Date of Submission

October 2006


1. Aim of the Thesis. This thesis is concerned to investigate the schemata of metaphysical concepts, and the lines of philosophical argument, used by Thomas Aquinas in reaching conclusions about the nature of the change through which Christ becomes present in the sacrament of the Eucharist, and about the nature of this continuing presence. Although the object to which the thesis relates is provided by doctrinal and theological affirmations, the perspective within which the investigation takes place is that of the reflective rationality distinctive of philosophy. Put differently, the aim of the thesis is to examine the speculative rational work undertaken by Thomas Aquinas in the course of his discussion of issues relating to the change of bread and of wine into the body and blood of Christ in the Eucharist - a discussion that Thomas introduces by first arguing to traditional Catholic belief about the outcome of this change. The examination engages with the reasonable explanatory power of the conceptual resources and the philosophical arguments drawn upon by the Angelic Doctor in his systematic study of the Eucharistic change, and of the implications of this change relative to the continuing presence of Christ in the Eucharist. 2. Scope of the Thesis. The parameters of the thesis are set by St Thomas's discussions of Eucharistic change and presence that take place in part three, questions 75-77, of his Summa Theologiae, book four, chapters 60-68, of his Summa contra Gentiles, and book four, distinctions 10-11, of his Scriptum super Libris Sententiarum Petri Lombardi. Within these parameters are to be included contributions to the issues discussed by St Thomas made by Thomas de Vio Cajetan, Domingo Banez, and Silvester of Ferrara (Ferrariensis), major commentators on the work of Thomas. Extensive presentation, and scrutiny, of opposing arguments from Duns Scotus are also included.;Following an introductory chapter concerned to situate, summarise, and indicate its principal assumptions, the thesis explores what is, for St Thomas, a major objection to affirming the substantially real presence of Christ in the Eucharist: such an affirmation is said to imply the ontological impossibility that Christ's bodily reality is simultaneously present in more than one place. The response to this objection involves an analysis of the distinction between the primary and the secondary formal effects of dimensive quantity, and the use of this distinction to argue at some length that one and the same material thing may be simultaneously present in more than one place if the secondary formal effects of dimensive quantity that would spatially situate this thing in relation to its immediate surroundings are suspended. The thesis then considers three issues dealing with what becomes of the substance of the bread and of the wine at the Eucharistic consecration. In the first of these, Thomas rejects the claim that the substance of the bread and of the wine remains in existence on the altar, affirming that the bread and wine are changed at the level of substance into the body and blood of Christ. This position requires, and receives, sustained treatment of philosophical questions concerning 'substance', and change affecting the whole substance of a thing (within a hylomorphic understanding of material realities). Related problems of individuation, causal agency, and the logic of language that both signifies, and brings about, change, are considered. The second issue investigates the claim that the substance of the bread and of the wine is not changed after all into the body and blood of Christ but is either annihilated or changed into matter-in-an-earlier-state.;This claim is rejected by St Thomas on philosophical grounds, and this section of the thesis engages critically with Cajetan on several points connected with Thomas's arguments The third issue concerns, and affirms, the capacity of bread and wine to be changed substantially into the body and blood of Christ, at which point the thesis widens out to contrast a hylomorphic with a hylomeric account of matter, and to consider at some length Duns Scotus's metaphysics of the Eucharist which oppose those of St Thomas. Chapter six of the thesis explores in some detail the responses of Cajetan and Ferrariensis to the challenges issued by Scotus, and the concluding chapter (chapter seven) provides an analysis of Thomistic ideas regarding three modes of the emergence of being: creation, natural change, transubstantiation. 3. Conclusions. The title asserts that the thesis is 'an examination of the Thomistic metaphysics of the Eucharistic presence'. This examination endorses the following conclusions: 3.1 The schemata of metaphysical concepts employed by St Thomas (e.g. the concepts of substance, accident, esse, primary matter, substantial form, creation, natural change, obediential potentiality, primary/secondary formal effects of dimensive quantity), and his lines of philosophical argument, provide a clearly valid response to 'the exigencies of the inquiring mind at work' in relation to the presence of Christ in the Eucharist. In other words, their reasonable explanatory power is evidently to be affirmed. 3.2 Pari passu the thesis indicates something of what could be called 'the mystery of matter' - the inexhaustible depths and potentialities of matter that the inquiring mind confronts when exploring matter in the distinctive situation that is matter's special dependence on the First Cause in the Eucharistic change (transubstantiation). 3.;3 The thesis is an instance of philosophical work undertaken in the first decade of the 21st century, and within the socio-cultural context of this time. This socio-cultural 'situatedness', although vastly different from the socio-cultural 'situatedness' of Thomas Aquinas, Duns Scotus, Cajetan, Ferrariensis, and Banez, has created no culturally relative barrier - no 'incommensurability' - such as to prevent an understanding of the conceptual/argumentative activity in which these thinkers engaged some centuries ago. Human beings always and everwhere 'fit into' the same Universe through their abiding and ineluctably shared openness to being and its first principles.

Document Type


Access Rights

Open Access


339 pages

Degree Name

Doctor of Philosophy (PhD)


Faculty of Arts and Sciences