A Thomistic Argument from Desire: Part I

A few months ago, I posted an Augustinian Argument from Desire, which attempted to use material from the writings of St. Augustine in order to address what I felt to be the principle problems for any “argument from desire” for the existence of God. The Augustinian version is interesting and, I think, deserves to be fleshed out more fully; but in this post I am beginning a new project: a Thomistic Argument from Desire. This is primarily going to be an endeavor of research, not defense. In other words, I am going to be delving into material from St. Thomas which I am inclined to think can plausibly be constructed into a successful argument, but which I have not as of yet completely mapped out. I have a general idea of what I think the flow and structure of the argument will perhaps look like, but that is certainly liable to change. Furthermore, my presentation of the argument will largely take the form of exposition. For the most part, I think the argument is pretty much already there, at least materially and implicitly, in the writings of St. Thomas, and my task will be concerned with drawing it out.

As will become evident, there are some strong correlations between this argument and Aquinas’ Fifth Way, or Argument from Design. The latter is directed towards non-rational beings such as stones, trees, planets, etc., while the former deals specifically with human beings as rational agents.

The initial inspiration for the argument actually comes from a passage in which Aquinas appears to deny the very possibility of such an argument:

“To know that God exists in a general and confused way is implanted in us by nature, inasmuch as God is man’s beatitude. For man naturally desires happiness, and what is naturally desired by man must be naturally known to him. This, however, is not to know absolutely that God exists; just as to know that someone is approaching is not the same as to know that Peter is approaching, even though it is Peter who is approaching; for many there are who imagine that man’s perfect good which is happiness, consists in riches, and others in pleasures, and others in something else” (Summa Theologica I, Q. 1, Art. 1) [1].

In the first part of the passage, we see the outline of a potential argument: 1) Man naturally desires happiness; 2) What is naturally desired by man must be naturally known to him; 3) God is man’s happiness; 4) Therefore God must be naturally known to man, i.e. it must be evident to man that God exists. But then Aquinas turns and seems to reject the argument, for he states that even though God is man’s happiness, and even though man actually does and knows that he does desire happiness, still many people don’t know what exactly their true happiness consist of, since some think it is riches, others pleasure, etc. In other words, Aquinas seems to be suggesting that an argument from desire fails because man does not know that it is actually God that he desires: so we cannot come to a knowledge of God from our innate desires alone.

But this, I believe, would be a misinterpretation. In the article which contains this passage, Aquinas is discussing “whether the existence of God is self-evident.” In particular, he is responding to (and rejecting) St. Anselm’s earlier ontological argument. So in the quoted passage, Aquinas is denying that we can have a direct, self-evident knowledge of God based on innate desires in themselves, a priori. He is not, however, denying that in principle one could argue a posteriori from those innate desires to the existence of God. This argument attempts to do the latter. It is not suggesting that all people have an immediate, self-evident knowledge of God’s existence; but rather that all people have innate, natural desires from which we can argue to God’s existence.

Of course the task is already daunting, since people today just don’t think in terms of having a “perfect good”. So the argument must start from a more modest point: all people have desires for certain ends for the sake of which they act. This is rooted in Aquinas’ teleological understanding of nature, in which all agent causes whatsoever, not just rational ones, act for the sake of ends; but human agents specifically are unique in that we are conscious of the ends we seek and can more or less choose between certain ends when we act (for a defense of Aquinas’ understanding of final causality, see my post here). So Aquinas writes that “in acting every agent intends an end” (Summa Contra Gentiles Book III, Chapter 2.1) [2] and later qualifies this in relation to rational agents:

“Furthermore, for every agent the principle of its action is either its nature or its intellect. Now, there is no question that intellectual agents act for the sake of an end, because they think ahead of time in their intellects of the things which they achieve through action; and their action stems from such preconception. This is what it means for intellect to be the principle of action” (SCG III, 2.6) [3].

The actions of all agents are directed towards some “definite end” and that definite end is a good: “Every action and motion are for the sake of a good” (III, 3.3) [4]. Desires/appetites are directed towards ends and those ends are goods, the fulfillment of the desires/appetites. An “ultimate” end is one which fulfills completely and absolutely the desires or series of desires; it is an “end” most properly because it is the terminus of desire: “The ultimate end is that beyond which the agent seeks nothing else” (III, 2.3) [5]. Aquinas argues that all agents can have some ultimate end, writing: “Now, in the action of all agents, one may find something beyond which the agent seeks nothing further. Otherwise, actions would tend to infinity, which is impossible” [6]. But this is likely to seem dubious to many readers, and we’ll wait to give it a fuller treatment in due course. For now, we’re just concerned with exploring the fact that humans specifically have desires directed towards ends for the sake of which they act. Not only this, but every action undertaken by a person is for an end: “It belongs to man to do everything for an end” (ST I-II, Q. 1, Art. 1) [7]. Aquinas explains:

“Of actions done by man those alone are properly called ‘human,’ which are proper to man as man. Now man differs from irrational animals in this, that he is master of his actions. Wherefore those actions alone are properly called human, of which man is master. Now man is master of his actions through his reason and will; whence, too, the free-will is defined as ‘the faculty and will of reason.’ Therefore those actions are properly called human which proceed from a deliberate will . . . Now it is clear that whatever actions proceed from a power, are caused by that power in accordance with the nature of its object. But the object of the will is the end and the good. Therefore all human actions must be for an end” [8].

In other words, when we will or desire something, it is necessarily directed towards some object as its good. It is 1) impossible to have a will/desire that is not for some object just as it is impossible to see without seeing something, and 2) impossible to will/desire some object that is not considered to be in some sense good for the agent (otherwise, it just wouldn’t be desired. For Aquinas, the good by definition is that which is desired). So a desire by definition has an object, or an end. When we act deliberatively, i.e. when we freely choose to undertake an action or course of actions, our action proceeds from our will, and our will has some end in mind. For example, when you brush your teeth, you are aiming at the end of maintaining clean and healthy teeth. When you eat food, you aim at the end of satisfying hunger. Etc. Aquinas gives a fuller account of this:

“Every agent, of necessity, acts for an end. For if, in a number of causes ordained to one another, the first be removed, the others must, of necessity, be removed also. Now the first of all causes is the final cause. The reason of which is that matter does not receive form, save in so far as it is moved by an agent; for nothing reduces itself from potentiality to act. But an agent does not move except out of intention for an end. For if the agent were not determinate to some particular effect, it would not do one thing rather than another: consequently in order that it produce a determinate effect, it must, of necessity, be determined to some certain one, which has the nature of an end. And just as this determination is effected, in the rational nature, by the ‘rational appetite,’ which is called the will; so, in other things, it is caused by their natural inclination, which is called the ‘natural appetite.’ Nevertheless it must be observed that a thing tends to an end, by its action or movement, in two ways: first, as a thing, moving itself to the end, as man; secondly, as a thing moved by another to the end, as an arrow tends to a determinate end through being moved by the archer who directs his action to the end. Therefore those things that are possessed of reason, move themselves to an end; because they have dominion over their actions through their free-will, which is the ‘faculty of will and reason.’ But those things that lack reason tend to an end, by natural inclination, as being moved by another and not by themselves; since they do not know the nature of an end as such, and consequently cannot ordain anything to an end, but can be ordained to an end only by another. For the entire irrational nature is in comparison to God as an instrument to the principal agent, as stated above. Consequently it is proper to the rational nature to tend to an end, as directing and leading itself to the end: whereas it is proper to the irrational nature to tend to an end, as directed or led by another, whether it apprehend the end, as do irrational animals, or do not apprehend it, as is the case of those things which are altogether void of knowledge” (ST I-II, Q. 1, Art. 2) [9].

Both rational and non-rational agents seek ends, but non-rational agents have no knowledge or deliberative will towards those ends; they are directed to them externally (as the Fifth Way shows). Rational agents, on the other hands, have their ends in mind when they act, and choose to pursue those ends. Thus they move/direct themselves towards those ends.

But this raises a question. For the most part, it’s probably pretty uncontroversial that when we deliberately act we act for the sake of ends, that our desires have objects, etc. The end of an action explains that action — the fact that I want healthy, clean teeth explains why I am brushing my teeth. But that end in itself does not fully explain the action. As Aristotle writes at the beginning of his Nicomachean Ethics, the end of a certain action is either sought for its own sake, or for the sake of some further end:

“Suppose, then, that the things achievable by action have some end that we wish for because of itself, and because of which we wish for the other things, and that we do not choose everything because of something else — for if we do, it will go on without limit, so that desire will prove to be empty and futile. Clearly, this end will be the good, that is to say, the best good” (NE 1.2, 1094a18-23) [10].

Consider, again, brushing your teeth. You undertake the action of brushing your teeth because you know that you want clean and healthy teeth and that brushing them is a necessary means to achieving that desire. But why, exactly, do you want clean and healthy teeth? There might be a myriad of reasons, but chief among them is probably something such as wanting to preserve the teeth throughout one’s life so as to keep their important function. But why would one want to preserve the teeth so as to keep their function? Because they are so beneficial in the significant processes of eating, speaking, etc. But why would we want to be able to effectively eat and speak? And so on, and so on. These further “whys” are perhaps not consciously at the forefront of one’s mind as one brushes one’s teeth, but they are nonetheless the real underlying reasons or ends for the action. Maintaining clean and healthy teeth is an end of brushing the teeth, but is not an end in itself, an ultimate end; no one would brush their teeth just for its own sake if it weren’t necessary, or if they did, it would be because of some additional pleasure derived therefrom. Every action directed towards an end is either for its own sake, or for the sake of some further end; the vast majority of all our actions fall into the latter category. But is there some actions which are legitimately undertaken for their own sake? Is there really a “best good” as Aristotle termed it, which is sought for no other reason than itself? If so, is there just one such best good?

Aquinas answers these questions affirmatively. He writes that “it is contrary to the nature of an end to proceed indefinitely. Therefore it is necessary to fix one last end” (ST I-II, Q. 1, Art. 4) [11]. Why so?

“Absolutely speaking, it is not possible to proceed indefinitely in the matter of ends, from any point of view. For in whatsoever things there is an essential order of one to another, if the first be removed, those that are ordained to the first, must of necessity be removed also. Wherefore the Philosopher proves (Phys. viii, 5) that we cannot proceed to infinitude in causes of movement, because then there would be no first mover, without which neither can the others move, since they move only through being moved by the first mover. Now there is to be observed a twofold order in ends—the order of intention and the order of execution: and in either of these orders there must be something first. For that which is first in the order of intention, is the principle, as it were, moving the appetite; consequently, if you remove this principle, there will be nothing to move the appetite. On the other hand, the principle in execution is that wherein operation has its beginning; and if this principle be taken away, no one will begin to work. Now the principle in the intention is the last end; while the principle in execution is the first of the things which are ordained to the end. Consequently, on neither side is it possible to go to infinity since if there were no last end, nothing would be desired, nor would any action have its term, nor would the intention of the agent be at rest; while if there is no first thing among those that are ordained to the end, none would begin to work at anything, and counsel would have no term, but would continue indefinitely” [12].

So in our teeth brushing example, imagine that suddenly, for some reason, you stopped desiring to keep clean and healthy teeth. There would now be no reason to brush them. A desire is only explicable in relation to its object/end. Where the end is removed, so is the desire. But as we’ve seen, desires exist in ordered series, where ends are directed towards further ends. A particular desire in an ordered series might have an end, but if the further ends in that series have no end themselves, then that particular desire becomes futile/empty, as Aristotle put it. Suppose we have this ordered series: you desire to go to the park because you want to run; you want to run because you want to get in shape; you want to get in shape because you want to be healthy; you want to be healthy because you want to live a long life (and suppose wanting to live a long life is the only reason for desiring to be healthy). But now suppose that you suddenly stop desiring to live a long life, then there is no reason to be healthy. And if there’s no reason to be healthy, there’s no reason to get in shape. And hence there’s no reason to go on a run, and finally no reason to go the park. If the ultimate cause in the series is removed, the first desire itself is frustrated.

What this means is that if all of our desired ends are for the sake of some further end, and no desired end whatsoever is for its own sake, then the ordered series of our desires would be entirely empty. There must be some ultimate, final end to all our desires, which underlies all our desires and points/directs them to itself, which we desire for its own sake and for the sake of nothing else.

What is this ultimate/best good? Aristotle, Augustine, and Aquinas all thought it was happiness.



[1]. Aquinas, Thomas. Summa Theologica. 1265-1274. Trans. Fathers of the English Dominican Province. Coyote Canyon Press, 2010. ebook.

[2]. Aquinas, Thomas. Summa Contra Gentiles. Translated as On the Truth of the Catholic Faith by Anton C. Pegis, James F. Anderson, Vernon J. Bourke, and Charles J. O’Neil. New York: Hanover House, 1955-57. Edited, with English, especially Scriptural references, updated by Joseph Kenny, O.P. Accessed online at <http://dhspriory.org/thomas/ContraGentiles.htm&gt;.

[3]. Ibid.

[4]. Ibid.

[5]. Ibid.

[6]. Ibid.

[7]. Aquinas. Summa Theologica.

[8]. Ibid.

[9]. Ibid.

[10]. Aristotle. Nicomachean Ethics. Translated by Terence Irwin. 2nd edition. Indianapolis: Hackett Publishing Company, 1999.

[11]. Aquinas. Summa Theologica.

[12]. Ibid.

Header Image: Philipp Veit [Public domain or Public domain], via Wikimedia Commons




6 thoughts on “A Thomistic Argument from Desire: Part I

  1. How is desire an argument for anything other than a desire? We want to not die, and lots of animals would second that motion. And we want to be happy, and I’m sure there’s elephants, dolphins and apes that would second that motion as well.

    Many people do not want to die, but instead wish very much to remain a personal being with memories intact from this life, and able to build on them and experience further joy and happiness, but aren’t such desires/hopes based on things we experience in the natural world? How do we know happiness/joy except by analogy with experiences of happiness/joy in this life?

    Certainly Christians want to be happy in the “arms of God” if you will. But not everyone loves the apocalyptic Jesus of the Gospels (see Prof. Hector Avalos’s book, The Bad Jesus), and/or a personal God like Christians do.

    Others may feel more at home in an unspoken mystical embrace of life in general, or they feel more attraction to figures other than Jesus. One Reformed Christian philosopher converted to a form of Krishna-love religion. I also read about a Catholic priest in India who couldn’t help but think of God’s love in the form of Krishna even though he’d been a priest for decades. And there was another Catholic priest who ran a Christian-Hindu ashram, who converted to Christianity around the time as C. S. Lewis and who was the latter’s lifelong friend, Dom Bede Griffiths, and Griffiths books invite people to embrace a more universalistic spirituality and theological understanding, and claim that is where joy/happiness lies.

    Still others may have ecstatic joyful experiences loving Amida Buddha (see The Inner Eye of Love by William Johnson, a Jesuit who dialogued with Amida Buddhists). Or see religion prof. Conrad Hyers’s book, Once Born Twice Born Zen in which he mentions a sect of Zen Buddhism in which ecstatic love and joy is experienced in very similar terms to the “born again” experience of Protestant Christians (including imagining one is headed for hell, and then being “saved” by a revelation of love).

    Still others may discover joy and love in sects of various sorts (even small cults) rather than major religious faiths. What do such desires prove? Damn if I know. But it’s not exactly an argument or proof of anything.


    • This article is merely the first part in my unfolding argument. As such, this post does not contain the complete argument, and does not even try to move yet from general desire for happiness to the existence of God (that will come). Basically, the argument will contend that humans have a natural desire for happiness that is only fulfillable by God. It makes no appeal to any specific religion or even religion broadly, so your examples of many different religious experiences really has no bearing on the argument.


      • Philosophers can contend all they like. But questions concerning what type of God, divine force, demi-urge, exists, and what kind of afterlife exists that one is “desiring,” remains, along with the question of exactly what kind of “desire” one is talking about. Calling it “happiness.joy” is vague.


      • Sure, and Aquinas will certainly answer both what he means by God and what he means by happiness. Again, this post is literally just the first step in the argument (you have yet to respond to anything actually in this post). But even when he explains what he means by God and happiness, the argument will not appeal at any point to any specific religious experiences, and it doesn’t need to; that’s not its aim at all.


  2. How can one determine with confidence that the “argument from desire” is not based to some extent, perhaps to a large extent, on an appeal to self interest? Neither is it a proof of a particular type of god, divine force or demi-urge, nor proof of the existence of any particular afterlife.

    We agree that human beings–as well as the vast majority of living organisms–do not desire their own deaths (according of course to each of
    their limited levels and abilities to desire things). Instead the desire is to continue living, and living with less fear, sorrow, angst, pain, and more happiness, joy, pleasure (both intellectual and physical).

    But as human beings we hardly envision exactly the same afterlife. The early Hebrew view made perfect sense to the early Hebrews, namely that literally everyone but Enoch and Elijah went to the same afterlife destination, “Sheol.” But compare that with intertestamental works (Daniel), NT canonical works, Christian pseudepigraphia and apocrypha; and everything from Origen to Dante to George Macdonald.

    Compare differing ideas of the afterlife held by Christians with differing theological views (the Christian Gnostic heaven for instance).

    Compare afterlives envisioned by members of non-Christian religions, from Islamic heavenly desires to Hindu reincarnation, and Buddhist satori.

    Also if one were to measure the reality of a particular idea of “what happens after we die” by the criteria of whichever one seemed less influenced by an appeal to self interest and personal wish fulfillment, then the atheist vision of the afterlife wins hands down, since practically nobody has a personal wish to go back to being dissolved elements after they die.

    Reincarnation comes in second since you lose your memories of your previous life, and have to undergo potty training and zits all over again. But your “essential soul essence” is retained, whatever that is.

    As for other cases of desires, I don’t desire spending eternity living next to Pat Robertson; nor do I suspect that the Robertsons, Falwells, Luthers, Calvins, Catholic Popes, Orthodox Patriarchs and saints, all desire the thought of living together in the same heavenly split-level mansion for all eternity.

    Reminds me of the old joke about St. Peter giving tours of heaven to new comers and being asked about a particular cloud they passed that had lots
    of people on it with paper bags covering their heads. St. Peter tells the members says, “Be very quiet as we pass this cloud. Those are the conservative Christians, they think they’re the only ones up here.”


    • I don’t think one needs to determine that it’s not based on self-interest. Depending on what exactly you mean by self-interest, I’d say that the argument is absolutely based on it, insofar as all our desires seek our own good to some extent. The argument will be a proof (if successful) of a particular type of God, but that comes later. It will not be a proof of any particular after life or religious tradition, because it’s not meant to be. Again, all these examples in differences of religious understandings of afterlife are just entirely irrelevant to the argument itself.


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