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Notes on Finality in Aquinas’s Fifth Way

Published online by Cambridge University Press:  05 April 2024

Peter Weigel Open the ORCID record for Peter Weigel [Opens in a new window]
Peter Weigel*
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Department of Philosophy and Religion, Washington College, Chestertown, MD, USA
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Abstract

Aquinas’s Fifth Way argues for God’s existence from the perception of goal-directed activity in nature. Its details are difficult to understand. This study interprets the premises and offers background reasoning for them, which Aquinas develops elsewhere in his writings. A major focus is clarifying the scope of finality the Fifth Way invokes. The argument leaves unspecified the kinds of purposive activity in nature Aquinas has in mind. Thus, the discussion first treats types of purposive activity in nature Aquinas recognizes. It then looks at the two reasons the argument gives for final causes in nature. Things tend to act in regular ways and tend toward what is ‘best’. Attention then turns to the key premise that goal-directed activity in nonrational beings requires direction by something with intelligence. A final section of the article explores why Aquinas seems to look to a single source of finality in nature and why, in the conclusion, he claims that we call this God. Thus, Aquinas’s larger views on finality in nature shed light on his intents in the Fifth Way.

Keywords

AquinasFifth WayFive WaysGod’s existenceteleological argument
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Article
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New Blackfriars , First View , pp. 1 - 13
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© The Author(s), 2024. Published by Cambridge University Press on behalf of Provincial Council of the English Province of the Order of Preachers.

1. Introduction

Thomas Aquinas offers five arguments for God’s existence, called the ‘Five Ways’, in his Summa theologiae Ia q.2 a.3 resp. The Fifth Way is a teleological argument ‘from the governance of things’. The argument cites final causes in nature and concludes to a being with intelligence directing the whole of nature, which is God. I will not defend the argument. My task is to bring clarity to how it works and the thinking behind the premises. This will help one’s evaluation of the argument. I first present the premises of the Fifth Way and pose some key interpretive questions (Section 2). The text offers little guidance as to the types of purposive activity the argument invokes. Thus, I discuss the kinds of purposive activity in nature Aquinas sees (Section 3) and why he thinks that things act for the ‘best’ (Section 4). The discussion then treats why he thinks nature shows purposive activity and why this needs an intelligent source (Section 5). A final section (Section 6) briefly looks at how the argument concludes to God’s existence, after its sub-conclusion that a single being directs all natural things.Footnote 1

2. Basics of the argument

The text of the Fifth Way:

The fifth way is taken from the governance (gubernatione) of things. We see that some things which lack intelligence (cognitione), namely, natural bodies, act for an end, which is evident from their acting always, or usually, in the same manner, so as to obtain what is best (optimum). Thus, it is evident that this is not by chance, but by a tendency (intentione), that they reach their end. Now whatever lacks intelligence does not tend to an end unless directed by something that has knowledge and intelligence (cognoscente et intelligente), as an arrow is directed by an archer. Therefore, there is some being with intelligence by Whom all natural things are directed toward an end; and this we call God.Footnote 2

The premises and conclusion:

  1. (1) We see some things which lack intelligence, natural bodies, act for an end.

    1. (a) These things are seen to always, or usually, act in the same way.

    2. (b) They tend to act to obtain the best result.

    3. (c) So, this shows they act that way, not by chance, but by a (directed) tendency to an end (from 1a and 1b).

  2. (2) If something lacks intelligence and tends to an end, then it is directed to do so by something with intelligence and knowledge of that end.

  3. (3) So, natural bodies lacking intelligence and acting for an end require something else directing them (implied, from 1 and 2).

  4. (4) So, there is some being, with knowledge and intelligence, directing all natural things to their end (from 3).

  5. (5) In conclusion, this being we call God (from 4).

The Fifth Way has roots in Aristotle’s Physics II c.8. There Aristotle argues for (1) final causes in nature and (2) that this goal-directed activity seeks good outcomes. (3) Further, nature often effects this in coordinated steps.Footnote 3 The Fifth Way, like each of the other Five Ways, begins with a perceived fact in nature. Some things ‘which lack intelligence’ (quae cognitione carent) clearly act for an end. Why think this? They are seen to act always or usually ‘in the same manner’ in order ‘to obtain what is best’ (optimum). This happens not by chance but due to their being guided by something else having ‘knowledge and intelligence’ (cognoscente et intelligente) of the end.Footnote 4 He concludes that this being is what we call God. The Fifth Way does not explicitly rule out an infinite regress of causes of finality but that may be implied. The first Three Ways all treat the problem of a causal regress in some fashion.Footnote 5

The compact reasoning of the Fifth Way raises a number of interpretive questions. Here I can only treat a select number of the more prominent issues. In the first premise, which natural bodies are involved? All or just some, i.e., certain types? Aquinas gives no examples from nature. If the argument is talking about all bodies, then it seems odd to say that even inanimate things like rocks and dirt act for an end. But then, we see that the closing lines mention the direction of ‘all natural things’ (omnes res naturales). It would seem inadvisable for the Fifth Way to go from particular claims about some natural bodies (premises 1–3) to a universal sub-conclusion (premise 4) and conclusion about all natural bodies. The right consistency of scope in the premises is needed. In premise 1, Aquinas says that things in nature act for an end because (1) their activity tends to be regular and (2) for the ‘best’ result. Both points need explaining. Non-teleological causes might account for regularity. It is not clear what ‘best’ involves. I do not seek the best cup of coffee or the perfect drive to work in the morning. Plants and animals seldom tend toward perfection. Further, the crucial premise (premise 2) that finality in nature needs an intelligent source is simply stated, with no warrant.

The end of the Fifth Way speaks about some being with intelligence (aliquid intelligens) directing all natural things. It is unclear how the argument gets to a single directing being, as it seems to claim. That ‘Every X is directed by some Y’ does not show ‘Some (one) Y directs every X’. Added reasoning is needed. Last, there is the quick and not obvious final step that we should call this being God. Thus, there are questions around (1) the argument’s teleological scope, the significance of things acting (2) regularly and (3) for the best, and why this is due to (4) a single being (5) that is God. In the present scope, I can only explore what may be the gist of Aquinas’s thinking on these matters.

3. Types of finality

Two interpretations of the scope of finality in the opening premise(s) are considered here. One view emphasizes certain activities of plants and animals as the model. I should first note that Aquinas thinks that beings with reason ‘act for an end’ properly speaking and principally so. Other things do so in a lesser, derivative way. He notes in Summa theologiae I-IIae q.12 a.5 resp. that:

The other way of intending an end belongs to the mover, insofar as he ordains the movement of something, either his own or another’s, to an end. This [way] belongs to reason alone. Hence, irrational animals do not intend an end in this [first] way, which is to intend properly and principally, as stated above [I-IIae q.12 a.1].Footnote 6

Even animals only act for ends in an instinctual manner. In the Commentary on Aristotle’s Physics (II l.13 n.3–5), Aquinas cites some standard Aristotelian examples of purposive activity in nature. Swallows build nests. A spider makes its web. Plants sink roots into the earth for nourishment and grow leaves to shade their fruit. Aristotle mentions how rain causes living things to flourish, in a kind of concerted natural system. Thus, one view of the Fifth Way is to see living things as the main source of examples Aquinas means, at least to get the argument going. Perhaps, these select instances are enough to show a guiding intelligence in the background of nature.

A second, ‘wide’ interpretation sees the Fifth Way (in premise 1) includes all natural bodies, even inanimate things and possibly the Democritean four elements (earth, air, fire, and water). John Wippel thinks that Aquinas has in mind, ‘Natural bodies, that is to say, [all] things which are equipped with their own natures but lack the power of cognition …’. Examples thus include ‘a heavy body tends to fall or a hot body to rise’.Footnote 7 Such a wide reading of the earlier premises squares better with the seemingly universal conclusion about ‘all natural things’.

But why would, say, rocks falling or hot air rising be acting for an end? (It is not a normal view in the present-day.) In fact, Aquinas himself thinks so. Book III of Summa contra Gentiles treats divine governance in chapters 1–163. Aquinas in chapter 2 of Book III argues that, ‘It must first be shown that in acting every agent intends an end (intendit aliquem finem)’.Footnote 8 In the Prologue in chapter 1 of Book III, Aquinas has already discussed how the divine nature directs all things to their proper end, including ‘the celestial bodies whose motions always occur in the same way’. He also notes there that the terrestrial ‘corruptible bodies’ (c.1 n.6) in their ‘proper actions’ contribute to the good of the natural order. In chapter 19 n.3 of Book III, he discusses examples of how things in their activities imitate the goodness of the divine nature. Examples include how material bodies ‘naturally desire to be’, that is, they try to keep on existing. Those bodies which are corruptible ‘naturally resist corrupting agents and tend toward a place where they may be preserved, as fire inclines upward and earth downward’. Nonliving things act and interact with each other to contribute to a natural order that sustains living things and their supporting environments.Footnote 9 In short, Aquinas believes and extensively defends the view that all natural bodies show goal-directed tendencies. The Fifth Way seems more likely about finality in this wide scope. It aligns with Aquinas’s view of nature and a needed consistency among the premises and conclusion.

4. Toward an optimum

What about things without intelligence acting for what is ‘best’ (optimum)? After arguing in Contra Gentiles chapter 2 of Book III that every agent acts for an end, Aquinas in chapter 3 of Book III follows up with the thesis that ‘every agent acts for a good’ (omne agens agit propter bonum). In short, he thinks that things act toward a good on multiple levels.

Aquinas holds that, in a basic sense, just to exist or acquire a further state of actualization is a kind of good outcome. Every activity of an agent is ordered toward being (esse), Aquinas says in Contra Gentiles III c.3, ‘either to conserve the species or individual, or to acquire some new mode [of being]’. He continues, ‘Now, the very fact of being is a good, and so all things desire to be. Therefore, every action and movement are for the sake of a good’. Things are good insofar as they are actual or obtain some new state of actuality. Goodness here does not add some distinctive new property to what is already existing. Instead, ‘good’ expresses a certain aspect or mode of considering the being that a thing already has or could acquire. In the Disputed Questions on Truth (De veritate) q.1 a.1, Aquinas explains, ‘Good expresses the correspondence of being to the appetitive power, the reason is, and so we note in [Aristotle’s] Ethics, the good is “that which all things desire”’.Footnote 10 For Aquinas, what involves being, in virtue of such, always corresponds to some degree of goodness. Thus, for a natural body to act for an end is to tend toward some actual state that is also (coextensively) a good.

In a further sense, Aquinas also thinks that natural bodies act in ways that are somehow fitting or advantageous, for themselves and often for others. Plants and animals do things to maintain themselves. Aquinas is not saying that things seek a ‘best’ in an idealized or perfect way. Later in the Summa theologiae, in Ia q.91 a.3 resp., he qualifies the idea of acting for what is best, ‘Therefore, God gave to each natural being the best disposition, not absolutely so, but according to its proper end’. This is consistent with the above notion that things act to conserve themselves or the species. In the Commentary on Aristotle’s Physics (II l.12 n.3), Aquinas notes that a thing in nature aims to be ‘better and fitting’ (mellius et commodious) as it can be under the circumstances.Footnote 11 For instance, human beings have limbs and feet for walking and running. They are not, say, the fastest animals nor do they have the best sense of smell. But human beings are equipped well enough for staying alive (for a while) and maintaining the species. In one argument in Contra Gentiles III c.3 n.9, for the conclusion that every agent acts for a good, Aquinas asserts that ‘we observe that what happens in the workings of nature is either always, or mostly, for the better (quod melius est)’. For example, plants’ leaves are arranged to protect the fruit, while in the animal world, the bodily organs are arranged and disposed to protect the animal from harm. All this suggests that the optimizing noted in the Fifth Way is mainly about things seeking relatively better circumstances. A thing will act in ways that are good for being the kind of thing it is and the situation(s) in which it is.

Finally, Aquinas later in the Summa, well after the Fifth Way, speaks about a providential order for things where their activities are oriented to the ‘good’ of things on multiple levels, in ways beyond their own individual advantage. In Summa theologiae Ia. Q.65 a.2 resp.:

Now if we wish to assign an end to any whole, and to the parts of that whole, we shall find, first, that each and every part is for the sake of its proper act, as the eye for [the act of] seeing. Secondly, that less honorable parts exist for the more honorable, as the senses for the intellect, the lungs for the heart. Thirdly, that all parts are for the perfection of the whole, as the matter for the form, since the parts are, as it were, the matter of the whole [substance]. Furthermore, the whole man is on account of an extrinsic end, that end being the enjoyment of God. Thus, in the parts of the universe every creature exists for its own proper act and perfection. And second the less noble creatures for the nobler, as those creatures beneath man exist for the sake of man. Moreover, each and every creature exists for the perfection of the entire universe. Furthermore, the entire universe, with all its singular parts, is ordained towards God as its end, inasmuch as it imitates, as it were, and represents the divine goodness, to the glory of God.

The parts of things can each have their proper function, like the eye for seeing. But parts and systems can serve other ones, like the senses serve the intellect. Next, parts serve the advantage and completion of the whole thing, such as when the organs keep the whole body alive. Aquinas thinks that things in nature can act for their own preservation and perfection. At the same time, their existence and activity support larger environments allowing for living things in general to flourish and human beings in particular. The activity of creatures also serves a larger universal plan. Ultimately, the universe, along with its ‘singular parts’ is something that ‘represents the divine goodness’. (This coordinated, providential plan is not stated in the Fifth Way but some think it is hinted.) In Contra Gentiles II c.39, Aquinas notes that ‘the good and the best’ for the universe involves ‘the mutual order of its parts’ and by this ‘the universe is constituted in its wholeness’, in which its optimal good consists.Footnote 12 An important point here is that Aquinas does not see a conflict, in principle, between individual things acting for their own good and their being governed in bringing about a larger universal plan. Things may act for the best in the individual and concerted senses, as commentators note.

This integration in Aquinas between an individual good and a universal plan also explains, Aquinas suggests, why things in nature fall apart, or even where one natural thing harms another. What is bad for one thing may be better for the whole order.Footnote 13 There are forms of beauty and rich complexity that the world would not have if there were no destruction or conflict among individuals or types. However, divine permission of this leads to questions beyond the present scope.

5. Why finality?

Why does Aquinas think there is finality in nature? Perhaps objects in the world are just configurations of matter (or atoms) guided by scientific laws. The actions of all things reflect ultimately the laws of physics brought to bear on the physical constitution of things. No need for talk of finality. In the century after Aquinas, William Ockham will hold that teleological explanations are inapplicable to the causal origins and activities of natural things which lack intelligence.Footnote 14 Early Modern thinkers would revive Ancient atomism and consciously do away with Aristotelian substantial forms and final causes.

Some thinkers hold that there are instances of purposive activity in nature. The activities of at least some (non-intelligent) things appear goal-directed. Yet, they think, it is a leap to posit some intelligent higher cause in the background. After all, Aristotle sees final causes in nature but no cosmic creator or grand mind marshalling the universal order. There is ‘design without a designer’ in a current phrase for the position. All species of living things come to be and perpetuate themselves by a thoroughly ‘blind’ and materialistic system. The metaphor of blindness suggests no intelligent direction of nature in the background.Footnote 15 For now, I will present some ideas on why Aquinas sees finality in nature and why this points to a source with intelligence.

From the writings of Aristotle, Aquinas is familiar with Ancient Greek thinkers who reject final causes in nature. Of Aristotle’s four causes – material, formal, efficient, and final – some thinkers reject final causes. Some even reduce everything to the material cause, where the material constitution of things explains all activity. To say that the material cause alone explains this, Aquinas and Aristotle think, is like saying there is just something about the wood which can arrange itself into a ship.Footnote 16 But isn’t this just to beg the issue that a final cause is needed?

For Aquinas and Aristotle, particularly in the case of plants and animals, it is obvious that the natures of agents include embedded dispositions to act for a determinate purpose. Aquinas offers a line of reasoning in Summa theologiae Ia-IIae q.1 a.2:

But an agent does not move except by intending an end (ex intentione finis). For if the agent were not determined to some particular effect, it would not do one thing rather than another. Thus, in order to produce a determinate effect, it must be determined to a certain one, which has the nature of an end. Further, just as this determination is effected in the rational nature by the ‘rational appetite’, which is called the will; so, in other [non-rational] things, it is caused by their natural inclination, which is called the ‘natural appetite’.Footnote 17

He poses here non-intelligent agents acting by a kind of ‘natural inclination’. Further on in that same article Aquinas explains why nonrational beings still can be seen as acting for an end:

Since they do not know the nature of an end as such, and consequently cannot ordain anything to an end, but [they] can be ordained to an end only by another.

A key notion here is that natural agents acting from a kind of natural necessity are, as he says here, ‘determined to some particular effect’. Similar reasoning is in Contra Gentiles II c.23 that agents are ‘determined to one effect’ (determinatur ad unum effectum). This is in contrast to a rational agent with an intellect and will considering various means to a goal. Such an agent can bring about contrary effects. Mike can decide on pizza or a healthy salad for lunch. Should he go with what tastes good or stick to his diet? Natural agents act in specific and regular ways. When an agent acts, Aquinas is saying, it has a set inclination toward a particular end. Large rocks do not spontaneously float upward. They and other bodies tend to fall (until they cannot). Oaks produce acorns, not apples or basketballs. Fish always swim but never run marathons.Footnote 18 Agents act in specific and definite ways to produce determinate, repeating effects, if the agent is unimpeded.

The reason is found, Aquinas thinks, in the agent possessing a disposition toward certain repeated operations. It has a disposition to act or move in certain ways, given how the nature of the thing is constituted. The example in the Fifth Way of an arrow shot by an archer can mislead readers, at least one commentator notes. Aquinas’s point is not that beings without intelligence act for a goal passively impressed on them from outside their nature, by some intelligent being using the object like a tool. Instead, as Aquinas explains in Ia q.5 a.2 of Summa theologiae: ‘Further, upon the form follows an inclination to the end, or to an action, or something of the kind; for everything, in so far as it is in act, acts and tends towards that which is in accordance with its form …’.Footnote 19 Tendencies are rooted in the nature of what something is and the features it has.

But Aquinas does not think that the account concludes with a kind of embedded disposition in the thing to act in a (for him) obviously goal-directed manner. Having such is not a matter of chance, a result of the random confluence of different efficient causes acting on matter. If an agent is to act in a determinate way, this happens by some act of knowledge or intention proposing a determinate end for that action.Footnote 20 What does not determine its own end is indicative of a superior agent in the background with knowledge and power to effect this dispositional tendency in natural agents which lack knowledge.

Such a consideration is strengthened for Aquinas by the notion that things which lack intelligence appear to act for certain ‘good’ outcomes, where as we saw above that the nature of the effected goodness occurs on multiple levels. He argues in the Disputed Questions on Truth (De veritate):

Material and efficient causes, as such, are only causes of the existence [of effects]. They are not sufficient (non autem sufficient) to produce goodness in them to be aptly disposed in themselves, so that they could continue to exist, and toward others to help them. Heat, for example, of its nature and can break down other things, but this breaking down is good and helpful only if it happens up to a certain point and in a certain way. Consequently, if we do not admit that there exist in nature causes other than heat and similar agents, we cannot assign any cause why things happen in a good and orderly way.Footnote 21

Things, he says, are disposed to continue to exist and try to flourish. For instance, living things have to act in regular, complex ways just to stay alive. Second, natural agents seem to ‘help’ other individual objects and do so in a way he thinks requires a kind of calibration of the activity involved, as the example of heat suggests to Aquinas. In addition, things do not act for their own individual good or occasionally for the good of other things. As Aquinas goes on to note in this responsio in De veritate, if there were only, say, material and efficient causes in nature, ‘then all the harmony and usefulness found in things would be the result of chance’. For things to go well with individuals and species, at least enough of the time, this takes a unified order in nature he sees indicative of intelligent coordination and guidance. It will not do just to describe a thing’s structure and chemical composition to account for, for instance, the function of leaves on trees, legs on animals, or plants sprouting from seeds. Ecological systems are commonly described using profoundly teleological language.Footnote 22

Aquinas is thus proposing that things in the world have every appearance of acting for an end because they are. Second, explaining this cannot just be in terms of chance configurations of matter by many random collisions of different lines of efficient causation over time. The structures and functions of individual objects are too complex. The myriad ways things seem to come together in a kind of sophisticated, opportune ordering of mutual aid and preservation, he thinks, looks too obvious to him not to have been intentionally coordinated by something with the requisite power and intelligence guiding the entire system. Such a state of affairs in the world, Aquinas poses in the Fifth Way (premise 2), cannot be the result of mere chance. The chance event, Aquinas says, sees the convergence of two or more causal lines where none of the agents intends the convergence and the unexpected outcome.

To sum up, Aquinas thinks that natural agents act to produce (1) determinate effects, (2) tending toward good outcomes, on various levels of nature, and in a way (3) suggesting a kind of coordinated, unified natural order. Activity for an end is evident throughout nature. To him it looks too well coordinated on various levels not to indicate a kind of supra-human intelligence behind all of it. Only something intelligent can foresee the sequences of causal means and ends leading to outcomes involving so many objects in a complex, coherent natural system. Aquinas argues in Contra Gentiles II c.24 n.4 that such an order is obviously the work of a higher cause with intelligence:

For things can be ordered only by knowing (per cognitionem) their relation and proportion to each other, and to something higher, which is their end. For, the order of certain things to each other is for the sake of their order to an end. But only a being endowed with intellect is capable of knowing the mutual relations and proportions of things is only within the capability of something with intellect. And to judge certain things by the highest cause pertains to wisdom.

From this, Aquinas will conclude further on in that chapter (II c.24) that, ‘God brought things into being by ordering them’. The end-state toward which things are constituted to aim at must somehow pre-exist in the rational mind of some being. I have tried, then, to convey how Aquinas sees several converging points of evidence for his view that nature shows a concerted ordering of final causes directed by a superior intelligence. Assessing how this outlook stands up to criticism would be a separate project. For now, it gives us a sense of the main reasoning behind the Fifth Way.

6. End of the Fifth Way

The last premise of the Fifth Way (premise 4) claims that there is some being with intelligence (aliquid intelligens) directing the purposive activities of ‘all natural things’. Human beings, who tend to act with intentionality, might seem exempt. But there is much purposive activity in humans and animals showing little or no awareness of the end.Footnote 23 For instance, our organs and biological systems function beneath the threshold of our conscious control (or much so). So, ‘all natural things’ may include us. Aquinas then concludes this agent is what ‘we call God’. Even commentators who normally give Aquinas’s positions a sympathetic hearing hold varying views on how persuasive the Fifth Way ultimately is.Footnote 24 What might Aquinas’s thinking be behind these final steps? Room permits only brief thoughts.

The wording of the last premise suggests that a single being in the background of nature guides things. But no justification is offered, from what I see. Lubor Velecky thinks that the Fifth way quite apparently argues that, ‘The complex phenomena of entities without knowledge for themselves, their kind, and the universe is explained by [a single] intelligence commensurate with the job at hand’.Footnote 25 The teleological argument for God in Contra Gentiles I c.13 n.35 seems more explicitly to argue for a single source governing nature. Aquinas’ basic reasoning for this in Contra Gentiles I c.13 is that: ‘Contrary and discordant things cannot come together in one order, always or for the most part, except under someone’s governance’. As previously noted, Aquinas in various places thinks that nature would not appear as a unified system of well-coordinated ends in the absence of a single maker and governor. Where there is one universal order, there is one cause governing the whole thing.Footnote 26 Perhaps Aquinas could assume his original audience for the Five Ways already knew this type of reasoning. So, he does not invoke it. For what it is worth, Aquinas makes use of this sort of argument in the third of three arguments for God’s oneness in Ia q.11 a.3 resp. In this argument, that God is one is apparent from ‘the unity of the world’, since ‘things that are diverse do not harmonize into a single order, unless they are ordered to do so by one thing’.

I now turn to the laconic conclusion, that this being is what ‘we call God’. To understand the ending of the Fifth Way, it helps to say something about how Aquinas ends each of his Ways. The conclusion of each of the Five Ways uses a kind of nominal description to ‘pick out’ something that has the divine nature: an immovable first mover, a first uncaused efficient (agent) cause, an uncaused necessary being, a supreme being, and, now in the Fifth Way, an ultimate intelligent source of purposive activity in natural things. The key here is that such a description be able exclusively to designate the divine nature from a knowledge of its causal effects seen in this world.Footnote 27 Aquinas thinks that a reflective believer in classical monotheism would recognize such characterizations as true only of what has the divine nature. Aquinas in Ia q.13 a.8 ad 2, says: ‘And in this way the name “God” signifies the divine nature. For, for this name was imposed to signify something existing above all things, that which is principle of all things, and removed from all things; for this is what those who name God intend to signify’. F.C. Copleston sums up what is happening here:

And it is true to say that ‘all men’ call this being ‘God’, in the sense that all who acknowledge the existence of a transcendent, supreme, and uncaused cause do in fact recognize this being as divine. At the same time Aquinas is well aware that the notion of a first cause or immovable mover or of a necessary being is not, taken by itself, all that is generally meant by the word ‘God’. And he proceeds in the following sections of the Summa theologica to argue that this being must possess certain attributes.Footnote 28

Only after the Five Ways in Summa theologiae Ia q.2 a.3 does Aquinas go on to treat in Ia qq.3–11 the well-known, core attributes of God’s nature – divine simplicity, immateriality, perfection, goodness, infinity, omnipresence, immutability, eternity, and oneness. The attributes which have to do with God’s will and intellect follow in Ia qq.14–26 (which include God’s knowledge, will, power, life, love, and providence). The Fifth Way at the end at least points to a single source of finality in nature. But Aquinas, in any case, does not try to establish God’s oneness in a serious way until Ia q.11.

References

1 In a book on the Five Ways under contract with Cambridge University Press, Reading Aquinas’s Five Ways, I will offer a longer treatment of the Fifth Way. My thoughts are abridged here to fit this article.

2 Quinta via sumitur ex gubernatione rerum. Videmus enim quod aliqua quae cognitione carent, scilicet corpora naturalia, operantur propter finem, quod apparet ex hoc quod semper aut frequentius eodem modo operantur, ut consequantur id quod est optimum; unde patet quod non a casu, sed ex intentione perveniunt ad finem. Ea autem quae non habent cognitionem, non tendunt in finem nisi directa ab aliquo cognoscente et intelligente, sicut sagitta a sagittante. Ergo est aliquid intelligens, a quo omnes res naturales ordinantur ad finem, et hoc dicimus Deum.

Summa theologiae Ia q.2 a.3 resp., in Sancti Thomae Aquinatis Opera omnia iussu Leonis XIII, ed. by the Leonine Commission, vols. 4–12 of 50 vols. (in preparation) (Rome: 1882–). Translated from the Latin by The Fathers of the English Dominican Province as Summa Theologica (New York: Benzinger Bros., 1947). I have also consulted Alfred Freddoso’s translation of the Summa in progress on his personal website at https://www3.nd.edu/~alfreddos/. I generally follow a cited English translation of a work by Aquinas but include frequent changes of my own. I mostly use the Latin editions of Aquinas’s works available in the Corpus Thomisticum online at www.corpusthomisticum.org.

3 The roots of the Fifth Way in Physics II c.8 and these points made by Aristotle are noted by Michael Augros in his Aquinas on Theology and God’s Existence: The First Two Questions of the Summa Theologiae Newly Translated and Carefully Explained (Heusenstamm, Germany: Editiones Scholasticae, 2019), p. 411.

4 Here I follow Laurence Shapcote (1864–1947) in his translation of the Summa theologiae credited to the English Dominican Fathers, where he uses ‘intelligence’ for the first two instances of cognitio in the Fifth Way and ‘knowledge and intelligence’ (cognoscent et intelligente) near the end. John Owens notes that this underscores that the being in question has something like an intellect with understanding able to grasp essences and ends. Aquinas thinks that nonrational animals, such as a chimpanzee, have a kind of basic awareness. But this obviously does not fit the type of superior intellect needed for the conclusion. John Owens, ‘Aquinas’ Fifth Way’, New Blackfriars, 101 (2020), 726–39, see pp. 727–28. My focus in this article on the teleological scope of the Fifth Way is partly indebted to Owens.

5 Aquinas in Summa contra Gentiles III c.2 wants to establish the thesis that ‘in acting, every agent intends an end’. There he gives multiple arguments that there cannot be an infinite regress of final causes. He offers four such arguments in his Commentary on Aristotle’s Metaphysics II l.4 n.1–3.

6 See also Summa theologiae I-IIae q.1 a.2 resp., I-IIae q.6 a.1 resp.

7 See for instance, John Wippel, The Metaphysical Thought of Thomas Aquinas (Washington, DC: Catholic University of America Press, 2000), p. 480. Thomas Gilby sees the teleological observation opening the Fifth Way extending ‘to all creatures … all things that do not of themselves possess their ends’. In ‘The Fifth Way’, p. 207, which forms Appendix 5 to volume 2 (pp. 206–08) of the Blackfriars edition of the Summa Theologiae, ed. by Thomas Gilby et al., 61 vols. (London: Eyre and Spottiswoode; New York: McGraw-Hill Book Company, 1964–1981).

8 Contra Gentiles III c.2, in Sancti Thomae Aquinatis Opera omnia iussu Leonis XIII, ed. by the Leonine Commission, vols. 13–15 of 50 vols. (in preparation) (Rome: 1882–). Trans. by Anton Pegis, James Anderson, Vernon Bourke, and Charles O’Neil as On the Truth of the Catholic Faith, 5 vols (New York: Doubleday, 1955–57), reprinted as Summa Contra Gentiles (Notre Dame: University of Notre Dame Press, 1975). I have made changes to the translation where it is used.

Relevant discussions of this principle, often phrased as ‘every agent acts for an end’, occur in Contra Gentiles III c.1–3, 16–20 and in Summa theologiae Ia-IIae q.1 a.2. A classic treatment is George Klubertanz’s, ‘St. Thomas’ Treatment of the Axiom, Omne Agens Propter Finem’, in An Etienne Gilson Tribute, ed. by C.J. O’Neil (Milwaukee: Marquette University Press, 1959), pp. 101–17.

9 A point developed by Michael Augros, Aquinas on Theology, p. 423.

10 Quaestiones disputatae De veritate q.1 a.1 resp, in Sancti Thomae de Aquino Opera omnia iussu Leonis XIII, ed. by Leonine Commission, Vols. 22(1/1)–22(3/2) of 50 vols, (Rome: 1882–). Trans. by Robert Mulligan, James McGlynn, and R. Schmidt as On Truth, 3 vols (Chicago: Henry Regnery, 1952–1954). I have made changes to the translation where it is used.

11 The larger context is worth quoting: ‘That which most strongly demonstrates that nature acts for the sake of something is the fact that in the operation of nature a thing is always found to be as better and fitting as it can be. Thus, [for example] the foot is made in a certain way to be suitable for walking’. In octo libros Physicorum Aristotelis expositio II l.12 n.3, ed. by P. Maggiolo (Turin: Marietti, 1954). Translated as Commentary on Aristotle’s Physics, trans. by Richard J. Blackwell, Richard J. Spath, W. Edmund Thirlkel (New Haven: Yale University, 1963). I have made changes to this translation. Michael Augros, Aquinas on Theology, pp. 440–44, explains Aquinas on the optimal good in a way helpful to the present discussion.

12 Aquinas is arguing in Contra Gentiles II c.39 n.7 that the fact the world is made up of individual substances, distinct from each other, cannot be by chance. ‘But the good and the best in the universe consists in the mutual order of its parts, which cannot be without their distinction from one another; for by this order the universe is constituted in its wholeness, and in this is its optimal good. Therefore, it is this very order of the parts of the universe and of their distinction which is the end of the production of the universe. It remains that the distinction among things is not [just] by chance’.

13 Summa theologiae Ia q.19 a.9 resp., q.49 a.2. In Ia q.22 a.2 ad 2 Aquinas says: ‘Hence, corruption and defects in natural things are said to be contrary to a particular nature. Yet, they are in keeping with the universal plan [of nature], insofar the defect in one thing yields to the good of another, or even that of the whole universe. The reason is the corruption of one is the generation of another, through which a species is conserved in existence. Therefore, since God is the universal provider of all being, it belongs to His providence to permit certain defects in particular things, so that the perfect good of the universe may not be impeded. For if all evil were prevented, much good would be absent from the universe. A lion would not live if there were no slaying of animals; nor would the patience of martyrs exist if there were no tyrannical persecution’.

14 William Ockham, Quaestiones quodlibetales IV q.1–2, in what is thought to be his latest treatment of final causality. Translated as Quodlibetal Questions: Quodlibets 1–7, by Alfred Freddoso and Francis Kelly (New Haven: Yale University Press, 1998). In Quod IV q.1 (p.259) Ockham finds that final causation ‘is inappropriate in the case of natural actions’ and is so ‘only in the case of voluntary ones’.

15 Michael Augros discusses the the notion of “blind necessity” in Aquinas on Theology, p. 428. See Benignus Gerrity, Nature, Knowledge, and God (Milwaukee: Bruce Publishing, 1947), pp. 87–88. See also Edward Feser, Scholastic Metaphysics: A Contemporary Introduction (Heusenstamm, Germany: Editiones Scholasticae, 2014), pp. 96–97.

16 Commentary on Aristotle’s Physics II l.14 n.8.

17 Ia-IIae q.1 a.2 resp. See also Aquinas’s Commentary on the Sentences of Peter Lombard II d.25 q.1 a.1.

18 The examples are adapted from a source or blend of sources I cannot readily retrace. The second is possibly from Christopher Martin’s God and Explanations, p. 182., and also Edward Feser, Scholastic Metaphysics, p. 88.

19 In the Commentary on the Sentences, Aquinas says that the actions of natural bodies are ordered to their actions in virtue of being ‘constituted’ to have a nature which acts for an end, in Sentences II d.25 q.1 a.1 solutio. Aquinas goes on to argue that the whole of nature shows itself to be the work of something with intelligence.

20 Sentences II d.25 q.1 a.1 solutio: ‘For the determination of an agent to some particular action, it has to be through some act of knowing presented as an end of that action’. In Scriptum super libros Sententiarum Magistri Petri Lombardi II d.34 q.1 a.1, vol.2 of 4 vols, ed. by R. Mandonnet (vols.1–2) and M. Moos (vols.3–4) (Paris: Lethielleux, 1929–1947). Currently, there is no published English translation of the whole work.

21 De veritate q.5 a.2 resp., in an article on ‘Whether the world is ruled by providence’ (utrum mundus providentia regatur). Michael Augros summarizes this type of argument from the good outcomes of natural agents, ‘Many natural actions, such as those of living things, regularly produce many good and functional outcomes (such as useful organs), and any one functional outcome is just a single possibility in an infinite ocean of dysfunctional alternatives. It is therefore impossible that nature not be oriented toward the good’. Aquinas on Theology, p. 438.

22 Examples are borrowed from Christopher Martin, Thomas Aquinas: God and Explanations (Edinburgh: Edinburgh University Press, 1997), pp.184–185. Also helpful is Benignus Gerrity, Nature, Knowledge, and God, pp. 87–99.

23 Michael Augros, Aquinas on Theology, p. 423.

24 Christopher Martin, God and Explanations, pp.182–183, finds the reasoning more ‘strong’ than ‘conclusive’ in the final steps, after initially entertaining doubts about the effectiveness of the Fifth Way. John Wippel is brief and noncommittal on whether the Fifth Way succeeds, Metaphysical Thought, p.485. Dennis Bonnette, who has written extensively on the Five Ways, endorses the reasoning of the Fifth Way in a recent, brief piece posted on his website, ‘Understanding the Mysterious Fifth Way to God’s Existence’ at www.drbonnette.com. Lubor Velecky finds this last part of the argument makes a plausible case for God, Aquinas’ Five Arguments in the Summa Theologiae 1a 2, 3 (The Netherlands: Pharos, 1994), p. 97.

25 Lubor Velecky, Aquinas’ Five Arguments, p. 94.

26 Summa theologiae I-IIae q.1 a.2 ad 3. In Contra Gentiles III c.64 n.6 there is a succinct argument for a single orderer of nature: ‘Furthermore, things that are different in their natures do not come together into one order unless they are gathered by a single orderer into one unit. But in the whole of what there is, things are distinct and possessed of contrary natures; yet, all come together in one order. Moreover, while some things make use of the actions of others, some are also helped or commanded by others. Therefore, there must be one orderer and governor of the whole of things’.

27 ‘For Aquinas, any name that exclusively designates the divine nature from effects will satisfactorily serve in answering the question whether God exists. All other properties beyond that name or names belong equally to the question what God is’. David Twetten, ‘Clearing a “Way” for Aquinas: How the Proof from Motion Concludes to God’, Proceedings of the American Catholic Philosophical Association, 70 (1996), pp. 259–78, p. 271.

Summa theologiae Ia q.2 a.2 on ‘Whether it can be demonstrated that God exists’ explains this further: ‘When the existence of a cause is demonstrated from an effect, it is necessary that this effect takes the place of the definition of the cause, in proving the cause’s existence, and this is especially so in regard to God. The reason is that, in order to prove the existence of anything, it is necessary to accept as a middle term that which the word signifies, and not what it is [i.e. its essence] (quid significet nomen non autem quod quid est), for the question of its essence follows on the question of its existence. Now the names given to God are derived from His effects, as previously shown; consequently, in demonstrating the existence of God from his effects, we may take for the middle term that which the word “God” signifies. God can be shown to exist by looking at the significance of the term “God”’.

28 F.C. Copleston, Aquinas (New York: Penguin Books, 1955), p. 130.