Relative chronology

[Sean Crist]

In an earlier post, I discussed a hypothetical case where a prehistoric
language had the series *ki *ke *ka *ko *ku.  Then a palatalization rule
k > c / _i applied; and then a merger e > i applied, giving attested /ci
ki ka ko ku/.  Let's call this attested language Language A.

Steven Long amplified this hypothetical situation by adding a related,
attested language which I'll call Language B.  Language B has /ka ke ki ko
ku/; i.e. it preserves the state of affairs which I stipulated for
Proto-AB.  Steven Long correctly pointed out that if all we have are these
two languages, there is actually a possible alternative analysis: it could
be that Proto-AB looked like Language A, with Language B undergoing the
rules *ki > ke and *ci > ki.

Both analyses work, in the sense that both analyses correctly predict the
attested forms.  Given that we can't decide between the two analyses
within the Comparative Method, this is one of those cases where it's OK to
fall back on your notions about what's phonetically plausible.  We note
that palatalization rules like ki > ci are widely attested in the
languages of the world, but un-palatalization rules like ci > ki are much
rarer.  If we accept this reasoning, then Proto-AB must have had *ka *ke
*ki *ko *ku, and more importantly here, the palatalization and vowel
merger must have applied in the order I gave them here, and cannot have
applied in the other order.

There might be other reason to believe that this is so.  For example, the
palatalization and merger might have produced alternations within
paradigms:

	Proto-AB	Language A	Language B
	*tak-utu	takutu		takut		'I run'
	*tak-id		tacid		takit		'you run'
	*tak-el		takil		takel		'they run'

(Let's say -u > 0 in Language B, and that final consonants devoice, just
to show that Language B differs from Proto-AB in other respects.)

At this point, no phonologist or historical linguist would take seriously
the idea that Language A represents the original situation.  Note that
even if we didn't have any evidence for Language B, we could still
correctly and unambiguously reconstruct Proto-AB purely by performing
Internal Reconstruction on Language A, thanks to the morphologically
conditioned alternations.  We can definitively work out the relative
chronology of the sound changes purely by looking at Language A.

But if this still isn't enough for you, suppose that Proto-AB contrasted
*/k/ and */c/; thus, Proto-AB contrasted the series *ki *ke *ka *ko *ku
against *ci *ce *ca *co *cu.  Suppose again that Language B happens to
preserve this situation (while innovating in other respects).  At this
point, Steven Long's alternative analysis becomes altogether impossible,
because the palatalization rule in Language A involves a merger.  In the
case of monomorphemic words, for example, there'd be no way to undo the
merger (and note also that at this point, Internal Reconstruction of
Language A alone can't give us the whole picture, since we can't tell
whether /ci/ represents original *ci or original *ki; but the evidence of
Language B does allow us to tell). As I discussed in detail in my last
post on phonemic split, we never posit a sporadic phonemic split if there
is an alternative account available strictly in terms of regular sound
change.

So given what we know at this point, the data of Languages A and B force
us to reconstruct Proto-AB in one way and not another; and they force us
to order the palatalization and vowel merger rules in Language A in one
order and not the other.  It makes no difference whether Proto-AB is
attested or not.  Unless I've made some egregious oversight in the way
I've set up the hypothetical situation, this particular set of facts
admits only one analysis.

Now, it true that there are many cases where the data we have aren't
adequate to distinguish the ordering of two particular rules. It's also
true that there are cases where we can't tell exactly how the rules should
be formulated, and where the ordering of the rules depends on which of the
possible formulations we pick.  But it is quite often possible to go into
considerable detail about the orderings of rules; we can often tell quite
a lot.

  \/ __ __    _\_     --Sean Crist  (kurisuto at unagi.cis.upenn.edu)
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