Joseph Magee

In the Third of his celebrated Five Ways in Summa Theologiae Ia, q. 2, a. 3, St. Thomas Aquinas argues for the existence of God from contingency and necessity noting that the world contains possible beings which are able not to be since, being generated and corrupted, they at some time do not exist. He claims to show that there must be some necessary being since it is impossible that all things are possible beings. Scholars have long found this part of the Third Way problematic, since it appears that Aquinas is committing a logical fallacy. He seems to be arguing that all members of a group have one common attribute since they each have their own particular instance of that attribute, as one might argue that since everybody has a birthday, i.e., one day on which each was born, therefore, there is one (and the same) day on which everyone was born. This paper will show that the accusation that Aquinas commits the alleged Birthday Fallacy would mean he was arguing for a temporal beginning for all material things, and so believed that such claim was philosophically demonstrable. Aquinas, however, argued against our ability to naturally know physical creation had a beginning in time; such knowledge requires God’s revelation of it. Instead Aquinas in the Third Way is allowing for the possibility that the physical universe could be temporally infinite, as Aristotle argued, but that this possibility would still support Aquinas’ contention that some necessary being must exist.

After presenting the “first and more manifest way” of proving the existence of God by reason alone in Summa Theologiae Ia, 2, 3, Saint Thomas Aquinas continues this project by turning in the “Second Way” to what he somewhat enigmatically calls “the nature of the efficient cause.” The greatest obstacle to understanding his Second Way, though, is determining precisely what Aquinas means by “the nature of the efficient cause” and “an order of efficient causes,” and how the Second Way is distinct from the First and Third Ways. This paper shows that instead of purporting to demonstrate God's existence as the cause of metaphysical being, as is commonly supposed, Aquinas is actually searching for the ultimate cause of immanent activity in rational beings. It argues for this reading both from textual evidence internal to the Second Way and in the First Way.

Amid the ongoing debate over the proper interpretation of Aristotle's theory of sense perception in the "De Anima," Steven Everson has recently presented a well-documented and ambitious treatment of the issue, arguing in favor of Richard Sorabji's controversial position that sense organs literally take on the qualities of their proper objects. Against the interpretation of M. F. Burnyeat, Everson and others make a compelling case the Aristotelian account of sensation requires some physical process to occur in sense organs. A detailed examination of the interpretation by Everson and Sorabji of Aristotle's theory, however, shows that their reading cannot be the correct one, since it involves many textual and philosophical difficulties. Their interpretation, for instance, would require abandoning Aristotle's requirement that only a transparent substance is suitable matter for an eye. Likewise, their understanding of the Aristotle's doctrine of sensation as the reception of form without matter in "DA 2.12" cannot be reconciled with other texts of his from "On Generation and Corruption." An analysis of these texts, as well as "DA 2.7" and "De Sensu 6" on the roles of light and the transparent medium in vision, show that, for Aristotle, the physical processes which sense organs undergo are not standard qualitative changes (i.e. alterations), but activities or the actualizations of potencies in the material constituents of living animal bodies.