Totus Tuus Maria You Can Understand Aquinas A Guide to Thomas’ Metaphysical Jargon Matt Fradd and Robert A. Delfino Table of Contents Being and Essence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Substance and Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Necessary and Possible Being . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Substantial and Accidental Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Potentiality and Actuality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Linear and Hierarchical Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Four Causes and Five Ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 The Structure of the Five Ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Reasoning to God’s Existence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Diving Deeper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 So, you want to understand Thomas Aquinas. Good for you! The theology of the Church—to adapt a quotation from Gregory the Great—is like a river, broad and deep, shallow enough here for the lamb to go wading, but deep enough there for the elephant to swim. Aquinas will take you to the broad and deep. Perhaps you’ve tried reading one of his Summa’s in the past only to set it down shortly after picking it up. Don’t worry, you’re not alone. One of the main reasons many modern people fail to stick with Aquinas is that he uses some complex metaphysical terms that they aren’t familiar with. This book exists to introduce you to those terms which, we believe, will make Aquinas much easier to read and understand. So, let’s get underway. Being and Essence You can’t read Aquinas without coming across the term ‘being.’ Of course, all of us use that word in everyday language. We talk about human beings, or, being unable to understand Aquinas! For Aquinas, anything that exists is a being. You, dear awesome person reading this book, are a being. The stone you pick up at the beach is a being, and so is the rainbow you see in the sky. �1 Even the dream you had last night can be called a being, because it existed in your mind. But humans, stones, rainbows, and dreams are different kinds of beings, which leads us to another important philosophical term, ‘essence.’ ‘Essence’ refers to what a being is.1 You, reader, are human. That is your essence. For our purposes in this book, ‘essence’ can also be called ‘nature.’ The traditional definition of human is rational animal. When you understand what a rational animal is then you understand human nature or essence. Animal is the genus, or general category, to which humans belong. As animals, humans are material, living, and sentient beings. But what, traditionally, separates the human species from other species of animal is that humans have the power of reason or intelligence. Essence determines what kind of being something is, for example, human as opposed to feline or canine. Therefore essence limits existence. To be a human—a rational animal—carries with it many limitations. Humans cannot fly in the air like birds, or breathe underwater, like fish. The essence of a thing also determines whether or not it is the kind of thing that can exist on its own or must exist in something else. This leads to our next set of important philosophical terms, ‘substance’ and ‘accident.’ Substance and Accident Suppose, for instance, you meet a person named Mary, who is five feet tall, knows (and teaches) biology, and is the mother of one child. The property of being five feet tall, which we call a 1 Thomas Aquinas, On Being and Essence, trans. Armand Maurer, 2nd rev. ed. (Toronto: Pontifical Institute of Mediaeval Studies, 1968), 30-32. �2 quantity, can only exist in a material being. Similarly, knowledge of biology, which is a quality, can only exist in an intelligent being. Finally, being a mother, which is a relation, only exists for as long as both Mary and her child exists. This is because the relation of being a mother has a foundation in two beings. Quantities, qualities, and relations, though different, are collectively referred to as ‘accidents.’ The essence of an accident—that is, the kind of thing an accident is—is something that must exist in something else. In contrast, it belongs to the essence of a substance not to exist in something else, but by itself.2 So, human, which expresses Mary’s essence, is a substance because it is the kind of thing to which it belongs not to exist in something else, but by itself. Cat is another example of a substance, and so is the metal Gold. While Human, Cat, and Gold are kinds of substances, an individual person, such as Mary, is an example of what we call a primary substance. Mary is a primary substance because she is an actually existing human being, in which accidents, such as knowledge and being five feet tall, exist. Mary has what Aquinas calls real existence, which is existence in the world that exists outside of our minds—the world of mountains and trees, and other people. In contrast, a dream we have during the night only has cognitional or mental existence, for it only exists in our mind. 2 “Since being is not a genus, then being cannot be of itself the essence of either substance or accident. Consequently, the definition of substance is not—‘a being of itself without a subject,’ nor is the definition of accident—‘a being in a subject’; but it belongs to the quiddity or essence of substance ‘to have existence not in a subject’; while it belongs to the quiddity or essence of accident ‘to have existence in a subject.’ Summa theologiae, III, q. 77, a. 1, reply to objection 2. �3 Without real existence we can only think or talk about a substance (or essence) in an abstract way —that is, to the extent we can understand it in our mind. For example, Tyrannosaurus Rex is a kind of substance—a large, bipedal, carnivorous dinosaur. But this is an example of an essence that does not have real existence. Although we have some understanding of its essence from studying its fossils, these dinosaurs no longer exist and have been extinct for millions of years. So, to sum up, this human (Mary) or this cat (Fluffy) refers to a primary substance; whereas Cat or Human is what we call ‘secondary substance,’ which is related to the essence of a thing. While it might be tempting to think that God is the most primary substance of them all, that would be incorrect. God is not a primary substance.3 This is because, a substance always refers to some kind of essence, such as Human or Cat, to which it belongs not to exist in something else, but by itself.4 However, after the five ways, Aquinas argues that God does not have an essence that limits His Being.5 Instead, he argues that God’s existence is identical to His essence.6 This leads to an important distinction between ‘necessary being’ and ‘possible being.’ 3 “A substance is a thing to which it belongs to be not in a subject. The name thing takes its origin from the quiddity [the essence], just as the name being comes from to be [to exist]. In this way, the definition of substance is understood as that which has a quiddity to which it belongs to be not in another. Now, this is not appropriate to God, for He has no quiddity save His being. In no way, then, is God in the genus of substance.” Summa contra gentiles, Book I, chapter 25, paragraph 10; trans. Anton C. Pegis, in Saint Thomas Aquinas, Summa Contra Gentiles: Book One God (University of Notre Dame Press, 1975), 128. 4 “The word substance signifies not only what exists of itself … but, it also signifies an essence that has the property of existing in this way—namely, of existing of itself; this existence, however, is not its essence.” Summa theologiae, I, q. 3, a. 5, reply to objection 1. 5 ST, I, q. 3, a. 4. 6 He expresses this by saying “it is impossible that in God His existence should differ from His essence.” ST, I, q. 3, a. 4. �4 Necessary and Possible Being The description Aquinas uses to refer to God is Subsistent Being Itself (Ipsum Esse Subsistens).7 Let’s examine this description more closely. God is appropriately called Being, because, as mentioned earlier, anything that exists is a being. But unlike Mary, whose human essence limits her being, God does not have an essence that limits His being. This means that God is Being Itself, not human being, or feline being. Finally, we use the term ‘subsistent’ to describe a being that is capable of existing, not in another, but by itself. Because Being Itself does not exist in anything else, God is Subsistent, which completes the description ‘Subsistent Being Itself.’ If Aquinas is correct that God is Subsistent Being Itself then God exists necessarily. In other words, God is a Necessary Being, which means it is impossible for God not to exist. There are two reasons for this. First, as Being Itself, God does not require a cause to give Him Being because He is Being. Second, as Being Itself, God does not have an essence that can lose its existence, as in the case of the essence Tyrannosaurs Rex, which no longer has real existence. When it is possible for a being to exist or not exist, Aquinas calls it a possible being. Possible beings are also called contingent beings, because their existence is dependent on a cause. Indeed, one of the ways Aquinas argues to God’s existence is through the contingent existence of possible beings. To put it very simply, if the universe and all the beings in it have being contingently then 7 ST, I, q. 4, a. 2, and q. 11, a. 4. �5 they must rely on a cause for their existence. And this cause must be a non-contingent or necessary being. One way we become aware of contingent existence is through the fact that primary substances undergo different kinds of change. Let’s consider that next. Substantial and Accidental Change Over time, a primary substance, such as Mary, will undergo change. Some of these changes will be in quantity, quality, and relation, and therefore they are called accidental changes. For example, growing in height, learning something new, and becoming a mother are all accidental changes. These kinds of changes make Mary exist in a new way, but do not change Mary’s essence, for Mary remains a human being throughout all of them. However, as we will discuss below and in the dialogue, Aquinas will argue that a cause external to Mary is required to explain how she exists in a new way when she acquires a new accidental property. Not all changes are accidental, however. Some kinds of changes are substantial, as when Mary dies, for example. Mary is a rational animal—a living substance—but upon death her bodily remains are no longer a living substance. Another example of a substantial change would be when scientists convert one substance, such as bismuth (a metallic element next to lead on the periodic table), into a different substance, such as gold. This can (and has been) done in particle �6