Five proofs of the existence of God, Edward Feser. Introduction.

 This is not a book about Saint Thomas Aquinas’ Five Ways.1 Some readers of my earlier books might have supposed otherwise, given that I have defended Aquinas’ arguments elsewhere and that the title of this book is Five Proofs of the Existence of God. But though there is certainly some overlap with what Aquinas says and with what I have said in other places, this book stakes out somewhat different ground. It is not new ground, exactly, insofar as none of the proofs I will discuss is original with me. But it is different ground insofar as several of these proofs are arguments I have not previously defended at any length. It is also different in that most of these proofs have not received much attention in contemporary philosophy. This is remarkable, given that they have been very prominent historically, and given that they happen to be the most powerful arguments for God’s existence on offer (or so I think). My longtime readers will not be surprised when I say that in my view this tells you nothing about the proofs themselves and everything about the state of contemporary academic philosophy, including philosophy of religion. Though the arguments are not new in themselves, then, they will be new to most readers, as will much of what I have to say in defense of them. What is distinctive about this book will perhaps be most easily explained by saying something about its origins. In my earlier books The Last Superstition and Aquinas, and elsewhere, I approached questions of natural theology—that is to say, questions about what might be known via unaided human reason, apart from divine revelation, concerning the existence and nature of God and of his relationship to the world—by way of exposition and defense of what Aquinas had to say on the subject.2 Since Aquinas is, in my estimation, the greatest of natural theologians, that approach has its advantages. But it has its limitations too. For one thing, it requires that the discussion be largely exegetical, a matter of explaining what Aquinas meant to say, or at most the direction in which his arguments could be taken (and have been taken by later Thomists), given what is actually to be found in his texts.3 That in turn requires setting out the background philosophical principles concerning the nature of change, causality, contingency, and so forth, that are deployed in his arguments; disentangling the essential ideas from the contingent and erroneous scientific assumptions in terms of which he sometimes expresses them; and so on. It is for that reason that, in both of the books mentioned, the reader has to work through seventy pages of sometimes dense general metaphysics before questions of natural theology are addressed. For another thing, the approach requires confining oneself to the arguments that Aquinas himself happened to think are the most significant ones. In the years since those books appeared, though, it has occurred to me that there is a place, indeed a need, for a book that approaches things differently. In particular, there is a need for an exposition and defense of certain important arguments for God’s existence that Aquinas himself does not discuss and which have also received insufficient attention in recent work in natural theology. And there is a need for an exposition and defense of all of the most important arguments for God’s existence that is neither burdened with complex and often tedious issues of textual exegesis, nor preceded by any detailed metaphysical prolegomenon, but which simply gets straight to the heart of the arguments and introduces any needed background metaphysical principles along the way. That is exactly what the present book does. Two of the proofs I defend here can be found in Aquinas, but three of them are not arguments that Aquinas discusses, at least not at length or in the form presented here. Nor is there any exegesis in this book, of Aquinas’ texts or those of any other great thinker of the past. To be sure, and as the table of contents suggests, the arguments are all certainly inspired by several great thinkers of the past —in particular, by Aristotle, Plotinus, Augustine, Aquinas, and Leibniz. Indeed, I think that the proofs that I defend here capture what is essential to the arguments of these thinkers. But I am not presenting an interpretation of any text to be found in the writings of any of these thinkers, and I am not claiming that any of these thinkers said or would agree with everything I have to say. I defend an Aristotelian proof of God’s existence, but not Aristotle’s own proof, exactly; an Augustinian proof, but not an exegesis of anything Augustine himself actually wrote; and so forth. And I do not set out any more in the way of background metaphysics than is absolutely necessary before getting into the proofs. As far I am able, I introduce the relevant background metaphysical principles along the way, in the course of their application to natural theology. Each of the first five chapters of the book is devoted to one of the proofs, and each of these chapters has the following structure. First, I present what I characterize as an informal statement of the argument, in two stages. In stage I, I argue for the existence of something fitting a certain key description, such as (for example) the description “an uncaused cause of the existence of things”. In stage 2, I argue that anything fitting the description in question must have certain key divine attributes, such as unity, eternity, immateriality, omnipotence, omniscience, and perfect goodness. These presentations are “informal” in the sense that the arguments are not initially set out in the explicit step-by-step format beloved of contemporary analytic philosophers, but rather in a more discursive and leisurely way. The reasons for this procedure are that I want to make it as easy as possible for readers unfamiliar with philosophy to get into and understand the arguments, and also that I need at various points temporarily to digress into more general issues of metaphysics so as to make clear exactly what is going on in the proofs and to forestall potential misunderstandings or irrelevant objections. To be sure, the discussion does at times get pretty technical. But the aim, in the earlier parts of each of these chapters, is to introduce the reader to these technicalities as gently as is feasible. I want the book to be of interest not only to academic philosophers, but also, as far as possible, to laymen who are willing and able to get into philosophical abstractions if they are given the chance to ease into them gradually. Though we end up, in every chapter, in the deepest part of the deep end of the pool, I always try to start at the shallowest part of the shallow end that I can. (As the reader will discover, this is easier to do with some arguments than with others.) The next section of each of these chapters contains what I characterize as a more formal statement of the argument. Here I do set out the arguments in an explicit step-by-step manner, with the aim of making the logical structure of the reasoning as evident as possible, and of recapitulating in a crisp and clear way the line of thought that the reader will have worked through in a more informal and leisurely way in the preceding discussion. None of these more formal sections is meant to stand alone. The reader may not understand them properly if he has not first read the more informal sections that precede them, which slowly and carefully explain the significance of each of the key concepts deployed in the more formal statement. But the more formal statement should make it clear in each case how everything said in the more informal preceding discussion ties together. Finally, each of these chapters concludes with a long section addressing various objections which have been or might be raised against the argument developed in the chapter. These sections are in some cases where the most technical material appears. More specifically, the content of each of these first five chapters is as follows. Chapter ι defends what I call the Aristotelian proof of the existence of God. It begins with the fact that there is real change in the world, analyzes change as the actualization of potential, and argues that no potential could be actualized at all unless there is something which can actualize without itself being actualized—a “purely actual actualizer” or Unmoved Mover, as Aristotle characterized God. Aristotle developed an argument of this sort in book 8 of his Physics and book 12 of his Metaphysics. Later Aristotelians such as Maimonides and Aquinas developed their own versions—the first of Aquinas’ Five Ways being one statement of such an argument. These earlier writers expressed the argument in terms of archaic scientific notions such as the movement of the heavenly spheres, but as modern Aristotelians have shown, the essential kernel of the argument in no way depends on this outdated husk. Chapter I aims to present the core idea of the argument as it might be developed by an Aristotle, Maimonides, or Aquinas were they writing today. Chapter 2 defends what I call the Neo-Platonic proof of God’s existence. It begins with the fact that the things of our experience are in various ways composite or made up of parts, and argues that the ultimate cause of such things can only be something which is absolutely simple or noncomposite, what Plotinus called “the One”. The core idea of such an argument can be found in Plotinus’ Enneads, and Aquinas gave expression to it as well. Indeed, the notion of divine simplicity is absolutely central to the classical theist conception of God, though strangely neglected by contemporary writers on natural theology, theists no less than atheists. Among the aims of this book is to help restore it to its proper place. Chapter 3 defends an Augustinian proof of God’s existence. It begins by arguing that universals (redness, humanness, triangularity, etc.), propositions, possibilities, and other abstract objects are in some sense real, but rejects Plato’s conception of such objects as existing in a “third realm” distinct from any mind and distinct from the world of particular things. The only possible ultimate ground of these objects, the argument concludes, is a divine intellect—the mind of God. This idea too has its roots in Neo- Platonic thought, was central to Saint Augustine’s understanding of God, and was defended by Leibniz as well. This book puts forward a more detailed and systematic statement of the argument than (as far as I know) has been attempted before. Chapter 4 defends the Thomistic proof of God’s existence. It begins by arguing that for any of the contingent things of our experience, there is a real distinction between its essence (what the thing is) and its existence (the fact that it is). It then argues that nothing in which there is such a real distinction could exist even for an instant unless caused to exist by something in which there is no such distinction, something the very essence of which just is existence, and which can therefore impart existence without having to receive it—an uncaused cause of the existence of things. Aquinas presented an argument of this sort in his little book On Being and Essence, and many Thomists have regarded it as the paradigmatically Thomistic argument for God’s existence. Chapter 5 defends a rationalist proof of the existence of God. The proof begins with a defense of the principle of sufficient reason (PSR), according to which everything is intelligible or has an explanation for why it exists and has the attributes it has. It then argues that there cannot be an explanation of the existence of any of the contingent things of our experience unless there is a necessary being, the existence of which is explained by its own nature. This sort of argument is famously associated with Leibniz, but the version of it I defend departs from Leibniz in several ways and interprets the key ideas in an Aristotelian-Thomistic way. (Hence, while it is definitely “rationalist” insofar as it is committed to a version of PSR and to the thesis that the world is intelligible through and through, it is not “rationalist” in other common senses of that term. For example, it is in no way committed to the doctrine of innate ideas or other aspects of the epistemology associated with continental rationalist philosophers like Descartes, Spinoza, and Leibniz. And its interpretation of PSR differs in key respects from theirs.) Having presented these five proofs of God’s existence, I move on in chapter 6 to examine God’s nature and the nature of his relationship to the world of which he is the cause. These issues will already have been addressed to a considerable extent in the preceding chapters, but chapter 6 examines them in greater depth and more systematically. It begins with exposition and defense of three key background principles: the principle of proportionate causality, according to which whatever is in an effect must in some sense preexist in its total cause; the principle agere sequitur esse, according to which the way a thing behaves or operates follows from what it is; and the Thomist account of the analogical use of language. It then deploys these principles, first, in deriving the various divine attributes and addressing philosophical questions and objections that have been raised visà-vis these attributes. The chapter shows, to start with, that it is one and the same God at which each of the five proofs arrives, and that there can in principle only be one God. Having thereby established God’s unity, the chapter goes on to show that to God we must also attribute simplicity, immutability, immateriality, incorporeality, eternity, necessity, omnipotence, omniscience, perfect goodness, will, love, and incomprehensibility. The chapter then expounds and defends the doctrine of divine conservation, according to which the world could not exist even for an instant if God were not continually sustaining it in being; and the doctrine of divine concurrence, according to which no created thing could have any causal efficacy if God were not imparting causal power to it at any moment at which it acts. Along the way it is shown that these and other arguments rule out conceptions of God’s relationship to the world such as pantheism, panentheism, occasionalism, and deism. Chapter 6 ends with a discussion of what a miracle is and the sense in which God might cause miracles. (Those issues, as the reader will see, are crucial to determining whether there could be a source of knowledge about God outside of natural theology, in some special divine revelation—though whether any such revelation has occurred is a question beyond the scope of this book.) Finally, chapter 7 addresses various criticisms of natural theology. These too will already have been dealt with to a considerable extent in the preceding chapters, but the aim of chapter 7 is both to address some objections not considered in earlier chapters, and to examine in even greater depth some of the objections that were considered in the earlier chapters. By the end of the chapter, and thus the end of the book, it will be clear that none of the objections against arguments of the sort defended in this book succeeds, and indeed that the most common objections are staggeringly feeble and overrated. That is a confident claim, I realize. But natural theology, historically, was a confident discipline. A long line of thinkers from the beginnings of Western thought down to the present day—Aristotelians, Neo-Platonists, Thomists and other Scholastics, early modern rationalists, and philosophers of some other schools too, whether pagans, Jews, Christians, Muslims, or philosophical theists—have affirmed that God’s existence can be rationally demonstrated by purely philosophical arguments. The aim of this book is to show that they were right, that what long was the mainstream position in Western thought ought to be the mainstream position again. The real debate is not between atheism and theism. The real debate is between theists of different stripes—Jews, Christians, Muslims, Hindus, purely philosophical theists, and so forth—and begins where natural theology leaves off. This book does not enter into, much less settle, that latter debate. I will be satisfied if it contributes to getting us back to the point from which the deepest questions can be addressed.