Aquinas’s Argument from Design for the Existence of God: Introduction

At long last, we begin the first post on the fifth and final of Aquinas’s Five Ways, or arguments for the existence of God. Outlines of the previous four Ways can be found here, here, here, and here, respectively. The first three, as I’ve explained multiple times previously, are considered Thomistic cosmological arguments. The Fourth Way is really a unique type of argument in its own right, although it certainly has precedent in earlier arguments, including one from Augustine. It also has certain features in common with axiological (moral) arguments, although contains very important differences.

The Fifth Way is commonly categorized as a “Teleological Argument”, or an Argument from Design. Design Arguments have quite a long and impressive history going all the way back to Ancient Greece, to Socrates and perhaps even earlier. The general concept received treatment, at least implicitly, from Plato, Aristotle, some Stoics, and medieval Islamic, Jewish, and Christian philosophers. Modern philosophers such as Newton and Leibniz likewise proposed design arguments. But modern forms of the argument, while perhaps maintaining the same spirit as the classical and medieval versions, underwent somewhat drastic development, particularly in relation to the natural sciences. In fact, contemporary incarnations of the argument are, for the most part, almost entirely dependent upon, and hence most susceptible of criticism by way of, certain interpretations of findings from biology or cosmology. Unfortunately, many who are only familiar with these contemporary design arguments unjustifiably assume that all design arguments are essentially the same and hence guilty of the same or at least similar faults. In this post we will give a brief overview of some different design arguments before introducing Aquinas’s version, which, I think, is not only significantly unique, but also the best of all design arguments, precisely because, in its uniqueness, it does not commit some of the same mistakes as others. Aquinas’s Teleological Argument is, in many ways, more modest than other design arguments, and is somewhat smaller in scope; but is also more fundamental and more defensible.

Before looking at specific design arguments, it might be useful to extrapolate on what I’ve referred to as the “general spirit” behind them. The following is an extremely general and simplistic account, but, I believe, helps get the gist of things. Cosmological arguments tend to ask why certain things exist at all, broadly; they seek a cause or reason behind things. Teleological arguments, in comparison, tend to ask more specifically why certain features of what does exist exhibit certain properties indicative of purpose, intention, or design; they seek an “intelligence” or “mind” behind things. This is, honestly, profound in its own right. It is one thing to think that there is a cause or explanation of things. But to think that there is specifically a mind or a person behind the entirety of the cosmos beggars the imagination. Suddenly everything comes alive with the brilliance and beauty of art or story! Of course, all four of the previous Ways arrive anyways, ultimately, at a personal cause; but the way in which they do so is admittedly more indirect. Design arguments are distinctive in that they illuminate the “marks of mind” in the very structure and nature of the universe itself. A further implication is that not only is there a mind/person behind things, but that the very fundamental nature of reality itself is personal.

Now, before I get ahead of myself, I should point out that I do not think all design arguments are good arguments or even work. In fact, I may not even think that most design arguments work. I’m certainly skeptical of most contemporary versions. What I said above, however, is just to say that I find the very idea of design arguments profound, whether or not any actually turn out to work. The very existence of mind/intelligence/personhood in itself is astounding and awe-inspiring and beyond comprehension. Of course, the natural tendency towards perception of design in nature could be explicable simply in psychological terms. Personal agency seeks personal agency, even inherent in things which are perhaps entirely void thereof. I do think, in that vein, that some design arguments can very much overstep their justifiable bounds; they are, in other words, far too ambitious, over reaching, and indefensible. And yet even these remain, in my mind, interesting and perhaps indicative of something deeper.

With all that having been said, let’s take a look at several different versions of design arguments. From the very beginning of the intellectual project of philosophy there has been a division in fundamental understanding of nature. On one hand are the atomists and materialists with their mechanistic understanding of nature; on the other are the likes of Plato and Aristotle, who argue that nature is actually ordered and intrinsically meaningful. It is the latter who develop design arguments. To explain their understanding of reality being in its very structure ordered, purposeful, and meaningful, they appealed to a great Mind behind it all.

In Plato’s Timaeus, a divine craftsman organizes and informs matter so that physical things become intelligible and ordered. In his Physics Aristotle writes:

“Nature belongs to the class of causes which act for the sake of something . . . Action for an end is present in things which come to be and are by nature . . . Now surely as in intelligent action, so in nature; and as in nature, so it is in each action, if nothing interferes. Now intelligent action is for the sake of an end; therefore the nature of things also is so . . . It is plain that this kind of cause is operative in things which come to be and are by nature . . . It is absurd to suppose that purpose is not present because we do not observe the agent deliberating . . . If, therefore, purpose is present in art, it is present also in nature . . . It is plain then that nature is a cause, a cause that operates for a purpose” [1].

The famous Roman orator, politician, and philosopher Cicero wrote in his De Natura Deorum (On the Nature of the Gods):

“Now of all the things which are administered by nature the universe is, so to speak, the originator, begetter, parent, rearer, and supporter, and it cherishes and contains them as members and parts of itself. But if the parts of the universe are administered by nature, the same must be the case with the universe itself . . . But if all the parts of the universe have been so ordered that they could not have been better adapted for use, or more beautiful as regards appearance, let us see whether they are the work of chance, or whether their arrangement is one in which they could not possibly have been combined except by the guidance of consciousness and the divine providence. If, then, the things achieved by nature are more excellent than those achieved by art, and if art produces nothing without making use of intelligence, nature also ought not to be considered destitute of intelligence. If at the sight of a statue or painted picture you know that art has been employed, and from the distant view of the course of a ship feel sure that it is made to move by art and intelligence, and if you understand on looking at a horologe [clock], whether one marked out with lines, or working by means of water, that the hours are indicated by art and not by chance, with what possible consistency can you suppose that the universe which contains these same products of art, and their constructors, and all things, is destitute of forethought and intelligence?” [2].

This last point is almost an explicit foreshadow of the infamous William Paley “watchmaker” argument almost eighteen hundred years later.

The Stoics likewise believed in a rationally ordered cosmos. The Roman emperor Marcus Aurelius, influenced by Stoicism, wrote in his Meditations:

“That which is from fortune is not separated from nature or without an interweaving and involution with the things which are ordered by Providence. From thence all things flow; and there is besides necessity, and that which is for the advantage of the whole universe, of which thou art a part. But that is good for every part of nature which the nature of the whole brings, and what serves to maintain this nature” [3].

David Hume, though himself a critic of such arguments, presents a summarized formulation of such in his Dialogues:

“Look round the world: contemplate the whole and every part of it: You will find it to be nothing but one great machine, subdivided into an infinite number of lesser machines, which again admit of subdivisions, to a degree beyond what human senses and faculties can trace and explain. All these various machines, and even their most minute parts, are adjusted to each other with an accuracy, which ravishes into admiration all men, who have ever contemplated them. The curious adapting of means to ends, throughout all nature, resembles exactly, though it much exceeds, the productions of human contrivance; of human design, thought, wisdom, and intelligence. Since therefore the effects resemble each other, we are led to infer, by all the rules of analogy, that the causes also resemble; and that the Author of Nature is somewhat similar to the mind of man; though possessed of much larger faculties, proportioned to the grandeur of the work, which he has executed. By this argument a posteriori, and by this argument alone, do we prove at once the existence of a Deity, and his similarity to human mind and intelligence” [4].

Later came the well-known “watchmaker analogy” from William Paley:

“[S]uppose I found a watch upon the ground, and it should be inquired how the watch happened to be in that place, I should hardly think … that, for anything I knew, the watch might have always been there. Yet why should not this answer serve for the watch as well as for [a] stone [that happened to be lying on the ground]?… For this reason, and for no other; namely, that, if the different parts had been differently shaped from what they are, if a different size from what they are, or placed after any other manner, or in any order than that in which they are placed, either no motion at all would have been carried on in the machine, or none which would have answered the use that is now served by it” [5].


“Every indicator of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater and more, and that in a degree which exceeds all computation. I mean that the contrivances of nature surpass the contrivances of art, in the complexity, subtilty, and curiosity of the mechanism; and still more, if possible, do they go beyond them in number and variety; yet in a multitude of cases, are not less evidently mechanical, not less evidently contrivances, not less evidently accommodated to their end, or suited to their office, than are the most perfect productions of human ingenuity” [6].

Philosopher Ed Feser summarizes Paley’s argument:

“Paley’s argument was roughly this: The universe is extremely complex and orderly, like a human artifact, only more so; and while it is theoretically possible that it could have arisen via completely impersonal forces, it is more probable that it was designed by some sort of intelligent being. Paley focuses on living things, their various organs, and their adaptation to their environments as the most powerful evidence of the complexity in question” [7].

Of course, as most critics now point out, these latter points are thrown into question by the discoveries of Darwin. Appearances of design come to be explained in terms of natural processes.

Contemporary design arguments have become more specific and more scientifically involved. Typically these are either biological or cosmological in nature. The former are usually referred to as “intelligent design” arguments and argue from the complexity in biological life. The latter are often referred to as “fine-tuning” arguments and argue from the hyper specificity of fined tuned cosmological constants. For an example of a typical presentation of a Fine Tuning Argument, see this article from philosopher William Lane Craig.

These various arguments have a long history and wide variety of defenses and critiques. What many design arguments have in common is pointing out order and/or complexity in some certain feature of nature and arguing that this order/complexity is only (or more probably) explainable in reference to some Intelligent Agent. Aquinas’s Fifth Way is similar to these in that it does argue to an Intelligent Agent (or, perhaps more precisely, an Agent with intellect), and it does, in a sense, argue from a type of “order”. But, as I shall argue in the following posts, the Fifth Way really does stand out from almost all other teleological arguments. For one thing, Aquinas’s argument from design has a metaphysical depth that is found in almost no other, which is its main strength. For another, the design to which Aquinas appeals is, much more in line with Aristotle, intrinsic rather than extrinsic. In other words, the type of design that Aquinas refers to is intrinsic to the very nature of things, not applied to it externally. This will be explained in further depth in the second part. To conclude this introductory post, I present the fifth way in full as it is given by Aquinas in the Summa Theologiae:

“The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God” [8].



[1]. McKeon, Richard, editor. The Basic Works of Aristotle. New York: Random House, Inc, 1941. Print, 234-235. Quotes scattered throughout Physics 2.8.

[2].Marcus Tullius Cicero. De Natura Deorum (On the Nature of the Gods). Translated by Francis Brooks (London: Methuen, 1896). 3/7/2017. <;. II. XXXIV.

[3]. Marcus Aurelius. Meditations. Written 167 A.C.E. Translated by George Long. Accessed online <;. Book Two.

[4]. David Hume. Dialogues concerning Natural Religion. 1779. Accessed online <;.

[5]. William Paley. Natural Theology: Or Evidences of the Existence and Attributes of the Deity Collected from the Appearances of Nature (Boston: Gould and Lincoln, 1867), 1. Quoted in Kenneth Einar Himma, “Design Arguments for the Existence of God,” Internet Encyclopedia of Philosophy, <;.

[6]. Ibid., 13.

[7]. Feser, Edward. The Last Superstition: A Refutation of the New Atheism. South Bend: St. Augustine’s Press, 2008. ebook.

[8]. Aquinas, Thomas. Summa Theologica. 1265-1274. Trans. Fathers of the English Dominican Province. Coyote Canyon Press, 2010. ebook. I, Q. 2, Art. 3.


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