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Subject: [APG] Re: Genealogical Theory
Date: Tue, 2 Dec 2003 22:58:29 EST


Jerry noted the lack of quantitative underpinnings to genealogical theory.

Here's my overly simplistic take:

Family history shares the theoretical basis of history generally. Genealogy
deals specifically with family relationships--biological, legal and
social--and provides the family structure on which its history must be built. Whether a
particular relationship exists at any particular point in time is an either-or
proposition. It either exists or it does not, and the only quantitative
values applicable would be binary, like 0 and 1.

The assertion of a relationship, however, is like every other scientific
"fact." It is a "best guess" based on a thorough analysis of all available
evidence--and is subject to change when new evidence becomes available.

It is theoretically possible to quantify the probability that a particular
either-or conclusion or assertion is in accord with reality, based on the
reliability and relevance of the evidence on which it is based. That would require
rating or at least rank-ordering all data items of the same type, doing the
same for each of the different types being considered, and then developing an
algorithm relating those values to an overall probability.

Should such a methodology be developed and validated, however, it would
provide much more than the sought-after theoretical underpinning for genealogy. It
would be the basis for a general model of human decision-making, applicable
to every intellectual discipline from aeronautics to zymurgy.

It would certainly represent a breakthrough in modeling cognition, and would
be a real feather in the cap of genealogy as a scholarly endeavor if a
genealogist were to develop and publish it, rather than a psychologist, systems
analyst, communications engineer or diplomatist.

As for its application to genealogy, the objective numbers would still be
subject to individual subjective interpretation of their significance. Some of us
might be quite comfortable accepting a 90 percent probability as a "yes,"
while others would insist on a 95 percent, 99 percent, or 99.7 percent
probability to put our doubts to rest. Most of us would probably be satisfied with
different levels of probabilities for specific relationships within particular
time spans or for varying purposes. Would the elegant quantification of
probability really matter, given these differences among or within the individuals who
might apply it?

How much usefulness would it add to the traditional qualitative descriptions
of confidence in our genealogical findings if we could state, for example,
that there is a 96.2 percent probability that there was a marital relationship
between a man and woman from 15 Jan 1933 to 26 April 1952, but only a 71.4
percent probability that it existed from 24 Nov 1932 to 14 Jan 1933, and a 12.8
percent probability subsequent to 26 April 1952?

As critical as evidence analysis is to the study of genealogy, the systematic
search for evidence is equally important, as can be the occasional
serendipitous breakthrough unrelated to the planned search.

Donn Devine, CG, CGI
Wilmington DE

CG, Certified Genealogist, CGI, and Certified Genealogical Instructor are
service marks of the Board for Certification of Genealogists, used under license
by board certificants after periodic evaluation, and the board name is
registered in the US Patent & Trademark Office.

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