By Cee Vee
Often referred to as the ‘teleological argument’, or argument from design, Thomas Aquinas’ Fifth Way sets itself apart from Aquinas’ other four proofs for the existence of God. While the other four proofs have their own merits by showing God as a necessary, unmoved mover, uncaused cause outside of time, space, and matter, the Fifth Way is a succinct yet bold case for God as creator and governor of the universe. In short, Aquinas claims that because the universe is intelligible, there must be an intelligent being that directs all natural means to their respective end goals (459).
Still, despite the Fifth Way persisting as a popular proof and influencing modern spin-offs of intelligent design theories, it has its fair share of critics. As such, it is important to understand the various sides to the argument. This paper explores the positions both for and against the Fifth Way, though it also proposes that two arguments for the proof – the Finality Argument and the Shortcut Argument (Hayes 219) – are among the strongest and most compelling.
Before delving into the arguments for and against the Fifth way, it is first necessary to understand the crux of the proof and how it has been framed in both philosophical and modern scientific terms. The proof itself, as Aquinas explains, involves observing the natural world and order of things; and from these observations, humans can see that natural bodies “act for an end.” Thus, natural bodies have a designed means to achieve the end; an intelligent being is in charge of directing them — just as an “arrow is directed by the archer” (459).
Building on the archer analogy, Owens describes a bystander who sees a target on a wall: Suddenly arrows fly from behind the bystander, and a majority of the arrows hit the target. The idea is that nature, or some purely biological method, is not driving the arrows; rather, an intelligent being is directing the arrows to their end goal or toward a greater good: “Something is in play that believes that hitting the target is better than not hitting it, and which is obviously trying to achieve the best outcomes” (728).
In other words, the Fifth Way, also known as the “Proof from the Governance of Things,” suggests that it is God who governs all things, animate or inanimate, towards specific ends. For instance, humans, as sentient beings, are provided with a governed path to achieve good. And while not all natural bodies are conscious, Aquinas’ point is that all things made of matter are intelligible and thereby function as something that can be traced back to God as the supreme designer (Hayes 216).
However, just because natural bodies are intelligible, does not mean that they all have a one-to-one purpose to benefit humankind. Here on Earth, it appears that the rest of creation, animate or inanimate, caters to humans, who continually harvest an ever-flowing abundance of natural resources, form or rule relationships involving other life forms, and have the advanced cognitive ability to create technological marvels. Humans are so fortunate in these ways, that the world seems custom made specifically for humans — or what is called the ‘anthropocentric view’ (Hayes 217). Yet this view is not meant to be axiomatically scientific, else it opens the door for critics to use the ‘puddle analogy’ to ridicule the argument: “I (the puddle) fit in this pothole so perfectly, this pothole must have been created specifically for me!” (Hayes 217).
To overcome initial biases about the Fifth Way, two arguments for the proof, the Finality Argument and the Shortcut Argument bolster the foundational understanding. Somewhat based on Aquinas’ Second Way, which suggests there must be a first cause to generate efficient causes and their ultimate effects (458), the Finality Argument claims that intelligible things have causal explanations. Philosophers may point out that if efficient causality (Second Way) already correlates with a first cause, a ‘final cause’ (the Finality Argument) may lead to a “multiple causes beyond necessity” situation (Hayes 218). However, using the relationship between a flame and heat as an analogy, Hayes describes the flame as the efficient cause of heat and which directs a certain effect — that is, a ‘finality’ (218).
Yet the Finality Argument is a more of a setup for the more compelling argument — that is, the ‘Shortcut Argument’, as Hayes calls it. The core claim is as follows: The universe is intelligible; causality is infused with creation / all intelligible things. And because all things have a sufficient cause, they move from potentiality to action. Further, if it were possible for potential to move to action without a sufficient cause, the universe would therefore be unintelligible (219).
One way to test the Shortcut Argument is to address three propositions: A.) The universe has no cause or explanation. B.) Order within the universe is a cosmic accident. C.) An intelligent designer is responsible for all order within the universe. Keeping with the Shortcut Argument’s claim that all natural bodies are intelligible, the first two propositions cannot be true. Here is why: if the universe / all natural bodies have no explanation, then they are unintelligible. Moreover, if any natural body does not have a causal explanation, albeit that causality is key to intelligibility, then the universe cannot be intelligible. Additionally, why would causality be valid at all if the principle is essentially violating itself (Hayes 220, 221)?
In other words, a self-refuting proposition is just that — self-refuting. If there is no logical basis for a principle, then the principle is an empty word or phrase; it has no intrinsic meaning or truth to it. It remains — unintelligible. But considering that the natural world, the entirety of the universe, has an order, it is inherently intelligible. And because it is intelligible, the third proposition (an intelligent designer is responsible for the order) remains on the table.
That is not to say that the Fifth Way is immune to flaws or counterarguments. From an evolutionary biology perspective, blind selection in nature has spawned various types of organisms. Consequently, Aquinas’ claim that things acting in a means-causing-an-end manner must explain why, say, blind selection may achieve an end for a greater good, or that its “action is for the best” (Owens 729).
In addition, some skeptics of the Fifth Way may want to know why things within a created order cannot have their own, undirected systems as part of their typical function. Why does an intelligent designer need to be involved? Is the Fifth Way simply a Medieval form of the ‘God of the Gaps’ problem pointed out by modern skeptics of the teleological argument (Owens 730, Newton 569)?
Speaking of which, modern arguments for teleology come with their own challenges. For instance, Michael Behe’s claims about ‘irreducible complexity’ in the universe — that all organisms are too complex to have “evolved by chance and natural selection’ — is drastically different from evolutionary biology, which asserts that natural selection is core to how organisms have developed and adapted over time, including that organisms perfect themselves by adopting functions that benefit their survival (Newton 570, 571).
Nevertheless, Aquinas’ Fifth Way is not meant to be a deep analysis of scientific inquiry. It is a philosophical claim about creation’s causal relationship with its Creator. Keeping to the philosophical approach, there are still other criticisms to consider. Decker, who disagrees with Hayes’ use of the Finality and Shortcut arguments to support Aquinas’ Fifth Way, has key objections to Hayes’ claims. First, while Hayes sees a plausible link between order in the universe and an intelligent designer, Decker finds it a bit odd for a divine being to create a universe that is supposedly 99% not conducive to human life (241, 242). Note: The word “supposedly” is not meant to deny that known parts of the universe may not be conducive to human life, but that much of the universe overall has yet to be fully explored.
Decker also chips away at Hayes’ reliance on sufficient reason and the universe as intelligible, as well as whether Hayes is dressing up the ‘God of the gaps’ problem in new clothes (so to speak). Decker explains that while sufficient reason can help explain foundations for systems, science is not so concerned about the foundations; it instead wants to “bridge gaps between multiple packages of internally coherent laws” (242). Furthermore, as Decker views the Fifth Way as an assumption and not quite a proof, Decker wants an empirical, heavily science-based answer for why humans, who can identify intelligibility, have unintelligible gaps in knowledge, such as the gap between quantum mechanics and general relativity (243).
In response, Hayes and others give a more holistic view of Aquinas’ Fifth way, and not to relegate it to purely science-based conversation. Granted, science is still necessary to the conversation — but because Aquinas’ Fifth Way was proposed centuries before the modern scientific method, the conversation remains a philosophical one as well (Hayes 224). Still, the fact that the scientific method is now a staple in modern society demonstrates a need to understand order within the universe. Once again, this makes the case for the universe as intelligible and therefore open to an intelligent designer (Hayes 215).
Also, when Aquinas refers to natural bodies, he is not necessarily referring to biological variance. Aquinas’ overarching point about natural order is that it clearly has behaviors: “Tides go in and out, flames rise, and bodies fall.” Meaning that if there were no intelligent behaviors or patterns, science would have no means to gather empirical data (Hayes 225).
Furthermore, when considering God as a governor of all creation, the Fifth Way suggests governance as a goal and not only an outcome. Owens uses a volcanic eruption as an analogy: Although the cloud that rises from the eruption may be strikingly beautiful, and this pattern may be typical, the eruption itself does not aim for the cloud as the end goal, or that it specifically intends to create a mountain. Rather, the Fifth Way is “as if the central move is a kind of waking up to what was always necessarily the case, though it might not have been apparent to us” (732, 735).
Overall, the Fifth Way suggests a driving force behind the natural order of all things, while the natural bodies themselves, animate or inanimate, have necessary end goals. Just as an apple tree orders itself to produce apples, yet the apples are not present until the tree causes the action, God knows the final cause of things because “for a cause to exert causal power, it must be present in some way” (Owens 572).
Lastly, because Aquinas’ Fifth Way asks “whether God exists” and not about the probability of God’s existence, Aquinas’ premises and conclusion, based on metaphysical proofs, are still valid. That is, again, if the universe is intelligible, and causality is not self-refuting, unless science itself is denied, the conclusion remains strongly plausible and consistent (Hayes, 237).
Works Cited
Aquinas. Summa Theologica. Edited by Pojman, Louis, and Lewis Vaughn, Classics of Philosophy. 3rd ed. New York: Oxford University Press, 2011.
Decker, Kevin S. “A Response to Hayes.” Value Inquiry Book Series, vol. 289, Feb. 2016, pp. 241–44
Hayes, Michael. “Aquinas’ Fifth Way and the Possibility of Science.” Value Inquiry Book Series, vol. 289, Feb. 2016, pp. 215–26.
Hayes, Michael. “A Response to Decker.” Value Inquiry Book Series, vol. 289, Feb. 2016, pp. 237–40
Newton, William. “A Case of Mistaken Identity: Aquinas’s Fifth Way and Arguments of Intelligent Design.” New Blackfriars, vol. 95, no. 1059, Sept. 2014, pp. 569–78.
Owens, John. “Aquinas’ Fifth Way.” New Blackfriars, vol. 101, no. 1096, Nov. 2020, pp. 726–39.