Unfair to Greenberg

ECOLING at aol.com ECOLING at aol.com
Tue Aug 31 06:14:39 UTC 1999

Concerning the Cambridge use of unrooted trees,
as compared with Greenberg, both of them draw
conclusions about relative similarity, hence potentially
about relative closeness of genetic relationship on a
probabilitistic basis.  Since Greenberg does not reconstruct
proto-languages, the "roots" of his trees have only the
weakest of implications, if any at all beyond the usual
distinctions from a dialect chain or dialect space,
so that is not an important difference between his
expression of results and the "unrooted trees" of the
Cambridge project.

Greenberg of course is a human being making human
judgments, therefore not as explicit in what the criteria
of the judgements are as a computer would be,
and potentially not as consistent.  Just like any other human
being doing Multilateral Comparison.

The Cambridge computer algorithms are of course
applied mechanically, and are therefore completely
consistent.  In addition they are explicit about what
their criteria are for decisions.

That does not mean the Computer algorithms are better.
Computer algorithms can sometimes be better than an
individual human for very complex tasks if they can be
refined over time by many people, and when appropriate,
conflicting goals can be harmonized or balanced.
But unless done very very well they can also be inferior to
human judgements.  Computer algorithms can have biases
built into them, and more consistently applied biases
are worse than biases applied less regularly.

Trask cannot stand the idea that Multilateral Comparison
done by Greenberg and done by Cambridge has much in

Trask is making a completely unfair comparison below.


>> Trask seems to approve the Cambridge use of Algorithms,
>> and to discount Greenberg's judgements of similarities.
>> He calls the one "rigorous" and the other "highly informal".




>> I don't think either is necessarily better than the other.
>> The assumptions built into each can systematically bias the
>> results, and such bias will be an increasing problem for BOTH
>> with increasing time depth and increasing noise in the data.


>But the Cambridge work is mathematical and fully explicit; it can be
>tested.  G's work is not and cannot be.  The Cambridge group make it
>fully explicit what they are counting and how.  Greenberg does not.
>The *only* criterion involved in Greenberg's work is Greenberg's

The comparison just expressed is not fair by any stretch of the imagination.

To be fair,
Trask could have compared Greenberg with another human being
doing classification by Multilateral Comparison.
(We are after all talking about a situation of very distant relationships,
where are genetic relationships at all, so recurring sound
correspondences are not likely to be established, and THAT sense
of "explicit" cannot distinguish Greenberg from another human.)

Or Trask could have generalized and referred to ANY human
making judgments, so the burden of the difference would not
fall selectively on Greenberg.

But as stated previously, it is not even
certain that computer algorithms are in general better than
human judgments in these matters.

Lloyd Anderson
Ecological Linguistics

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