Two Notions Of The Infinite In Thomas Aquinas’ “Summa Theologiae I, Questions 2 And 46” -- By: Richard G. Howe

Journal: Christian Apologetics Journal
Volume: CAJ 08:1 (Spring 2009)
Article: Two Notions Of The Infinite In Thomas Aquinas’ “Summa Theologiae I, Questions 2 And 46”
Author: Richard G. Howe


Two Notions Of The Infinite In Thomas Aquinas’ “Summa Theologiae I, Questions 2 And 46”

Richard G. Howe, Ph.D.

Near the beginning of his Summa Theologiae, the thirteenth century Dominican monk, Thomas Aquinas, claims that “the existence of God can be proved in five ways.”1 These arguments are regularly referred to as his Five Ways and are for many perhaps the most familiar reading from Thomas. Of particular interest for my purposes are the first three of these Five Ways in which Thomas clearly denies the possibility of “going on to infinity.”2 I have discovered that a number of

philosophy textbooks take this impossibility of going on to infinity as an argument for the impossibility of an infinite regress in the way that the Kalam cosmological argument argues for the impossibility of an infinite regress.3 I contend that this is a misinterpretation of Thomas’ arguments in the Five Ways. Thus, any objections to the Five Ways that are based on objections to the Kalam cosmological argument are entirely misplaced.4

These philosophy texts take Thomas to be arguing in the first three of his Five Ways that the impossibility of an infinite series of motions, efficient causes, or contingent beings implies a first mover, first efficient cause and first necessary being. Several examples will show this common way that philosophy texts take Thomas here. William

F. Lawhead, in his introductory text The Philosophical Journey: An Interactive Approach, says,

Critics have had the most problems with the third premise of Aquinas’s [second way] argument. Why can’t there be an infinite series of causes? Isn’t the series of whole numbers an infinite series?5

Manuel Valasquez, in his introductory text Philosophy: A Text with Readings says regarding Thomas’ second way,

Philosophers have raised two key objections to this cosmological argument. The first concerns its contention that there can be no infinite regress in the causal sequences of the universe. But why not? Isn’t it possible that the universe has simply existed forever and that things in it have simply been moving forever?6

W. T. Jones, in his A History of Western Philosophy: The Medieval Mi...

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