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The Challenge of Ontological Disproofs


Dr. Peter Kreeft once noted that, “When Saint Thomas Aquinas wrote his great Summa Theologica, he could find only two objections to the existence of God, even though he tried to list at least three objections to every one of the thousands of theses he tried to prove in that great work” (Fundamentals of the Faith, p. 54). The two objections that Aquinas had in mind were the problem of evil and the apparent ability of science to explain everything without God. During my doctoral studies, however, I came across a series of articles devoted to disproving the existence of God by showing that the very attributes of divinity are incoherent and thus impossible to actualize in reality. These are known as “ontological disproofs.”

Ontological disproofs are logical arguments against of the existence of a thing based on what it would be if it existed. These arguments are very important because they do not simply purport to prove that God does not exist (like, say, the Easter Bunny or martians), but that God cannot exist (like a square circle or a married bachelor). This fairly recent form of argumentation has gained quite a bit of popularity among philosophical atheists (for example, Michael Martin devoted 23 out of 33 articles in his book The Impossibility of God to ontological disproofs).

The basic form of these arguments is something like this:

  1. If God exists, he must be like ‘X’.  [Here ‘X’ = some attribute(s) of God, e.g.,  he must be good, loving, omnipotent, etc.].
  2. ‘X’ is actually impossible.
  3. Therefore, God cannot exist.

Unlike the simplistic rants of some atheists online, these are sophisticated arguments that demand equally sophisticated responses. The argument forms are valid, so to prove them unsound, some premises must be shown to be false.

Another reason for my interest is that I found myself unhappy with the responses I saw from some Christian apologists. It seemed like they were allowing the atheists to set up the rules in such a way that they could not lose, and the apologists were playing into their hands. Further, it seemed that some of the solutions proposed by these apologists would lead to theological heresy.

I saw the overall problem as one of how God can be spoken of correctly without creating these dilemmas that atheists use to argue against his existence. I believe the answer can be found in the classical "doctrine of analogy" – a way of understanding God-talk that does not open itself up (as easily, at least) to ontological disproofs, and also safeguards orthodox theology.

That pretty much summarizes my dissertation. For those interested in the topic, a more robust discussion follows.

Constructing Ontological Disproofs

Constructing a basic ontological disproof is fairly straightforward:

  1. Assert that God must have some attribute (‘X’).
  2. Define ‘X’.
  3. Offer counterexample(s) to the possible actualization of ‘X’.
  4. Redefine ‘X’ to avoid counterexample(s) problem.
  5. Repeat 3 and 4 until procedure shows that ‘X’ cannot be actualized,.
  6. Conclude that because ‘X’ cannot be actualized, God cannot exist.


  • Omnipotence: The ability to do all things must include the ability to not do certain things, for some abilities preclude others by definition.
  • Omniscience: No other being can know propositions with certain indexicals (time, location, subject-object, etc).
  • Supernaturality: There must be at least one fundamental law of creation which is not a result of God’s will – that of God’s will being effective. Therefore God’s ability to will is also natural.

A variant of this kind of argument is to pit two attributes against one another. If it can be demonstrated that God must have two attributes that cannot actually coexist, then God cannot exist:

  1. Assert that God has attribute ‘X’.
  2. Assert that God has attribute ‘Y’.
  3. Show that A follows from ‘X’.
  4. Show that ~A follows from ‘Y’.
  5. Conclude that because “‘A’ and ‘~A'” cannot be true, God cannot exist.


  • Perfection vs. Creator: A perfect being needs nothing, but without a need God would not create.
  • Creator vs. Immutability: An unchanging being cannot intend to create at one time and not at another.
  • Immutability vs. Omniscience: An unchanging being cannot know changing truths (which differ from one time to another).
  • Transcendence vs. Omnipresence: A transcendent being cannot be present as well.
  • Justice vs. Mercy: No being can both give what one deserves and not give what one deserves.

Answering Ontological Disproofs

Modern Philosophy

Although many responses to these kinds of arguments have been offered, most follow the same basic method. Namely, they accept that the only way out of these logical conundrums is to change the definition of God’s attributes until they no longer suffer from the atheist’s attack, and proceed to do so until they have reached that goal. A good example of the procedure is found in two chapters of William Lane Craig and J. P. Moreland’s Philosophical Foundations for a Christian Worldview (reproduced online here). In his response to ontological disproofs, Craig makes two interesting remarks:

  1. Scripture gives philosophers a wide latitude with regard to doctrinal formulations.
  2. Anti-theistic critiques can be helpful in forming more adequate conceptions of doctrine.

He goes on to say that “two controls have tended to guide this inquiry into the divine nature: Scripture and Perfect Being theology.” He goes so far as to conclude that “Theists thus found that antitheistic critiques of certain conceptions of God could actually be quite helpful in framing a more adequate conception.” An example of this procedure is found in his response to problems of God’s immutability (changelessness):

"Rejection of radical immutability leaves it open for us to affirm nonetheless that God is immutable in the biblical sense of being constant and unchangeable in His character. Moreover, He is immutable in His existence (necessity, aseity, eternity) and His being omnipresent, omniscient, and omnipotent. These essential attributes are enough to safeguard God’s perfection without having Him frozen into immobility."

While “framing a more adequate conception” in this way might get around some skeptical arguments, this kind of thinking also leads Craig to deny that God is eternal (atemporal):

"A second powerful argument for divine temporality is based on God’s being all-knowing. In order to know the truth of propositions expressed by tensed sentences like “Christ is risen from the dead” God must exist temporally. For such knowledge locates the knower relative to the present."

Similar thinking has also led to Craig’s affirmation of admittedly heretical positions concerning God’s will and the the Son’s procession from the Father. By playing by the atheist’s rules, Craig and others may be handing over Christian orthodoxy in order to save (some kind of) theism.

I think the problem with most of these incoherency arguments, and many modern apologetic attempts to answer them by rethinking God’s attributes, is that they assume we can define God’s attributes in a univocal (same) manner according to how they are found in creatures. Definitions from finite reality are simply “blow them up” to the “size” of God (i.e., infinite).  For example, God’s omniscience (all-knowing) is defined as “knowing all true propositions” – as if making man’s limited knowledge of true propositions unlimited is all that is necessary to describe God’s knowledge. The problem is that such a method actually defines God’s attributes as “infinite finitude” or “limitless limits.” It is easy to see how contradictions will arise when an attribute of God is defined as an unlimited version of a necessarily limited concept. In theistic ontological disproofs, the atheist is simply noting this outcome.

Medieval Theology

Admittedly, in speaking about God, our language is using limited modes of expression. It must, for we have no other means of communication. All the words we have at our disposal are labels for things we experience in reality, and everything we experience is limited. It might seem, then, that univocal God-talk is all that is available to us if we are to say anything true about him. But because God transcends his limited creation, no concepts are attributable to God in the same way. On the other hand, we can say true things about God. So there must be a third way. That way is analogy.

In analogical talk, words mean similar things but are not univocal. We can speak of a  good knife and a good shoe, or say food is healthy and people are healthy. The common term in these pairs of statements have the same logical meaning, but do not pick out the same ontological reality. So while we can define “good” as “that which increases a thing’s ability to perform its function” we do not thereby say that “sharpness” in a good knife is the same as “comfort” in a shoe. Thus, in analogy we must know a thing’s nature – what it is, or what it is for – before we can know the meaning of the words used concerning it. For example, if I say, “My wife is a rose,” one immediately perceives that I am saying she is beautiful. Why not that she grows in the ground or photosynthesizes light? Because in knowing both the nature of a woman and the nature of a flower we can pick out logical similarities between them (e.g., beauty, softness, etc.) exclude dissimilarities (e.g., thorns, photosynthesis), then apply those logical similarities to the ontological realities.

With God we must continually purify our creaturely language of everything in it that is limited, image-bound, or imperfect. If we do not, we can easily be misled into thinking that the thoughts in our minds evoked by the terms we use in God-talk are really what they are in God. As Michael Martin himself notes:

“ordinary men tend to understand God in ways that are familiar to them despite the protests of theologians and intellectual ministers. As a result, God tends to be conceived of in the image of a man – a man much more powerful, moral, knowledgeable, and so on than ordinary men.”

Craig seems to agree with this assessment when he bemoans the problem of analogy:

"While we can say what God is not like, we cannot say what He is like, except in an  analogical sense–which must in the end fail, since there is no univocal element in the predicates we assign to God–, leaving us in a state of genuine agnosticism about the nature of God. Indeed, on this view God really has no nature; He is simply the inconceivable act of being. Why should we adopt so extraordinary a doctrine?"

I would say the reason we should accept such an “extraordinary doctrine” is that God is truly extra-ordinary! If God transcends all we know from finite reality, then we do not know his infinite nature directly. If we do not know God’s nature directly, then our words (which communicate only the finite reality in our minds) will fail to communicate the ontological essence of God – even when they are true statements. But we can know the truth of propositions about God without knowing God’s essence. For example we can know much about a person by looking at a painting of her, but paintings do not give us the true essence of a thing (one is paint on canvas, another is a human being). Another example: a child can know what it is to love pizza, love his toys, and love his parents – but when he considers that his parents love each other he does not really know what that love is. However, he can make true statements about their love and recognize their kind of love when he grows older and experiences it himself.

No creaturely words are used univocally (i.e., with the same meaning) of God and us; nor are they simply used equivocally (i.e., with two completely different meanings). Rather, God talk is analogical (i.e., in a way partly the same and partly different). So we must not confuse what we are thinking when we say something of God with what is literally true of him. Our talk of God is analogical – partly alike (univocal) and partly unlike (equivocal). We can thus speak truthfully of God in several ways:

  • Negation of the Limited (e.g., infinite, eternal, aseity, impassibility).
  • Super-Eminent Affirmation of the Unlimited (e.g., omnipotent, omnipresent, omniscient).*
  • Metaphor (e.g., God’s “arm,” God’s “repentance,” “fire,” “rock”).

To say this leads to “genuine agnosticism about the nature of God” or the view that “God really has no nature” is to confuse what we can know about God with knowing God. Knowing God is not simply affirming true propositions about him – it is having his very essence in our minds. As finite creatures, we cannot know infinite reality in this way. But we can know true statements about God. Univocity is not found in the ontological referents of words, but in their abstract definitions. Knowing that good is “comfortable” when said of a shoe (because a shoe’s purpose is comfort) and that good is “sharp” when said of a knife (because a knife’s purpose is to cut) does not help me know what good is in anything else unless I know what that thing is. But I can abstract from its usage that “good” means “attains to its purpose.” Thus I can affirm statements about another thing’s goodness when I know what it is. Since I do not fully know the ontological reality being picked out by the word when it is used of God, I may not know what it is (= have it existing in my mind) – but I can affirm that the statement “God is good” is true.


Good theology begins with proper metaphysics – not by simply denying finitude to finite concepts. This is why theological definitions based on classical metaphysics of God’s perfections often sound so obtuse:

Classical Understanding: Popular Understanding:
Omnipresent God is whole and entire in each and every place as an agent who is acting in all places. God is everywhere.
Immutable God has no passive potency. God cannot change.
Eternal God possesses perfect, all-at-once, unending life. God has no beginning or end.
Infinite God is an unreceived act of existing. God has no limits.
Omniscient There is nothing lacking in God’s knowledge of His being which, being the cause of all that comes to exist, gives God knowledge of all existing things. God knows everything.
Omnipotent God can actuate all potentials. God can do anything.


If the doctrine of analogy is correct, the linguistic precision with which these atheists (and their apologist correlatives) approach ontological disproof arguments is simply not available for use. Finite univocal concepts are necessarily incoherent when applied to an infinite being, and so their use will naturally result in contradictions. While perhaps too unwieldy for contemporary analytic philosophers, these more precise definitions do not open themselves to the same kinds of critiques when understood analogically.
(Image credit: Graphicality)

Douglas Beaumont

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Douglas Beaumont earned a Ph.D. in Theology at North-West University. He is the author of Evangelical Exodus, The Message Behind the Movie: How to Engage With a Film Without Disengaging Your Faith, and a contributor to The Best Catholic Writing. Follow Douglas at www.douglasbeaumont.com.

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