Daniel Shields

Aquinas' first proof for God's existence is usually interpreted as a metaphysical argument immune to any objections coming from empirical science. Connections to Aquinas' own historical understanding of physics and cosmology are ignored or downplayed. Nature and Nature's God proposes a natural philosophical interpretation of Aquinas' argument more sensitive to the broader context of Aquinas' work and yielding a more historically accurate account of the argument. Paradoxically, the book also shows that, on such an interpretation, Aquinas' argument is not only consistent with modern science, but actually confirmed by the history of science, from classical mechanics through 19th century thermodynamics to contemporary cosmology. The first part of the book considers Aquinas' argument in its historical context, exploring the key principles that everything in motion is moved by something else and that an infinite regress of causes is impossible. The structure of the First Way is analyzed and the argument is connected both with Aquinas' Third Way-a new interpretation of which is also proposed-and Aquinas' second proof from motion in the Summa contra Gentiles. To complete the account of what natural philosophy-prior to metaphysics-can demonstrate about God, a chapter on Aquinas' teleological argument (the Fifth Way) is also included. The second part of the book tracks the history of modern science from Copernicus to today, showing how Aquinas' argument fared at each major turn. The first chapter shows how Newton's understanding of inertia and conservation of momentum supports the idea that motion cannot continue forever without God's causality, and integrates a modern understanding of inertia and gravity with the principles of Thomistic natural philosophy. The second chapter considers the first and second laws of thermodynamics, showing how they too support Aquinas' contention that motion cannot continue forever without God's causality. This chapter also discusses statistical mechanics and contemporary cosmology, demonstrating that science continues to support Aquinas' unmoved mover argument. The final chapter turns to modern biology as well as cosmological fine-tuning to show that modern science also continues to support Aquinas' teleological argument. The result is not only a satisfying defense of Aquinas' natural philosophical proofs for God's existence, but a primer on the broader project of integrating Thomistic natural philosophy with modern science.

One of the standard objections against the impossibility of infinite regress is associated with David Hume and Paul Edwards, but originates with William Ockham. They claim that in an infinite regress every member of the series is explained, and nothing is unexplained. Every member is explained by the one before it, and the series as a whole is nothing over and above its members, and so needs no cause of its own. Utilizing the well-known Thomistic distinction between essentially ordered and accidentally ordered causal series, I show that the Hume-Edwards-Ockham objection fails to touch Aquinas’s argument against the impossibility of infinite regress in an essentially ordered series. However, Aquinas also argues that accidentally ordered causal series can only regress infinitely if supported by an everlasting essential cause. The Hume-Edwards-Ockham objection does raise a question about this thesis, but I show how St. Thomas can reply to it convincingly.

Classical theism is often said to suffer from the problem of modal collapse: if God is necessary and simple then all of his effects (creatures) are also necessary. Many classical theists have turned to extrinsic predication in response: God’s simple and necessary act is compatible with any number of possible effects or no effects, and is only said to be an act of creating in virtue of the existence of the universe itself. Leftow and Schmid criticize this solution for leading to “providential collapse”: God would not have control over which creation obtains if all his intrinsic features are compatible with any possible universe. Thomistic classical theism avoids both modal collapse and providential collapse by utilizing the metaphysics of relations. With no differences within his simple essence/act, God can relate himself differently to his possible effects, willing some and not willing others. These relations determine whether or not the effects will exist. Thomistic classical theism’s version of divine simplicity is not incompatible with God having a multiplicity of relations, for the three divine persons are distinct relations within God. Divine simplicity is only incompatible with a multiplicity of absolute items within God. Furthermore, not all differences of relation are grounded in the different absolute characteristics of their relata. Rather, sometimes differences of relation themselves ground differences in the absolute characteristics of their relata. God’s divine act is thus said to be an act of willing this creation rather than that in virtue of his chosen, contingent relation to possible creatures, rather than in virtue of the creatures themselves.

I argue for a novel reading of the mover principle used in Aquinas’s motion proofs for God’s existence. Many interpret Aquinas’s principle as holding that everything in motion is moved by something else currently in contact with it. Others, following James Weisheipl, understand the principle as claiming only that everything being moved is being moved by something else. I argue against both readings and hold that the principle means that everything in motion is moved by something else—whether that something else simply set it in motion or is currently moving it by contact. By looking closely at Aquinas’s inductive argument for the mover principle, I show that simultaneity between mover and moved is not necessary on Aquinas’s view. My interpretation allows me to respond to objections to Aquinas’s act-potency argument for the mover principle more convincingly than others, and sets the groundwork for robust engagement between Thomism and modern science.

Aquinas holds that by its nature the human will has happiness as its ultimate end in every choice, and yet he holds that one can and ought to love God more than oneself or one’s own happiness. This generates the so-called “problem of love”: how can an eudaimonist like Aquinas account for non-selfish love? I argue that Aquinas’s doctrine of goodness as the will’s object and his distinction between the love of desire and the love of friendship solve this problem and indicate that Aquinas’s eudaimonism is only “subordinated eudaimonism.” By its nature the will has happiness—total inhering goodness—as its ultimate object secundum quid, and God—total subsisting goodness—as ultimate object simpliciter. Nevertheless, Aquinas argues on philosophical grounds and with the support of Aristotle’s Liber de Bona Fortuna that God Himself would have to move the will if one were to love God above oneself even in the order of nature.

Aquinas holds that by its nature the human will has happiness as its ultimate end in every choice, and yet he holds that one can and ought to love God more than oneself or one’s own happiness. This generates the so-called “problem of love”: how can an eudaimonist like Aquinas account for non-selfish love? I argue that Aquinas’s doctrine of goodness as the will’s object and his distinction between the love of desire and the love of friendship solve this problem and indicate that Aquinas’s eudaimonism is only “subordinated eudaimonism.” By its nature the will has happiness—total inhering goodness—as its ultimate object secundum quid, and God—total subsisting goodness—as ultimate object simpliciter. Nevertheless, Aquinas argues on philosophical grounds and with the support of Aristotle’s Liber de Bona Fortuna that God Himself would have to move the will if one were to love God above oneself even in the order of nature.

In this paper I argue that neither St. Bonaventure nor St. Thomas are eudaimonists in the normal sense. Neither holds that happiness--which is a condition of human persons, and thus falls on the creature side of the Creator/creature divide--is the ultimate end of human beings strictly speaking, being rather a penultimate end. God is the true ultimate end of human beings, and He falls on the other side of the Creator/creature divide. Both St. Thomas and St. Bonaventure hold that happiness consists in the attainment of God. They differ in that St. Bonaventure holds that loving God constitutes the attainment of God, for he who loves God has God. St. Thomas, on the other hand, holds that loving God does not in and of itself mean having Him. Love causes us to desire union with God, but is not itself union with Him. God is attained when He is known. However, St. Thomas also holds that loving God is better than knowing Him, and thus better than happiness. This is because God Himself, and not our happiness in knowing Him, is our true ultimate end. On the basis of these theories, both St. Bonaventure and St. Thomas avoid the self-centeredness objections to eudaimonism, while being able to incorporate all of the strengths of virtue ethics.

I argue that, according to St. Thomas Aquinas, God--and not one's own happiness through union with God--is the ultimate end of the moral life strictly speaking. Although He is the source of happiness, God Himself, and not the happiness of knowing Him, is the center of the virtuous agent's life. Thus Aquinas, while incorporating all of the strengths of a virtue ethical framework, is not a eudaimonist in the normal sense, and is thus immune to any self-centeredness objections. I set the stage by contrasting two of Aquinas' explicit and repeated theses. First, he maintains that happiness, strictly speaking, consists in an act of knowledge (the knowledge of God) inhering in the human intellect, rather than in any act of the will. Secondly, he maintains that loving God, an act of the will, is better than knowing Him. This indicates that loving God is better than happiness. By analyzing Aquinas' distinction between the love of friendship and the love of concupiscence, and his distinction between end in the sense of object and end in the sense of attainment, I show that he holds that loving God is better than knowing Him not because the activity of loving God is the ultimate end of the moral life, but because God Himself is the ultimate end of the moral life. Thus man's ultimate end is neither himself nor any condition that He can enter into, but rather a being separate from himself.