialogue about the eternal changeability of
language.  Which is irrelevant.  Here's why:

How long did Old Norse stay Old Norse?  How long has Modern English stayed
Modern English?  What's the longest a "language" can stay the same language?
Can it stay the same "language" for a hundred years?  Two hundred years?

Does anyone have an answer?  Can a "language" stay the same "language" for
400 years?  Let's assume that's the outside margin.

Now, how long does it take for a dialect to develop in that parent and turn
into a different language?

Anybody who has used "the perpetual changeability of language" buzz phrase
can put down their hands.  Your answer is obvious - in no time flat.
Certainly less than 400 years.

If a language can definitionally stay the same language for 400 years, and if
a daughter can develop in last than 400 years, then its obvious.  A daughter
can be in existence while the parent is alive and well.

Here's another example:
When was the last exact date Latin was a "living" language, a "natural"
language, a "first language?  Pick any date.  January 17, 601 AD.   Let's say
the last native speaker died that day.

What language was everyone else speaking in the meantime?  Or did they all
switch to Romance daughter languages the next day?

(You can't really call those daughters dialects at that point, because if a
dialect of Latin survived, then Latin survived.)

Common sense says that Latin as a native language would have had to co-exist
with vernacular languages that lived on after it died.  Or those vernacular
languages would have had to come out of nowhere the day Latin died.

Common sense says parent and daughter can co-exist.

Once again, I believe Larry Trask was referring to a methodological
assumption.  Though I don't know the basis of it.

Regards,
Steve Long