On the Eternity of the World: Aristotle, Bonaventure, Aquinas, Kant

Jul 2930, 2020
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Stephen L. BrockPontifical University of the Holy Cross, Rome

This master class is open to current graduate students and uper-level University of Chicago undergraduates. It will take place online via Zoom, in four sessions, over two days. 

Toward the end of his Physics, Aristotle argued that the motion in the physical world, and with it the world itself, never began and will never cease.  Medieval Christian thinkers agreed that this position conflicted with revelation, but they assessed it in a wide variety of ways.  In modernity, Kant used the problem of the world’s duration as evidence of the boundaries of mere reason.  

In this master class, we will go through Aristotle’s arguments, Bonaventure’s rejection of them and insistence that the world’s having begun can be proved, Aquinas’s denial of any possible proof on either side, and Kant’s antinomous “proofs” for both sides.  The readings invite discussion of such topics as the relation between reason and faith, how to understand creation ex nihilo, the relation between physics and metaphysics, and the limits of human knowledge.


  • Wednesday, July 29, 10:00 AM - 11:30 AM; 2:00 PM - 3:30 PM
  • Thursday, July 30, 10:00 AM - 11:30 AM; 2:00 PM - 3:30 PM


  • Aristotle, Physics, VIII.1-2, 250b10-253a21
  • Bonaventure, In II Sent., d. 1, p. 1, a. 1, q. 2
  • Thomas Aquinas, Summa theologiae I, q. 45, aa. 1-2; Summa theologiae I, q. 46; Compendium theologiae ch. 98-99; Summa contra gentiles, II, caps. 31-37; On the Eternity of the World
  • Immanuel Kant, Critique of Pure Reason, Transcendental Dialectic, II.2.2, First Antinomy

Stephen L. Brock is a priest of the Prelature of Opus Dei.  He is Ordinary Professor of Medieval Philosophy at the Pontifical University of the Holy Cross, Rome. He earned a B.A. in Philosophy from the University of Chicago and a PhD in Medieval Studies at the University of Toronto.  Brock writes widely on Thomas Aquinas and action theory, ethics, and metaphysics. He is the author of The Philosophy of Saint Thomas Aquinas. A Sketch (Wipf & Stock, 2015), Action & Conduct: Thomas Aquinas and the Theory of Action (T&T Clark, 1998), and most recently, The Light that Binds: A Study in Thomas Aquinas's Metaphysics of Natural Law (Pickwick Publications, 2020).  He is currently a visiting scholar in the Philosophy Department at the University of Chicago.