Saturday, January 04, 2020

Edmondson Thesis on CBGM Now Available Free Online

A recent email from Gerd Mink reminded me that Andrew Edmondson’s Birmingham doctoral thesis is now online here. Andrew and I exchanged some emails in the first year of my own PhD and I’ve been looking forward to the completion of his work ever since. I’m especially interested because he takes a different approach to the question and a different corpus than me. So, we now have the benefit of two (my own bias admitted) thorough examinations of the CBGM. I hope to read this soon. Congrats to Andrew!

An analysis of the coherence-based genealogical method using phylogenetics

The Novum Testamentum Graecum: Editio Critica Maior is the first major critical edition of the New Testament for a century, aiming to document the New Testament’s textual history through its first millennium. To date, two of the six volumes have been published. As part of this project the Institut für neutestamentliche Textforschung in Münster has developed the Coherence-Based Genealogical Method (CBGM), a computer-aided method designed to handle complete sets of textual evidence and to identify their initial text and textual history. The CBGM is widely held to be difficult to understand and its results are treated with scepticism.

Phylogenetics is the study of relationships between groups of organisms and their evolutionary history. Phylogenetics and the CBGM (and wider textual criticism) have many commonalities. This thesis provides a thorough examination of the CBGM using phylogenetics.

Part One documents the literature surrounding the CBGM and includes a worked example of the process. Part Two explores the ECM data for John’s Gospel and identifies appropriate methods for applying phylogenetics to it. Part Three compares the results of phylogenetics and the CBGM. It concludes that the CBGM is producing valid results from the data, but could be improved in a number of ways.

1 comment

  1. Congratualations to Ed! I've been reading his dissertation, and I've especially appreciated chapter 3, where he walks the reader step-by-step through the process of the CBGM using a few verses in John 6 as an example. He even highlights the iterative nature of the process by doing a first pass through the local stemmata, checking textual flow diagrams, and then doing a second pass through the local stemmata. Since he developed his own implementation of the CBGM in Python for his work (available at, his dissertation also offers some unique insights into how he handled specific implementation details often glossed over in other literature. It's been enlightening seeing the places where his implementation and that of the CCeH for Acts ( differ.