The Catholic doctrine of the Filioque—that the Holy Spirit eternally proceeds from the Father and the Son—has historically been a source of contention between the Western Church and the Eastern Church. While recent efforts to reach ecumenical agreement have claimed to overcome this divide, their proposed solutions not only overlook but overturn the consensus reached by West and East alike at the fifteenth-century Council of Florence, which defined the doctrine and clarified its rootedness in the teaching of the Fathers of the Church.

In Vindicating the Filioque, Thomas Crean, O.P., mounts a robust ecumenical defense of the truth of this doctrine and the authority of its Florentine definition, building his case on principles common to both Catholics and Orthodox. The first part of the study gives a careful presentation of patristic testimony concerning the procession of the Spirit—material central to the conciliar debates at Florence and of abiding theological consequence. In the second part, Crean explores the nature of ecumenical councils, drawing on the first seven councils to establish criteria for conciliar ecumenicity and authority that can be used to evaluate the status of the Council of Florence. The third part describes the Council of Florence itself, showing how it fulfils the criteria for an ecumenical council and replying to objections against its authority.

Combining thorough study of patristic texts, sensitivity to theological common ground, and historical attentiveness to the acta of the council, Vindicating the Filioque demonstrates the soundness of the Florentine definition of the Holy Spirit’s procession and its importance as a basis for lasting unity of East and West.

Fr. Thomas Crean, O.P., holds an S.T.L. from the Institut Saint-Thomas d’Aquin in Toulouse, France, and an S.T.D. from the International Theological Institute in Trumau, Austria. He has published in Augustinianum and New Blackfriars and is the author of several books, including St. Luke’s Gospel: A Commentary for Believers (Arouca, 2021) and, with Alan Fimister, Integralism: A Manual of Political Philosophy (Editiones Scholasticae, 2020). He is a Fellow of the Dialogos Institute and the Albertus Magnus Center for Scholastic Studies and currently lives at St. Dominic’s Priory, London.

“Vindicating the Filioque gives much-needed clarity to the old dispute of the so-called ‘Greek’ and ‘Latin’ traditions regarding the procession of the Holy Spirit. Crean provides an engrossing analysis of a diverse range of Church Fathers on the topic, with a detailed analysis of Greek and Latin theological terms, showing how the teaching of the Fathers stands in relation to the Florentine definition. Examining the concept of ecumenicity embodied by the first seven councils, Crean shows how the Council of Florence meets any criteria accepted at the time by Greeks or Latins, vindicating the infallibility of its definitive teachings on matters of faith. As a Catholic priest of the Byzantine Rite, I consider this book to hold a special importance for rediscovering the theological heritage of the Eastern Catholic Churches and I recognize its important contribution to ecumenical dialogue. The good friar has offered us a clear exposition of ‘fides orthodoxa’ regarding the Procession of the Holy Spirit.”

Rev. Dr. Yosyp Veresh
Greek Catholic Eparchy of Mukachevo