The Thought and Ministry of a "Unionist Priest" (ἑνωτικὸς ἱερεύς): John Plousiadenos (†1500), the Council of Florence, and the Tradition of Byzantine Unionism

Doctoral Dissertation


This dissertation examines the phenomenon of the “unionists”: medieval Greek Christians who were united to the Roman Church and urged their countrymen to do likewise through the lens provided by the life and writings of the still poorly-known Cretan polymath and priest John Plousiadenos (c. 1426-1500), a theologian, pastor, and defender of the union between the Greek and Latin Churches proclaimed at the Council of Florence (1439).

Because of his unionist convictions, John was reviled by his own countrymen as a Λατινόφρων (“Latin-minded”). A slur generally deployed against the unionists in Byzantine polemical literature and implying that the unfortunate whom it labels is a crypto-Westerner and does not, therefore, belong to the “authentic” Byzantine Christian tradition. It is with this medieval slur—or equivalent formulae—that unionists have been labeled in conventional scholarly narratives on Byzantine history and theology.

This dissertation strives to understand the unionist perspective on its own terms—rather than those of its contemporary or modern critics—through the investigation of the pastoral and polemical theology of John Plousiadenos: one of the final, and most outstanding, representatives of the Byzantine tradition of unionism. After an overview of Plousiadenos’ life and works, this dissertation investigates unionism in its concrete temporal and geographical contexts and in its practical aspects: what did united Greek Christianity look like “on the ground” in the late medieval Venetian transmarine empire, specifically Crete, according to the ideals of Plousiadenos as unionist pastor? Here we find evidence of Greek unionism as an eclectic introduction of Latin theology, spirituality, and pious practice into a recognizably Greek milieu. At the same time, this dissertation considers Plousiadenos’ polemical theology and self-understanding as unionist. Placed within the context of the greater unionist tradition, this study finds that Plousiadenos strove to formulate a concept of Christian identity transcending the logic of ethno-religious schism between Latins and Greeks, a concept of Christian tradition that was truly universal, or “catholic.”

Based on the evidence provided by Plousiadenos’ writings, this dissertation rejects the assessment that John Plousiadenos (and by extension other unionists) was a “Latinophrone,” without denying the reality of Latin influence on his thought or praxis. With some qualification, it suggests positioning John Plousiadenos and the tradition he represents as forerunners to the later phenomenon of “Eastern Catholicism.”


Attribute NameValues
Author Charles C. Yost
Contributor Alexis Torrance, Committee Member
Contributor Alex Beihammer, Committee Member
Contributor John Monfasani, Committee Member
Contributor Yury Avvakumov, Research Director
Degree Level Doctoral Dissertation
Degree Discipline Medieval Studies
Degree Name Doctor of Philosophy
Banner Code
  • PHD-MI

Defense Date
  • 2019-03-29

Submission Date 2019-04-07
Record Visibility Public
Content License
  • All rights reserved

Departments and Units
Catalog Record


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