Genealogical
Coherence
One of the problems facing
editors of the New Testament is the phenomenon of mixture (sometimes called ‘contamination’)
from multiple sources within the text of a single manuscript. This makes it
very hard, if not impossible, to construct a stemma, or family tree, of how
manuscripts relate to each other. In other textual traditions, this is often
done based on ‘shared errors’ which demonstrate the dependence of certain
witnesses on others and thereby indicate that their text is likely to be
secondary. The adoption of digital editing processes, however, has led to new
methods of examining relationships within the textual tradition. Chief among
these is the Coherence-Based Genealogical Method (CBGM), used in the production
of the ECM. A fundamental difference between this method and traditional
stemmatics is the distinction between the manuscript and the text it carries.
In the framework of the CBGM, the text is the witness, not the manuscript with
its codicological and paleographical properties. While traditional stemmatics
focuses on common errors, the CBGM addresses the issue of textual contamination
by considering different types of coherence. The first measure is the
percentage agreement of the text of any two witnesses included in the edition (their
‘pre-genealogical coherence’). By creating a ‘local stemma’ of how readings
relate to each other in each variation unit, it is then possible to compare the
relationship of witnesses wherever they differ, expressing it in terms of the proportion
of ‘prior’ (earlier) and ‘posterior’ (later) readings. Each local stemma is
constructed by the editors using traditional philological principles to
establish how the readings are related in each unit, largely based on internal
criteria. The ability of the computer to process the relationships of witnesses
based on each place of variation provides editors with an indication of the
closest potential ancestors for each witness and, beyond that, the textual
shape of the tradition as a whole. The measure of ‘genealogical coherence’ is
the extent to which each variant reading is attested in witnesses which are
related overall (‘coherent attestation’) or whether it emerged on multiple, unrelated
occasions (‘incoherent attestation’). Beyond this is the concept of ‘stemmatic
coherence,’ which expresses the extent to which the text of each witness can be
explained by the smallest possible combination of its potential ancestors in an
optimal substemma. Combining all substemmata creates a ‘global stemma.’
This genealogical approach is
used alongside the traditional criteria by the editors of the ECM when
constructing the editorial text (described as the Ausgangstext or ‘Initial
Text’). It thus constitutes a novel means of enhancing reasoned eclecticism by
adding information which can only be provided by computer processing. Like the understanding
of the textual quality of individual documents, the CBGM data is built up in an
iterative ways, beginning with straightforward variation units and then using
the genealogical relationships built up from these to consider more complex
cases, it is worth underlining that the CBGM does not itself determine the
earliest reading: rather, it provides analyses of the consistency of the textual
tradition which may assist editors in identifying the earliest reading,
especially in cases where other criteria are evenly balanced. In addition, the
CBGM sheds new light on the development of the biblical text by indicating the
extent to which particular readings are likely to be related or may have arisen
independently. (H. A. G. Houghton, A Textual Commentary on the Greek New
Testament: A Companion to the Sixth Edition of the United Bible Societies’
Greek New Testament [Stuttgart: Deutsche Bibelgesellschaft, 2025], 21*-22*)