Introduction -
Thomas Aquinas posited five proofs for the existence of God in his Summa Theologica, one of the most influential theological philosophy treatises in history. For Aquinas, one need not look beyond the evidence of the natural world to find reasons to believe in God, a presence without which motion, natural design or physical existence itself would be impossible. Aquinas sought to modify many of the rational systems that had been in place for centuries, such as the arguments attributed to Anselm. In his way, Aquinas tried to resolve the mystery of faith with a growing desire to introduce some notion of physical evidence, which he believed could, for instance, be explained by the motion of the stars and planets. Ultimately, Aquinas held that the conditions of being, of corporeal existence, could be ascribed to the direct influence and involvement of a higher intelligence, of a primary mover.
Aquinas’ grounding in Aristotelian science is in evidence in his five proofs. Aristotle wrote of potential and actualization in arguing that “something actual ‘causes’ potentiality to reach another form” (Lander.edu 2005). Francis Bacon insisted that science had been unable to expand on Aristotle’s theories because he too rigidly linked natural philosophy to logic, which alone could not adequately explain the natural world (Lander.edu 2005). Yet Aquinas’ application of Aristotelian logic showed that there was a place for the notion of causality, of how and why natural processes come into being and what animates them.
The Argument from Motion -
The doctrine of the “first mover” underpins Aquinas’ argument from motion. In noting that everything that is in motion was moved by something else, by some external force that caused it to transfer from potentiality to actualization. According to this application of Aristotelian logic, Aquinas concludes that without a primary force that set all things in motion, actualization could not have occurred. And yet many have misunderstood Aquinas’ meaning in this premise, thinking that the first mover had, through physical intervention, initiated a kind of universal domino effect. However, this is an inadequate interpretation of a much larger cosmological proposition. The primary mover was not “temporally prior to the movers that depend on it” (Popkin and Brown 1999, 254). The primary mover transcended restrictions of time and space. “It is above them all and exists simultaneously with them all, somewhat the way that the sun is the cause of the growth of the growth of plants,” which benefits from “secondary causes” that cause the plant to grow and thrive each season (Popkin and Brown 1999, 254).
Thus, the primary mover existed/exists contemporaneously with those objects that it set in motion. In other words, “the idea is that a lower element depends on a higher element as in a hierarchy, not a temporal series” (Lander.edu 2005). There is not a theoretically traceable series or sequence of events that can be followed back to the beginning of the universe. This refutes the possibility of infinity, because an infinite sequence precludes the possibility of a first mover. Rather, subsequent movers move only inasmuch as they are put in motion by the first mover. Therefore, it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God (Aquinas 1921).
Argument from efficient cause -
Aquinas’ second proof also derives from the conception that infinity is an insupportable state. This argument is similar to the argument from motion in that it presupposes the existence of a “first efficient cause.” Aquinas contends that an efficient cause actualized and produced an intermediate cause, which, in turn, produced an ultimate cause (Aquinas 1921). Aquinas explains that “if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false” (Aquinas 1921). Thus, Aquinas concludes, one must allow for a “first efficient cause,” which, he notes, is understood to be God (Aquinas 1921).
This argument has been seen by many as problematic and overly reliant upon Aristotelian reasoning (i.e. logic equals natural philosophy), and considerably weaker than his argument from motion. David Hume, for one, criticizes the efficient cause argument as insufficiently cognizant of the possibility of accident, or the potential for an extensive series of generally occurring states to be the product of a “chance series of occurrences” (Lander.edu 2005). Thus, Aquinas, in developing his second proof, was somewhat too “neat,” too conveniently logical. The possibility of accidental correlation opens the possibility that there could be other factors than causality at work. Another unavoidable problem with Aquinas’ second argument is that the universe is not simply the result of a linear sequence, but instead is a collection of interconnected events that do not necessarily occur sequentially, or unfold chronologically. Infinity, as in Aquinas’ first proof, is the concept that Aquinas is concerned with refuting, the great enigmatic problem of the natural world.
Argument from possibility and necessity -
The third of Aquinas’ proofs is based on the premise that that which exists can only be brought about by something that already exists. Aquinas’ aim here is to show that existence can only have proceeded from existence. “If at one time nothing was in existence, it would have been impossible for anything to have begun to exist; and thus even now nothing would be in existence – which is absurd” (Aquinas 1921). Here again, Aquinas utilizes Aristotelian reasoning to propose a system of sequential causation. This is why Aquinas goes on to claim that every “necessary thing” either is caused by another necessary thing, or it is not. This is reminiscent of the contention in which Aquinas assures us that without a primary mover, nothing could have been set in motion. Infinity is a chief concern of Aquinas’ third proof as well, and he disposes of its possibility in essentially the same way he does efficient cause: If necessary things are caused by other necessary things, then this “sequence” must have had its beginnings in an original cause.
This proposition has been taken up by philosophers and theologians, particularly those concerned with debating the existence of God and the Devil. However, some observers are emphatic in pointing to the fact that Aquinas commits a logical fallacy in his third proof. Aquinas’ use of the word “necessity” presents a problem that is partly semantic in origin. Specifically, necessity is a “property of statements not of objects” (Lander.edu 2005). Thus, it is awkward to claim that a “thing” is logically existent since existent things simply “are,” rather than being intrinsically necessary – in other words, it is not possible for there to be empirical necessities (Lander.edu 2005).
Argument from gradation -
The fourth proof of God’s existence argues that the existence of gradations, or of degrees, is a way of proving that goodness, like any other state of quality, has its highest (and lowest) degree. In other words, “’more’ and ‘less’ are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; so that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being” (Aquinas 1921). Thus, “uttermost being” in this equation represents God, without whom, presumably, there could be no ordering of degrees. The ordering that makes comparison possible, Aquinas tells us, proceeds from a being who represents the “best,” most powerful, wisest, etc., of all gradations.
However, it is possible to counter-argue that making a comparison is not a sufficiently exact argument for proving the existence of God. “It is true that St. Thomas uses the example of a sensible quality (heat) to illustrate his text, but this is only a comparison and not an instance of a perfection” (Elders 1990, 111). In this light, Aquinas contends that God is the source of perfection and, as such, bestowed the gradations of quality upon all that exists. Notions of “better” or “worse” do not, purely speaking, exist in a quantitative sense, “nor is the intensification of sensible qualities meant” (Elders 1990, 111). Ultimately, this argument may well be the most contentious and debatable of Aquinas’ five proofs, in that it is predicated on an argument grounded in inexactitude.
Argument from design –
This is often considered the most influential and well-known of Aquinas’ five proofs. It is often called the argument from “intelligent design,” which proceeds from the idea that because those objects that do not possess the quality of sentient intelligence act “always, or nearly always, in the same way, so as to obtain the best result” (Aquinas 1921). Aquinas argues that if: 1) These objects do not possess intelligence, and; 2) Act, or follow a particular course of action, in ways that are in their best interest; then it follows that they are animated according to some pre-determined plan, set in motion by a guiding intelligence. “Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end” (Aquinas 1921). In a sense, this argument encompasses the other four proofs, all of which depend on the existence and preeminence of an overarching, omniscient and omnipresent entity.
The most pointed, and often-repeated criticism, of this proof is that because there are demonstrable imperfections in the creator’s products, then it must be presupposed that the creator is also imperfect. An imperfect deity is in contravention of the entire arc of Aquinas’ logic, which can be summarized by saying that all things that are caused, moved and designed exist as they are because of an all-powerful and perfect maker. The “imperfection” counter-argument leaves open the possibility of evil (Lander.edu 2005). If there is evil in the design, then there is also sound reason to contend that the designer lacks perfection, that imperfection allowing for the presence and consequences of evil must call into question the very integrity of the intelligent design argument.
Conclusion -
Thomas Aquinas set down a system for seeing and understanding God to be the incontrovertible designer/creator/mover of the universe. Despite the many well-conceived and arguments against his five proofs, Aquinas remains a pivotal figure in the evolution of theological philosophy and the debate over God’s existence. His work is important in that it merges a consideration of the natural world with a justification for faith. In so doing, he brought the rational science of Aristotle to bear against the critics of Christian doctrine. In this, he was so successful that his “version of Christianity became the cornerstone of the philosophical and theological teachings of the Roman Catholic church” (Oppy and Scott 2010, 81). This is the legacy of his vision, as expressed in the monumentally influential 60-volume work, the Summa Theologica.
The most important impact of the Summa Theologica is the remarkably broad and accessible foundation it laid for continuing debate on a subject that is infinite in its scope and infinitely contestable. Thus, it is perhaps more accurate to say that Aquinas established a system for arguing the existence of God rather than establishing a flawlessly logical and unassailable position on the subject. It is this legacy that keeps Aquinas’ philosophy relevant down to the present day.
Works Cited
Aquinas, Thomas. The Summa Theologica. New York: Renziger Bros., 1921.
Elders, Leo J. The Philosophical Theology of St. Thomas Aquinas. Leiden, NK: Brill
Publishing, 1990.
Oppy, Graham and Scott, Michael, eds. Reading Philosophy of Religion. New York: Wiley-
Blackwell, 2010.
Popkin, Richard and Brown, Stephen. The Columbia History of Western Philosophy. New
York: Columbia Univ. Press, 1999.
“Thomas Aquinas: The Five Ways.” Philosophy of Religion, Lander.edu, 2005. Available from:
http://philosophy.lander.edu.
