The Ontological Argument


The Ontological Argument is a highly sophisticated philosophical argument for the existence of God that is often poorly understood by believers and universally dismissed or even ridiculed by atheists, who usually do not properly grasp the argument either. In his anti-religious pamphlet "The God Delusion" Richard Dawkins made a complete fool of himself with the embarassing remark that the defendants of the Ontological Argument even "felt the need to resort to Modal Logic", which showed that he was completely ignorant of the fact that this argument simply is an exercise in modal logic (see this Q&A by William Lane Craig). The atheist philosopher Bertrand Russell once mocked the Ontological Argument as nothing but "a case of bad grammar". We will get back to him at the end of this post.


With this very first posting on my new blog, I want to provide an introduction to the famous Ontological Argument, and show how simple but ingenious and unrefuted it really is. When I first truly understood this argument for God's existence, I was absolutely thrilled by its force, and I hope you will be too, even though I have meanwhile become more skeptical of this argument because of my commitment to Thomist metaphysics.

If you do not like to read lengthy blog posts like this, you find an excellent introduction to the modern modal version of the Ontological Argument in these two short YouTube videos:

History of the argument:

The original version of the Ontological Argument was formulated in 1011 by the medieval philosopher and theologian Anselm of Canterbury, based on his "perfect being theology", which defines God as a maximally great being ("that which no greater can be conceived"). Anselm postulated "existence" as a great-making property, which led to the refutation of his argument by the famous German philosopher Kant, who recognized that "existence" is not a perfection and actually not even a characteristic that adds anything to the exhausting description of an object or being.


Alvin Plantinga (Wikimedia)
Alvin Plantinga (Wikimedia)

Surprisingly, the Ontological Argument was resurrected in the 20th century by the philosophers Charles Hartshorne and especially Alvin Plantinga from the University of Notre Dame, based on the possible world semantics of modal logic (= the philosophy or logic of the possible and the necessary). Hartshorne and Plantinga happily acknowledged that mere "existence" indeed is not a valid great-making property or perfection, but they discovered and established that "necessary existence" definitely is such a property.

Theoretical background:
Contingent existence means that a contingent being just happens to exist, but could well have not existed. Necessary existence instead means that a necessary being like God cannot fail to exist, or cannot not exist.
In the language of modal logic, things that are possible exist at least in one possible world, while things that are impossible exist in no possible world. Things that exist contingently exist only in some possible worlds, while things that exist necessarily exist in all possible worlds (please note that "possible worlds" are just "possible descriptions of reality" as philosophical tools and not equivalent to the parallel universes of modern physics).
This much theory is already sufficient to understand the Ontological Argument. So here we go:
The formal argument:
For the purpose of this essay, I reformulated the argument as follows:

Premise 1: A maximally great being must have the great making property of necessary existence.

Premise 2: If the existence of a being is necessary, it exists in all possible worlds.
Premise 3: If the existence of a being is possible, it exists in at least one possible world.
Premise 4: It is possible that a maximally great being, aka God, exists.
Conclusion: Consequently, God exists in one possible world, which implies that he exists in all possible worlds, including the actual world. Therefore, God exists!
A greatly simplified version of the argument makes it even more obvious:
Premise A: If a being that has the essential property to exist in all possible worlds does exists in one possible world, then it must exist by definition in all possible worlds.
Premise B: The existence of a maximally great being that necessarily exists in all possible worlds is possible, so that it exists in at least one possible world.
Conclusion: Therefore, such a being exists in all possible worlds including ours.
This argument is a deductive argument in the modus ponens and is universally accepted as logically valid (= properly formed according to the laws of logic). This means that the conclusions follow necessarily from the premises. Thus, our atheist friends cannot simply dismiss the argument because they do not like the conclusion. The only way to refute the argument is to show that one of the premises is false. Premise 1 has been established by Hartshorne and Plantinga as true. The truth of premises 3 and 4 (or of premise A in the simplified version) follows necessarily from modal logic and thus is undeniable.

Therefore, the only chance for the atheist is to deny premise 4 (premise B in the simplified version), which means that he has to deny that God (a maximally great being) is possible. The atheist has to claim that God is logically impossible, because the concept of a maximally great being is incoherent or self-contradictory, like a "round square" for example.

But the definition of a maximally great being (incl. the common omni-properties like omnipotence) does not include an explicit contradiction. Therefore, the only option would be a (non-obvious) implicit contradiction. No atheist and no philosopher ever suceeded in demonstrating such an implicit contradiction. Thus, we have no reason to assume that a maximally great being, even though it is well conceivable, is not possible.

Since the argument is logically valid and the premises are all rather true than false, the Ontological Argument is sound.


To avoid a common misunderstanding (e.g., by the skeptical philosopher David Hume; see here) it must be emphasized that the Ontological Argument does not try to prove the existence of God, but "only" shows that if his existence is possible than he must exist. Not too bad for a mere exercise in modal logic.

David Hume (Wikimedia)
David Hume (Wikimedia)

I already mentioned that Kant's objection against "existence" as perfection has been overcome by Hartshorne and Plantinga with the concept of "necessary existence" so that it does no longer apply  to modern modal versions of the Ontological Argument.
David Hume and Immanuel Kant furthermore denied that a logically or metaphysically necessary being is possible at all, because no being's non-existence implies a logical contradiction. They also claimed that the term "logically necessary being" entails a category mistake, as only the truth claims of propositions but not beings can possess the property of "logical necessity". Even some modern Christian philosophers agree, for example Richard Swinburne. This critique, if true, would be fatal for the Ontological Argument, because it depends on the concept of a logically necessary being. As explained by Moreland & Craig (2003) in Chapter 25 of "Philosophical Foundations for a Christian Worldview" this critique has been overturned by modern modal logic and its possible world sematics, which allow for a distinction between strict and broad logical necessity, of which Hume and Kant only refuted the former, while the Ontological Argument only depends on the latter unrefuted version. Furthermore, the mere fact that we can conceive the non-existence of God, does not mean that the non-existence of God is possible. There are potentially at lot of things we can conceive (e.g., finding a solution to the problem of squaring a circle), even though they are impossible.
The two main objections that have been broad forward against modern versions of the Ontological Argument are both based on parodies of the argument (Seigal 2008).

The earliest such objection was already made by the monk Gaunilo, a contemporary of Anselm. It represents a parody of the Ontological Argument, using an analogous argument to prove the existence of a "perfect island", as alleged reductio ad absurdum. Even though such parodies are still popular as objection among modern atheists, they are invalid arguments that involve incoherent concepts of "greatest beings", and completely ignore the crucial distinction between contingent and necessary beings, as well as the set of essential properties of a maximally great being (see here and here).

Michael Martin (1990) also formulated an objection in the form of a parody. He suggested that an analogous argument could be made for the existence of a maximally evil being. However, this argument must implicitly assume a particular ontology of values, in which Evil positively exists. Of course the majority of Christian philosophers would strongly reject such a assumption, and instead endorse the privation theory of evil, according to which any Evil is just an absence of Good. Under the classical privation theory of evil, Martin's evil God parody obviously cannot get off the ground (see here).

Many of the alleged "refutations" that you can find on YouTube or in the bestselling books of the New Atheists, are just nonsense arguments by village atheists and armchair philosophers that would never make it into a peer-reviewed journal for serious philosophy. The fact that such poor counter arguments have even been championed by distinguished scientists only shows that everything that scientists say outside their field of expertise should be taken with a grain of salt (of course this also applies to myself).

A perfect example is Douglas Gasking's absurd claim (quoted and supported by Richard Dawkins in "The God Delusion") that the Ontological Argument actually proves God's non-existence, because he would be a more formidable creator if he could create everything without even existing himself. It goes without saying that this is of course totally incoherent nonsense (see here).



Richard Dawkins (Wikimedia)
Richard Dawkins (Wikimedia)

A refutation of Dawkins' critique of the Ontological Argument by William Lane Craig, debating the empty chair of Richard Dawkins, who cowardly refuses any invitation to challenge him personally.

Likewise, naive attempts to "demonstrate" the alleged self-contradictory nature of great-making properties like omnipotence (e.g., "Can God create stone, which is so heavy that he cannot lift it?") fail miserably. No great-making property includes the capability to do the logically impossible. Even a maximally great and omnipotent God cannot create a married bachelor or make 2+2=5 true.



However, there is one remaining possibility, with which I actually sympathize, to get around the Ontological Argument. "Unfortunately" it is only open to the believer, but not to atheists:

One could deny the adequacy of modal logic by endorsing a metaphysical system, in which pure actuality (i.e. God not as a being among beings, also not as the greatest possible being, but as subsistent Being itself) is prior to any possibility, so that an attempt to prove the necessary existence of God with possible worlds semantics would be a futile endeavor that gets things totally backwards (see this blog post by Ed Feser). The only known philosophical system, which fulfills this criterion is Aristotelian metaphysics with its notions of act and potency, the 4 causes, prime matter and form (hylemorphism). Too bad for the atheist that this metaphysics also implies the necessary existence of an "unmoved mover" and first cause (God), which is why Thomas Aquinas adopted this metaphysics and made it to the official philosophy (Thomism) of the Catholic church.

Last but not least, I would like to briefly address two objections that have been raised against a necessarily existing creator in the context of Leibniz's Cosmological Argument, but which are also relevant here:

  1. Can a necessarily existing creator be the ultimate explanation for a contingent world?
  2. Wouldn't a necessarily existing, omnipotent, omniscient, and omnibenevolent Creator necessarily have to create the best of all possible worlds?

Based on his very strict version of the Principle of Sufficient Reason, Leibniz indeed believed that God had to create our world, which is the necessarily existing best of all possible worlds. This of course invited ridicule, because our world obviously is contingent and not the best possible world.


The first question raises the issue, if a necessary cause always implies a necessary effect. This would lead to Leibniz's necessitarianism, in which the existing world exists necessarily and could not have been otherwise. However, there is an obvious exception, which allows for a contingent effect to have a necessary cause: If the necessary cause would be a necessarily existing person, who is endowed with freedom of the will, which is what most theists believe anyway, than such a necessary being could be the creator of a contingent universe.


The second question is also easily answered, because even God cannot create a logically impossible world. However, a "best of all possible worlds" is logically impossible, because there simply is no best possible world. We can always imagine a world, which is better (e.g., in which one more person is saved). Therefore, God had only the choice to not create at all, or to create a contingent world like ours, which is very good, but not maximally good. There may be a reason, why Genesis 1 reports that "God saw all that He had made, and behold, it was very good" and did not say "... behold, it was perfect".


To sum up:

The Ontological Argument is either a valid and sound argument for the existence of God, or God exists necessarily as unmoved mover. All atheist critiques and alleged refutations do either not apply to the modern modal version of the argument, or are just "cases of bad grammar". Check mate Bertrand Russell, RIP!

Kommentar schreiben

Kommentare: 7
  • #1

    deadman932 (Montag, 14 Dezember 2015 18:23)

    Oh, please. you're another idiot looking for magic when time and natural processes will suffice -- largely because you're a fucking twat afraid of that stark reality

  • #2

    Günter Bechly (Montag, 14 Dezember 2015 19:17)

    I find it remarkable how atheists with a university degree (like Joe Padilla aka deadman932 ) disqualify themselves with such rude comments without any substance, and demonstrate with their behavior that they are unable to think rationally about the issue because they are obviously angry at God. I have seen such behavior often enough to recognize a pattern. Obviously, rational arguments hit a nerve in these people, who unintentionally confirm that fanatical fundamentalists abund in the irrational faith of atheism.

  • #3

    Mike Darwith (Sonntag, 22 Mai 2016 23:26)

    "...the mere fact that we can conceive the non-existence of God, does not mean that the non-existence of God is possible. There are potentially at lot of things we can conceive (e.g., a solution to the problem of squaring a circle), even though they are impossible." So, is it not then possible that even though we can conceive of the possible existence of God, it is possibly possible that God does not exist in any possible world, thus possibly undercutting premise 3? Premise 3 does not appear to be self-evident. Suppose we conceive that the non-existence of God is possible in some possible world, etc. At their core, aren't these ontological 'proofs' simply well disguised forms of a cunning tautology: God exists because it is impossible for him not to exist. I'm getting a "maximally great" headache from chasing this argument through all its permutations and disputations--and I thank you for your contribution.

  • #4

    Jack Frost (Dienstag, 24 Mai 2016 20:51)

    " And, of course, they do. Let's just run the argument in reverse.

    There is no entity which possesses maximal greatness.
    (Hence) There is no possible world in which there is an entity which possesses maximal greatness.

    Plainly enough, if you do not already accept the claim that there is an entity which possesses maximal greatness, then you won't agree that the first of these arguments is more acceptable than the second. So, as a proof of the existence of a being which posseses maximal greatness, Plantinga's argument seems to be a non-starter.

    Perhaps somewhat surprisingly, Plantinga himself agrees: the “victorious” modal ontological argument is not a proof of the existence of a being which possesses maximal greatness. But how, then, is it “victorious”? Plantinga writes: “Our verdict on these reformulated versions of St. Anselm's argument must be as follows. They cannot, perhaps, be said to prove or establish their conclusion. But since it is rational to accept their central premise, they do show that it is rational to accept that conclusion” (Plantinga 1974, 221).

    It is pretty clear that Plantinga's argument does not show what he claims that it shows. Consider, again, the argument: “Either God exists, or 2+2=5. It is not the case that 2+2=5. So God exists.” It is just a mistake for a theist to say: “Since the premise is true (and the argument is valid), this argument shows that the conclusion of the argument is true”. No-one thinks that that argument shows any such thing. Similarly, it is just a mistake for a theist to say: “Since it is rational to accept the premise (and the argument is valid), this argument shows that it is rational to accept the conclusion of the argument”. Again, no one thinks that that argument shows any such thing. But why don't these arguments show the things in question? There is room for argument about this. But it is at least plausible to claim that, in each case, any even minimally rational person who has doubts about the claimed status of the conclusion of the argument will have exactly the same doubts about the claimed status of the premise. If, for example, I doubt that it is rational to accept the claim that God exists, then you can be quite sure that I will doubt that it is rational to accept the claim that either 2+2=5 or God exists. But, of course, the very same point can be made about Plantinga's argument: anyone with even minimal rationality who understands the premise and the conclusion of the argument, and who has doubts about the claim that there is an entity which possesses maximal greatness, will have exactly the same doubts about the claim that there is a possible world in which there is an entity which possesses maximal greatness." -- Graham Oppy

  • #5

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  • #6

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  • #7

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