From a Computer-Assisted Stemma to a Phylogenetic Tree: The Medieval Dutch Martijn Trilogy by Jacob van Maerlant

This paper examines how computer-assisted stemmatology can bridge the methodological divide between traditional and new philological approaches to medieval textual criticism, using Jacob van Maerlant’s Martijn Trilogy as a test case. With 18 surviving witnesses—including eight recently discovered manuscripts—this Middle Dutch text provides extensive evidence for understanding scribal variation and manuscript transmission. We reconstruct the 1918 stemma by Verdam and Leendertz and test more traditional stemmatic algorithms and Bayesian phylogenetic methods on datasets of varying inclusivity. We show that computational approaches with more traditional constraints on the classification of readings fail to reconcile conflicting genealogical developments in a single tree, while a Bayesian phylogenetic analysis that models these developments in terms of other scribal and demographic factors can overcome their conflicts and offer a result that measures the reliability of proposed relationships between witnesses. The results reveal that newly discovered single-quire manuscripts cluster with previously dismissed “worthless” fragments, such as E and Z, supporting recent evidence for rapid textual circulation during the second half of the 14th century. This clustering can explain the extensive variation in later witnesses. Ultimately, the Bayesian analysis confirms, refines, and expands on Verdam and Leendertz’s reconstruction of the transmission history using traditional methods. We show that even when such an analysis is independent of Verdam and Leendertz’s judgments about original readings, its results strongly agree with Verdam and Leendertz’s 1918 stemma, which suggests that Bayesian phylogenetics captures many of the relationships they proposed between the manuscripts of the Martijn Trilogy.