Thomas Aquinas's Summa theologiae

by Bernard McGinn

  Thomas’s treatment of the notion of creation was novel and was attacked from many sides both in his lifetime and afterward. For the “Radical Aristotelians,” like Siger of Brabant, Aristotle and his commentators had rationally demonstrated that the world must be eternal; its existence in time was based on faith. To the traditional theologians who followed Augustine, such as Bonaventure, the temporal existence of the universe was not only taught by scripture, but was also a fact that could be demonstrated by reason. Thomas took his stance between both camps, thereby satisfying neither. For Aquinas, the fact of creation—the notion that the world depended absolutely on God—was a truth of faith, but also something demonstrable by reason. On the other hand, the duration of the universe—whether it was temporal or eternal—was something reason could not decide on its own.

  Thomas’s maneuvering between these opposed positions can be approached through a consideration of four Ds that help clarify his position: dependence, distinction, decision, and duration. The Christian view of “creation from nothing” (creatio ex nihilo) means that the world is totally dependent on God. It always remains, however, distinct from its divine source. Creation also indicates that God creates the world freely by his own decision and that therefore the duration of its existence depends on his will. God decides to make a universe marked by temporality. From the point of view of reason, however, there is nothing impossible in the idea of a universe eternally dependent on God.

  In further elaborating his view of creation, Thomas employs three important distinctions. The first is that creation cannot be thought of according to the Aristotelian concept of change (motus), because change presupposes some underlying reality (a passive potency in Aristotle’s terms), something to be changed, whereas creation has no prior something to be worked on (q. 46.2). Creation is not change; it is the beginning of a relation of absolute dependence (q. 44.1–2). The second distinction is the difference between a natural cause that has to act in a certain way (e.g., fire has to burn) and an intellectual agent, such as God, who acts on the basis of intellect and will (q. 46.1). Furthermore, as the third distinction argues, there is an essential difference between the particular intellectual agents we know and God as the universal intellectual agent, one who not only causes some condition or change, but also causes the total reality of all things in every aspect (qq. 45.2–3, 46.1). Aquinas’s notion of God as the universal creative agent goes far beyond Aristotle’s view of the four kinds of cause (efficient, formal, material, and final), once again revealing his analogical thinking at work.

  Thomas’s theology of creation is an exercise in showing how revelation can use reason while also demonstrating its limits. He draws on Aristotle’s understanding of act and potency, but expands it into his own distinction between existence and essence to demonstrate that God must be absolutely different from the universe: God’s essence is existence, while in all creatures there is a distinction between essence and existence. “Everything that is other than God is not its act of existence, but participates in existence” (q. 44.1). The notion of participation invoked here is crucial in showing the dependence of all things on God. Participation was not prominent in Aristotle’s thought, but was a Platonic category developed by the Neoplatonist philosophers. The Neoplatonists, however, analyzed participation in terms of form; Thomas Aquinas’s universe is a hierarchy of participated existences. Thus, Thomas puts together key themes from the thought of both Aristotle and Plato and his followers in crafting a theology of creation that is different from anything found in the ancient world.12

  Thomas’s treatment of the different kinds of creatures takes up almost half of the Prima Pars (55 of 119 questions). The reason for this extended discussion, especially about human creatures (qq. 74–102), lies in the necessity of understanding our nature and its place in the order of the universe as a way to grasp how to return to God. Here Thomas makes considerable use of Aristotle’s teaching about human nature in general and the soul in particular. It would be a mistake, however, to think of this section of the Prima Pars as a purely philosophical treatise. It is intended to show how sacra doctrina can make use of the truths that reason has explored.

  Thomas’s anthropology has rightly attracted much attention, especially with regard to his epistemology, that is, his account of how human knowing works. It is important to remember that, for all his use of Aristotelian teaching on the soul, his teaching is fundamentally biblical, as can be seen in question 93 on humans as made in the image and likeness of God (Gen. 1:26).13 Because God created man in his image and likeness, there is implanted in both the human intellect and will a tendency toward God as the final end, the true source of blessedness; but, since God’s infinite mode of being surpasses the powers of every creature, this end can be attained only by grace, the supernatural gift by which God freely shares his own divine life. This finality is true of both the intellect’s desire to attain the vision of God’s essence (e.g., q. 12.4) and the will’s desire toward ultimate happiness (e.g., q. 82.2).14 Thomas’s notion of the person as a dynamic intellectual being, for all its Aristotelian elements, is actually nearer to Augustine than it is to Aristotle in its emphasis on the material and historical destiny of each human.15

  How does Thomas conceive of human knowing? Perhaps no aspect of the Dominican’s thought has produced more disagreement. A few issues seem generally agreed upon; others are still contested. For Thomas, because the human intellect exists in a being that is both spiritual and material, “its proper object is an essence (quidditas) or nature existing in a material body” (q. 84.7). Therefore, human knowing begins in the senses and consists of a process whereby the intellect abstracts from, and eventually separates out, material sense knowing in order to gain an abstract idea, or insight, into what a thing is (quid sit), and then to ask whether or not this thing exists (an sit). Attaining truth consists in an identification of the knower and the known (“the understanding in act is the thing understood in act”: q. 87.1, ad 3), as contrasted with knowing conceived of as kind of gazing on truth found in the Platonic tradition (q. 84.1). Thomas employed the analysis of knowing found in Aristotle’s On the Soul (q. 79), especially its distinction between the intellect’s natural capacity to know (the possible intellect) and the active power of questioning that empowers humans to actually arrive at knowledge (the active intellect). For Thomas, however, the active intellect, or light of knowing, is the soul’s created participation in God’s knowing. So while Aquinas made use of Aristotle, his epistemology goes beyond the Greek philosopher’s in important ways. Following Augustine’s introspective analysis of the human subject found in the Confessions and On the Trinity, Thomas attends to the act of understanding as an internal conscious operation (e.g., q. 84.7). While Thomas spends a good deal of time discussing how the concepts that answer the question “What is it?” are formed in the mind by insight, he insists that the goal of understanding is not just forming concepts about things, but the act of judging whether or not these concepts are true. Unfortunately, conceptualist accounts of Thomas’s view of knowing that neglect the importance Thomas accorded to the act of judgment were to be a feature in the Thomist tradition for many centuries.

  The Secunda Pars

  The Secunda Pars, despite its length, has a symphonic consistency,16 featuring as its main theme how humans move toward or away from God through habits and actions. Here Thomas draws on his view of human nature as spiritual-corporeal being as set out in the Prima Pars and expands on it with a meticulous study of human intentionality and action. The Secunda Pars opens with a brief Prologue emphasizing the connection between the first two parts of the Summa rooted in the notion of humans as image of God: “Because … man is said to be made to the image of God insofar as the image is ‘an intellectual being with free choice and in control of its actions,’” declared Thomas, “it now remains to consider his image, i.e., man, insofar as he is the source of his actions, having free choice and control over his actions.” Just as God freely created the universe,
so too humans exercise their freedom by acting according to God’s plan and making their way toward God as the goal of the universe.

  The vast exercise in moral theology that follows is, once again, teleological, based on the question, “What is the purpose of human living?” Other questions that are directed to the goal of life flow from this, such as, “What are the powers and acts that humans share with animals, and what are those that are distinctive of human nature?” “What are habits and how do we distinguish between good and bad habits, that is, virtues and vices?” “What is the difference between virtues that we can gain by our own efforts and those that are God’s gift?” “What is the role of the law given by God in the Old Testament and the grace made available by Christ in the New Testament?” These are some of the larger issues of the Secunda Pars. Embedded within them is a forest of questions and hundreds of articles. We will touch on only a handful below.

  1. The Prima Secundae

  The first five questions of the Prima Secundae are the key for all that comes after, because here Thomas analyzes happiness (beatitudo) as the goal of human freedom.17 All the questions that follow deal with attaining that goal. For Thomas moral theology is based on the search for happiness, not on law or obligation. The Incarnation of the Word in history is the ultimate expression of the divine love that makes it possible for us to reach happiness. This locates Thomas within the tradition of what is called eudaimonistic ethics, in which moral action is determined by its relation to happiness, although there are many forms of eudaimonism.

  Thomas begins by treating the ultimate end of humanity (q. 1.1–8). Properly human actions (actus humanus), as contrasted with those acts humans share with other animals (actus hominis), depend on intellect and will. Although all actions take place in view of some end or purpose, human acts are special, because they are characterized by the choice of the will concerning a goal or end, the good that the agent desires. Thomas argues that our individual choices of good outcomes, when closely analyzed, demand the existence of a single final goal, namely supreme happiness. He dismisses the usual claimants for the status of real happiness (wealth, honors, power, pleasure, etc.), things that—while good in themselves—constitute at best imperfect forms of happiness. Question 3 argues that only the uncreated Good, that is, the divine essence, can be the ultimate happiness humans strive after. As Thomas puts it, “for perfect happiness, it is necessary that the intellect attain to the very essence of the First Cause. And thus it will have its perfection through union with God as its object, in which alone happiness is found.” Although happiness consists essentially in an act of the intellect, it also involves the will insofar as the will reaches the fullness of delight when it attains the final intellectual goal. Everything that comes after this in the Summa exists under the sign of final beatitude—the activities that aid in the journey are good and the actions that impede it are bad.

  A long analysis of human acts follows. Once again, Thomas makes use of the philosophical treatment of human action found in Aristotle, but within the perspective of the relation between nature and grace revealed in sacra doctrina and from the supernatural finality of the desire for the vision of God. In the prologue to question 6 he briefly introduces the rest of the Secunda Pars, saying that he will first treat human acts in general (IaIIae) and then move on to consider human acts in particular (IIaIIae). Concerning human acts in general, he distinguishes between the treatment of acts in themselves (qq. 6–48) and then the consideration of the principles of acts (qq. 49–114). Human acts in themselves can be further divided into acts that are distinctive of humans as possessed of intellect and rational will (qq. 6–21), and the acts that humans share with other animals, that is, the emotions, passiones in Latin (qq. 22–48). After treating the internal principles of acts, that is, powers and habits in questions 49–114, Thomas closes the Prima Secundae with two treatises once again illustrating his program of using Aristotelian thought to help understand revelation. They treat the two major extrinsic principles of human activity as directed to God: first, the instruction God gives to humans through the various forms of law, and then the supernatural gift, or grace, that provides humans with the power they need to attain the goal of the beatific vision. Here we will briefly look at what he says about grace.

  Analysis III. What Is Grace? (IaIIae, 109–14)

  Thomas’s understanding of grace interweaves Aristotle and Augustine under the aegis of what the New Testament, especially Paul, has to say about “the surpassing grace of God that has been given to you” (2 Cor. 9:14). The Dominican took his fundamental stance about the nature and necessity of grace from Augustine, but he drew upon Aristotle’s theory of human action as a form of change (motus), that is, a movement from possibility to actuality, to provide a deeper understanding of the action of grace in the life of the believer. Thomas also argues that grace as the participation in God has a history, so a theology of grace must treat its role in three states: (1) the time of innocence before the Fall, (2) the stage of fallen humanity, and finally (3) grace after the Incarnation.

  Thomas insists that “[t]he gift of grace exceeds every faculty of created nature, since it is nothing else but a kind of participation in the divine nature that exceeds every other nature” (q. 112.1). This is why he uses the term “supernatural” more often in Secunda Pars than elsewhere in the Summa, as when he says that both Adam before the Fall and all humans afterward need a special divine help “to will and to work towards the supernatural good” (q. 109.2). Thomas’s use of the term supernatural was not meant to suggest that we live in some kind of two-story universe, consisting of a natural basement and a supernatural edifice placed on top. For Thomas the universe is one, but there are two ways of conceiving of action within it: acts directed to the good proportionate to our finite created nature, and acts aimed at the final goal of human nature, the eternal vision of God (q. 109.5). The term “supernatural” provided Thomas with a way to talk about God’s action in everyday human life. As he put it later in the Tertia Pars, “The final goal of grace is the uniting of the rational creature to God” (IIIa, q. 7.12).

  The forty-four articles that make up the grace treatise deal with a number of interrelated themes. Some come from scripture and tradition, especially from Paul (as read by Augustine) on the strict necessity of grace. For Thomas, as for Augustine, grace not only was necessary for any saving action, but also was needed for the first movement toward God. Thomas’s reading of Augustine also led him to the conclusion that even the person who has received grace as a habit in the soul needs further grace as an impetus to perform saving actions. To explain this, the Dominican turned to Aristotle and his view of human action in, for example, the way he employs the Philosopher’s notion of habit and human operation to help understand how to talk about grace. Of particular interest in Thomas’s teaching is the care with which he analyzes the relation of the divine and human wills in the process of justification by grace conceived of as both operative (i.e., God alone acts) and cooperative (i.e., where the human will has a role to play).18 Thomas concludes his treatise on grace with a discussion of merit. If salvation depends on God’s free gift, in what sense can humans be said to merit the beatific vision? Thomas answers in terms of a traditional distinction, but with a new twist. Merit, he says, can be considered in two ways: merit is truly earned (ex condigno) insofar as an act really deserves a reward; merit is appropriate (ex congruo) insofar as it is fitting for God in his generosity to reward our efforts even though they are not commensurate with the goal. Saving acts come from two sources for Thomas: from the Holy Spirit as the source of grace, in which case merit is fully earned (ex condigno), and from us as cooperative agents to whom God gives merit as a fitting (ex congruo) reward for our efforts (q. 114.3). Thomas’s treatise on grace is a concise and original example of his theological method.

  2. The Secunda Secundae

  Although grace is never absent from the Summa, its explicit treatment at the end of the Prima Secundae allows Thomas to
make the transition to the Secunda Secundae where he turns from considering human acts in general to acts in particular. Here Thomas is targeting acts insofar as they are salvific, that is, those that proceed from grace as their primary cause, though also involving the human will as cooperating with God. His treatment here is so detailed that all but the most devoted Thomists may be excused from reading the 916 articles that constitute the Secunda Secundae.

  Thomas begins with a Prologue, distinguishing two ways of treating moral matters (moralia): first, from the material in itself, as when we consider a particular virtue or vice; and second, from the perspective of different situations in life that come with their own particular moral obligations. (For example, one can treat the moral obligations that concern everyone separately from the obligations that belong to special groups.) Since virtues and vices consider the same object (e.g., chastity and lust both concern sexual activity), he considers vices along with the virtues they oppose, as well as both positive and negative commandments relating to each. Furthermore, he argues that all the virtues can ultimately be reduced to seven: the three theological virtues of faith, hope, and charity (qq. 1–46),19 and the four cardinal virtues of prudence, justice, fortitude, and temperance (qq. 47–170). A look at his analysis of charity, the most important of the theological virtues, provides a sense of how he proceeds in this section of the Summa.